User:Marshallsumter/Radiation astronomy2/Submillimeters

Submillimetre astronomy or submillimeter astronomy is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre. Using submillimetre observations, astronomers examine molecular clouds and dark cloud cores with a goal of clarifying the process of star formation from earliest collapse to stellar birth.

Stellar astronomy
"This image [at right] shows two young brown dwarfs, objects that fall somewhere between planets and stars in terms of their temperature and mass. Brown dwarfs are cooler and less massive than stars, never igniting the nuclear fires that power their larger cousins, yet they are more massive (and normally warmer) than planets. When brown dwarfs are born, they heat the nearby gas and dust, which enables powerful infrared telescopes like NASA's Spitzer Space Telescope to detect their presence."

"Here we see a long sought-after view of these very young objects, labeled as A and B, which appear as closely-spaced purple-blue and orange-white dots at the very center of this image. The surrounding envelope of cool dust surrounding this nursery can be seen in purple."

"These twins, which were found in the region of the Taurus-Auriga star-formation complex, are the youngest of their kind ever detected. They are also helping astronomers solve a long-standing riddle about how brown dwarfs are formed more like stars or more like planets? Based on these findings, the researchers think they have found the answer: Brown dwarfs form like stars."

"This image combined data from three different telescopes on the ground and in space. Near-infrared observations collected at the Calar Alto Observatory in Spain cover wavelengths of 1.3 and 2.2 microns (rendered as blue). Spitzer's infrared array camera contributed the 4.5-micron (green) and 8.0-micron (yellow) observations, and its multiband imaging photometer added the 24-micron (red) component. The Caltech Submillimeter Observatory in Hawaii made the far-infrared observations at 350 microns (purple)."

Submillimeters
“[T]erahertz radiation refers to electromagnetic waves propagating at frequencies in the terahertz range. It is synonymously termed submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, THz. The term typically applies to electromagnetic radiation with frequencies between high-frequency edge of the microwave band, 300 gigahertz (3 x 1011 Hz)," and the long-wavelength edge of far-infrared light, 3000 GHz (3 x 1012 Hz or 3 THz). In wavelengths, this range corresponds to 0.1 mm (or 100 µm) infrared to 1.0 mm microwave.

Terahertz radiation is emitted as part of the black body radiation from anything with temperatures greater than about 10 kelvin. While this thermal emission is very weak, observations at these frequencies are important for characterizing the cold 10-20K dust in the interstellar medium in the Milky Way galaxy, and in distant starburst galaxies. Telescopes operating in this band include the James Clerk Maxwell Telescope, the Caltech Submillimeter Observatory and the Submillimeter Array at the Mauna Kea Observatory in Hawaii, the BLAST balloon borne telescope, the Herschel Space Observatory, and the Heinrich Hertz Submillimeter Telescope at the Mount Graham International Observatory in Arizona. The Atacama Large Millimeter Array, under construction, will operate in the submillimeter range. The opacity of the Earth's atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, or to space.

Planetary sciences
The underlying blue image shows an earlier picture obtained by the NASA/ESA Hubble Space Telescope. The new ALMA image has given astronomers a major breakthrough in understanding a nearby planetary system and provided valuable clues about how such systems form and evolve. Note that ALMA has so far only observed a part of the ring.

"Other important applications of gyrotrons are high-power microwave sources include high resolution radar ranging and imaging in atmospheric and planetary science as well as deep-space and specialized satellite communications and RF drivers for next-generation high-gradient linear accelerators".

Colors
NASA-led Study Sees Titan Glowing at Dusk and Dawn. Data map of gas clouds are over a linear sketch of the moon. High in the atmosphere of Titan, large patches of two trace gases glow near the north pole, on the dusk side of the moon, and near the south pole, on the dawn side. Brighter colors indicate stronger signals from the two gases, HNC (left) and HC3N (right); red hues indicate less pronounced signals.

New maps of Saturn’s moon Titan reveal large patches of trace gases shining brightly near the north and south poles. These regions are curiously shifted off the poles, to the east or west, so that dawn is breaking over the southern region while dusk is falling over the northern one.

The mapping comes from observations made by the Atacama Large Millimeter/submillimeter Array (ALMA), a network of high-precision antennas in Chile. At the wavelengths used by these antennas, the gas-rich areas in Titan’s atmosphere glowed brightly. And because of ALMA’s sensitivity, the researchers were able to obtain spatial maps of chemicals in Titan’s atmosphere from a “snapshot” observation that lasted less than three minutes.

At the highest altitudes, the gas pockets appeared to be shifted away from the poles. These off-pole locations are unexpected because the fast-moving winds in Titan’s middle atmosphere move in an east–west direction, forming zones similar to Jupiter’s bands, though much less pronounced. Within each zone, the atmospheric gases should, for the most part, be thoroughly mixed.

"A three-color (850, 650, and 350 GHz) single-pixel bolometer system has been installed [on the Atacama Submillimeter Telescope Experiment (ASTE)] and several massive star forming regions were mapped to derive submillimeter SEDs of these sources."

Minerals
This lovely rhodochrosite has excellent luster and a very juicy, cherry-red color. It is sparkly and bright, in part due to a druse on some crystal tips of submillimeter quartz, deposited atop. Many of the rhodochrosite scalenohedrons, which reach up to 1 cm in length, have this quartz cap which makes them look like white sugar was sprinkled atop. Some of the terminations are also sprinkled with glittering black, metallic crystals of manganite which increases the visual interest greatly. Overall, thus, we have the manganite and the quartz accents on an already superbly cherry-red rhodochrosite,

"Optical constants of natural minerals are of interest for characterizing interstellar dust, for remote sensing of terrain and for light scattering in the atmosphere by soil particles."

Theoretical submillimeter astronomy
Though there have been several other suspected, similarly booted black holes elsewhere, none has been confirmed so far. This object, detected by NASA's Hubble Space Telescope, is a very strong case. Weighing more than 1 billion suns, the rogue black hole is the most massive black hole ever detected to have been kicked out of its central home.

Estimate suggests that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. The most plausible explanation for this propulsive energy is that the monster object was given a kick by gravitational waves unleashed by the merger of two hefty black holes at the center of the host galaxy.

Hubble images taken in visible and near-infrared light provided the first clue that the galaxy was unusual. The images revealed a bright quasar, the energetic signature of a black hole, residing far from the galactic core. Black holes cannot be observed directly, but they are the energy source at the heart of quasars — intense, compact gushers of radiation that can outshine an entire galaxy. The quasar, named 3C 186, and its host galaxy reside 8 billion light-years away in a galaxy cluster.

"The submillimeter emission from [a cometary] nucleus can be estimated under the assumption of thermal equilibrium."

Entities
"By the words "warm cloud," we refer to the extended continuum emission -- characteristically several arcminutes in extent -- which can be detected as entities in the FIR and submillimeter regions of the spectrum."

"The Herschel Space Observatory has revealed [in the image at top right] how much dark matter it takes to form a new galaxy bursting with stars."

"If you start with too little dark matter, then a developing galaxy would peter out."

"If you have too much, then gas doesn't cool efficiently to form one large galaxy, and you end up with lots of smaller galaxies. But if you have the just the right amount of dark matter, then a galaxy bursting with stars will pop out."

"This remarkable discovery shows that early galaxies go through periods of star formation much more vigorous than in our present-day Milky Way."

"It showcases the importance of infrared astronomy, enabling us to peer behind veils of interstellar dust to see stars in their infancy."

"It turns out that it's much more effective to look at these patterns rather than the individual galaxies."

"This is like looking at a picture in a magazine from a reading distance. You don't notice the individual dots, but you see the big picture. Herschel gives us the big picture of these distant galaxies, showing the influence of dark matter."

"A region of the sky [at right] called the "Lockman Hole", located in the constellation of Ursa Major, is one of the areas surveyed in infrared light by the Herschel Space Observatory. All of the little dots in this picture are distant galaxies. The pattern of their collective light is what's known as the cosmic infrared background. By studying this pattern, astronomers were able to measure how much dark matter it takes to create a galaxy bursting with young stars."

Objects
The ALMA observations (orange and green, lower right) of the newborn star reveal a large energetic jet moving away from us, which in the visible is hidden by dust and gas. To the left (in pink and purple) the visible part of the jet is seen, streaming partly towards us.

"On the whole the emission strength is low in the submillimeter for astronomical objects."

Continua
ALMA has discovered and observed plenty of protoplanetary discs, but this disc is special as it shows two distinct spiral arms, almost like a tiny version of a spiral galaxy.

Previously, astronomers noted compelling spiral features on the surfaces of protoplanetary discs, but it was unknown if these same spiral patterns also emerged deep within the disc where planet formation takes place. ALMA, for the first time, was able to peer deep into the mid-plane of a disk and discovered the clear signature of spiral density waves.

Nearest to the star, ALMA found a flat disc of dust, which extends to what would approximately be the orbit of Neptune in our own Solar System. Beyond that point, in the region analogous to our Kuiper Belt, ALMA detected a narrow band with significantly less dust, which may be an indication for planet in formation. Springing from the outer edge of this gap are the two sweeping spiral arms that extend more than 10 billion kilometers away from their host star. The discovery of spiral waves at these extreme distances may have implications on the theory of planet formation.

Notation: let the symbol JCMT stand for the 15 m James Clerk Maxwell Telescope.

Notation: let the symbol IRAM stand for the 30 m Institute for Radio Astronomy in the Millimeter Range  telescope.

The "submillimeter continuum emission from the rich star-forming core, ρ Oph A, at 350, 450,800, and 1300 μm using the JCMT and IRAM 30 m telescopes [has been mapped]."

Emissions
Originally thought to be a nova, classifying this unusually shaped object correctly has proven challenging over the years. A number of possible explanations for its origins have been considered and discarded. It is now thought to be the result of two stars colliding — although there is still debate about what type of stars they were.

CK Vulpeculae was first spotted on 20 June 1670 by French monk and astronomer Père Dom Anthelme. When it first appeared it was easily visible with the naked eye; over the subsequent two years the flare varied in brightness and disappeared and reappeared twice, before finally vanishing from view for good.

During the twentieth century, astronomers came to understand that most novae could be explained by the runaway explosive behaviour and interactions between two close stars in a binary system. The features seen around CK Vulpeculae didn’t seem to fit this model particularly well,however, puzzling astronomers for many years.

The central part of the remnant has now been studied in detail using the Atacama Large Millimeter/submillimeter Array (ALMA). This striking image shows the best view of the object to date, and traces the cosmic dust and emission within and around CK Vulpeculae to reveal its intricate structure. CK Vulpeculae harbours a warped dusty disc at its centre and gaseous jets which indicate some central system propelling material outwards. These new observations are the first to bring this system into focus, suggesting a solution to a 348 year-old mystery.

"The spectrum includes dust continuum, molecular rotation line and atomic fine-structure line emissions."

"Stretching across almost 100 light-years of space, the Snake nebula is located about 11,700 light-years from Earth in the direction of the constellation Ophiuchus."

"In images from NASA's Spitzer Space Telescope, which observes infrared light, it appears as a sinuous, dark tendril against the starry background. It was targeted because it shows the potential to form many massive stars (stars with more than 8 times the mass of our Sun). SMA was used to observe sub-millimetre radiation from the nebula, radiation emitted between the infrared and radio parts of the electromagnetic spectrum."

"The two panels [at right] show the Snake nebula as photographed by the Spitzer and Herschel space telescopes. At mid-infrared wavelengths (the upper panel taken by Spitzer), the thick nebular material blocks light from more distant stars. At far-infrared wavelengths, however (the lower panel taken by Herschel), the nebula glows due to emission from cold dust. The two boxed regions, P1 and P6, were examined in more detail by the Submillimeter Array."

"To learn how stars form, we have to catch them in their earliest phases, while they're still deeply embedded in clouds of gas and dust, and the SMA is an excellent telescope to do so."

"The team studied two specific spots within the Snake nebula, designated P1 and P6. Within those two regions they detected a total of 23 cosmic "seeds" -- faintly glowing spots that will eventually give birth to between one and a few stars. The seeds generally weigh between 5 and 25 times the mass of the Sun, and each spans a few hundred billion kilometres (for comparison the average Earth-Sun distance is 150 million km). The sensitive, high-resolution SMA images not only unveil the small seeds, but also differentiate them in age."

"Previous theories proposed that high-mass stars form within very massive, isolated "cores" weighing at least 100 times the mass of the Sun. These new results show that that is not the case. The data also demonstrate that massive stars aren't born alone but in groups."

Absorptions
At right is a plot of the zenith atmospheric transmission on the summit of Mauna Kea throughout a range of 1 to 3 THz at a precipitable water vapor level of 0.001 mm. The graph was created using the CSO Atmospheric Transmission Interactive Plotter at the submillimeter wave astronomy site.

"O I, H2O and O2, and H2O and O2 ices have spectral signatures that lie at frequencies where the terrestrial atmospheric absorption prevents their study from ground-based telescopes, even at mountaintop sites."

The "Goddard High Resolution Spectrometer on board the Hubble Space Telescope, [... has been used to observe] interstellar O I λ1356 absorption toward 13 stars and infer that the total abundance of oxygen (gas plus grains) is homogeneous in the vicinity of the Sun and about two-thirds that of the solar value."

Bands
NGC 1087 (on the right) is a spiral galaxy located approximately 80 million light-years from Earth in the constellation of Cetus.

A "majority of [...] observations [may be] taken using a broadband filter of effective wavelength λ = 0.8 mm and fractional width Δλ/λ ~ 0.25 (Duncan et al. 1990)."

Backgrounds
All the objects that ALMA sees appear to be massive star-forming galaxies.

The background purple structure (on the left), as seen in visible light with the NASA/ESA Hubble Space Telescope, shows a classic double-lobe shape with a very narrow central region. ALMA’s ability to see the cold molecular gas reveals the nebula’s more elongated shape, in orange.

Since 2003 the nebula, located about 5000 light-years from Earth, has held the record for the coldest known object in the Universe. The nebula is thought to have formed from the envelope of a star in its later stages of life which engulfed a smaller, binary companion. It is possible that this is the cause of the ultra-cold outflows, which are illuminated by the light of the central, dying star.

ALMA looked at the nebula’s central dusty disc and the outflows further out, which span a distance of almost four light-years across the sky. These outflows are even colder than the cosmic microwave background, reaching temperatures below –270 °C. The outflows are also expanding at a speed of 590 000 kilometres per hour.

"The differential 850-μm counts are well described by the function


 * $$n(S) = N_0/(a + S^{3.2}),$$

where $$S$$ is the flux in mJy, $$N_0$$ = 3.0 × 104 per square degree per mJy, and $$a$$ = 0.4 − 1.0 is chosen to match the 850-μm extragalactic background light."

The "absorption and reradiation of light by dust in the history of galaxy formation and evolution is [...] the submillimeter extragalactic background light [(EBL). It] has approximately the same integrated energy density as the optical EBL."

Meteors
"[V]isible meteors consist of 0.1- to 1-mm-sized debris from active comets (Williams 1990)."

"This dramatic new image of cosmic clouds in the constellation of Orion reveals what seems to be a fiery ribbon in the sky. The orange glow represents faint light coming from grains of cold interstellar dust, at wavelengths too long for human eyes to see. It was observed by the ESO-operated Atacama Pathfinder Experiment (APEX) in Chile."

"In this image, the submillimetre-wavelength glow of the dust clouds is overlaid on a view of the region in the more familiar visible light, from the Digitized Sky Survey 2. The large bright cloud in the upper right of the image is the well-known Orion Nebula, also called Messier 42."

Cosmic rays
As a "cosmic-ray particle is absorbed [it causes] a rapid rise in temperature. Because it is not practical to prevent these events from occurring, it is necessary to understand their behavior so that they can be removed from raw data during analysis, in a process known as deglitching. This is particularly important when a bolometer is operated in a relatively high cosmic-ray flux such as is found on the Earth near the poles, or in space."

Neutrons
The millimeter light seen here pinpoints the location of the event to a distant host galaxy in images captured using the Hubble Space Telescope. The evolution of the millimeter light’s brightness provides information on the energy and geometry of the jets produced in the explosion.

"Due to nγ collisions of the ultrarelativistic neutrons with the submillimeter-IR photons, the neutrons with Lorentz factors Γ > Γesc [...] should degrade in the region r ≤ rmx responsible for the low-frequency radiation of [active galactic nuclei] AGN."

Protons
"Radio observations at 210 GHz taken by the Bernese Multibeam Radiometer for KOSMA (BEMRAK) [...] at submillimeter wavelengths [show an impulsive component that] starts simultaneously with high-energy (>200 MeV nucleon−1) proton acceleration and the production of pions. The derived radio source size is compact (≤10"), and the emission is cospatial with the location of precipitating flare-accelerated >30 MeV protons as seen in γ-ray imaging."

Electrons
The events surrounding the Big Bang were so cataclysmic that they left an indelible imprint on the fabric of the cosmos. We can detect these scars today by observing the oldest light in the Universe. As it was created nearly 14 billion years ago, this light — which exists now as weak microwave radiation and is thus named the cosmic microwave background (CMB) — has now expanded to permeate the entire cosmos, filling it with detectable photons. The CMB can be used to probe the cosmos via something known as the Sunyaev-Zel’dovich (SZ) effect, which was first observed over 30 years ago. We detect the CMB here on Earth when its constituent microwave photons travel to us through space. On their journey to us, they can pass through galaxy clusters that contain high-energy electrons. These electrons give the photons a tiny boost of energy. Detecting these boosted photons through our telescopes is challenging but important — they can help astronomers to understand some of the fundamental properties of the Universe, such as the location and distribution of dense galaxy clusters. This image shows the first measurements of the thermal Sunyaev-Zel’dovich effect from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile (in blue). Astronomers combined data from ALMA’s 7- and 12-metre antennas to produce the sharpest possible image. The target was one of the most massive known galaxy clusters, RX J1347.5–1145, the centre of which shows up here in the dark “hole” in the ALMA observations. The energy distribution of the CMB photons shifts and appears as a temperature decrease at the wavelength observed by ALMA, hence a dark patch is observed in this image at the location of the cluster.

"Radio observations at 210 GHz taken by the Bernese Multibeam Radiometer for KOSMA (BEMRAK) [of] high-energy particle acceleration during the energetic solar flare of 2003 October 28 [...] at submillimeter wavelengths [reveal] a gradual, long-lasting (>30 minutes) component with large apparent source sizes (~60"). Its spectrum below ~200 GHz is consistent with synchrotron emission from flare-accelerated electrons producing hard X-ray and γ-ray bremsstrahlung assuming a magnetic field strength of ≥200 G in the radio source and a confinement time of the radio-emitting electrons in the source of less than 30 s. [... There is a] close correlation in time and space of radio emission with the production of pions".

Gamma rays
Notation: let the symbol SCUBA represent Submillimetre Common-User Bolometer Array.

Observations of gamma-ray bursts have been made using the SCUBA instrument on the James Clerk Maxwell Telescope.

A "fading counterpart to GRB 980329 at 850 μm [has been found]. [...] the sub-millimeter flux was relatively bright. [...] The radio through sub-millimeter spectrum of GRB 980329 is well fit by a power law with index α = +0.9. However, we cannot exclude a ν1/3 power law attenuated by synchrotron self-absorption."

"The sub-millimeter [...] is where the emission peaks in some bursts [occur] in the days to weeks following the burst. The sub-millimeter emission is not affected by extinction local to the source or interstellar scintillation."

Submillimeter observations
 * 1) determine "the breaks in the radio to sub-millimeter to optical spectrum so that the spectral shape can be compared to the synchrotron models"
 * 2) determine "the evolution of the sub-millimeter flux" and
 * 3) look "for underlying quiescent sources that may be dusty star-forming galaxies at high redshifts."

X-rays
"The BeppoSAX GRB Monitor was triggered on 1998 March 29.156 UT (Frontera et al. 1998a) [GRB 980329]. This was the brightest burst that had been seen simultaneously by the BeppoSAX Wide Field Camera, with a peak flux ~ 6 Crab in the 2-26 keV band. A fading X-ray source 1SAX J0702.6+3850 was found using the BeppoSAX Narrow Field Instruments (in't Zand et al. 1998)."

At right is "[c]olour composite image of Centaurus A [NGC 5128], revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the stars and the galaxy’s characteristic dust lane in close to "true colour"."

The optical blue band is centered at 445 nm, the optical green band is centered at 551 nm, and the optical red is centered at 658 nm. The submillimeter band (Atacama Pathfinder Experiment) in yellow is centered at 870 µm.

Opticals
The Atacama Large Millimeter/submillimeter Array (ALMA) imaged this disc in high resolution by picking up faint signals from its constituent millimetre-sized dust grains. The vivid rings are thick bands of dust, separated by deep gaps.

Optimised to study the cold gas and dust of systems like HD 169142, ALMA’s sharp eyes have revealed the structure of many infant solar systems with similar cavities and gaps. A variety of theories have been proposed to explain them — such as turbulence caused by magnetorotational instability, or the fusing of dust grains — but the most plausible explanation is that these pronounced gaps were carved out by giant protoplanets.

When solar systems form gas and dust coalesce into planets. These planets then effectively spring clean their orbits, clearing them of gas and dust and herding the remaining material into well-defined bands. The deep gaps seen in this image are consistent with the presence of multiple protoplanets — a finding that agrees with other optical and infrared studies of the same system. Observing such dusty protoplanetary discs with ALMA allows scientists to investigate the first steps of planet formation in a bid to unveil the evolutionary paths of these infant systems.

The "effective opacity decreases as a+ [the maximum grain radius] increases in [the] radius range [1 to 100 mm], apparently because the larger particles become individually optically thick and so contribute to the mass [the total grain mass of the cometary coma] faster than they contribute to the radiating cross section."

Visuals
"This image composite shows a warped and magnified view of a galaxy discovered by the Herschel Space Observatory, one of five such galaxies uncovered by the infrared telescope. The galaxy -- referred to as "SDP 81" -- is the yellow dot in the left image taken by Herschel. It can also be seen as the pink smudges in the right image, a composite of ground-based observations showing more detail."

"Herschel was able to find the galaxy, which is buried in dust, because it happens to be positioned behind another galaxy (blue blob at right), which is acting like a cosmic lens to make it appear brighter. The gravity of the foreground galaxy is distorting and magnifying the distant galaxy's light, causing it to appear in multiple places, as seen as the pink smudges. The distant galaxy is so far away that its light took about 11 billion years to reach us."

"Herschel couldn't detect the foreground galaxy, but astronomers were able to spot it in visible light using the W.M. Keck Observatory. Several follow-up observations by ground telescopes helped to get a better view of the distant galaxy. For example, the pink smudges at the right show wavelengths that are even longer than what Herschel sees in the submillimeter portion of the electromagnetic spectrum. Those observations were made by the Smithsonian Astrophysical Observatory's Submillimeter Array in Hawaii."

Greens
"The Boomerang Nebula is a young planetary nebula and the coldest object found in the Universe so far. The NASA/ESA Hubble Space Telescope image is yet another example of how Hubble's sharp eye reveals surprising details in celestial objects."

"NASA's Hubble Space Telescope caught the Boomerang Nebula [at second right] in images taken with the Advanced Camera for Surveys in early 2005. This reflecting cloud of dust and gas has two nearly symmetric lobes of matter that are being ejected from a central star. Each lobe of the nebula is nearly one light-year in length, making the total length of the nebula half as long as the distance from our Sun to our nearest neighbors- the Alpha Centauri stellar system, located roughly 4 light-years away. The Boomerang Nebula resides 5,000 light-years from Earth. Hubble's sharp view is able to resolve patterns and ripples in the nebula very close to the central star that are not visible from the ground."

"This NASA/ESA Hubble Space Telescope image [at top right] shows a young planetary nebula known (rather curiously) as the Boomerang Nebula. It is in the constellation of Centaurus, 5000 light-years from Earth. Planetary nebulae form around a bright, central star when it expels gas in the last stages of its life."

"The Boomerang Nebula is one of the Universe's peculiar places. In 1995, using the 15-metre Swedish ESO Submillimetre Telescope in Chile, astronomers Sahai and Nyman revealed that it is the coldest place in the Universe found so far. With a temperature of -272C, it is only 1 degree warmer than absolute zero (the lowest limit for all temperatures). Even the -270C background glow from the Big Bang is warmer than this nebula. It is the only object found so far that has a temperature lower than the background radiation."

"The Hubble telescope took this image in 1998. It shows faint arcs and ghostly filaments embedded within the diffuse gas of the nebula's smooth 'bow tie' lobes. The diffuse bow-tie shape of this nebula makes it quite different from other observed planetary nebulae, which normally have lobes that look more like 'bubbles' blown in the gas. However, the Boomerang Nebula is so young that it may not have had time to develop these structures. Why planetary nebulae have so many different shapes is still a mystery."

"The general bow-tie shape of the Boomerang appears to have been created by a very fierce 500 000 kilometre-per-hour wind blowing ultracold gas away from the dying central star. The star has been losing as much as one-thousandth of a solar mass of material per year for 1500 years. This is 10-100 times more than in other similar objects. The rapid expansion of the nebula has enabled it to become the coldest known region in the Universe."

"The image was exposed for 1000 seconds through a green-yellow filter. The light in the image comes from starlight from the central star reflected by dust particles." The image pixels have been coded blue even though the filter is centered at 606 nm.

"The Boomerang nebula, called the "coldest place in the universe," reveals its true shape to the Atacama Large Millimeter/submillimeter Array (ALMA) telescope. The background blue structure, as seen in visible light by NASA's Hubble Space Telescope, shows a classic double-lobe shape with a very narrow central region. ALMA’s resolution and ability to see the cold gas molecules reveals the nebula’s more elongated shape, as seen in red."

Infrareds
"It was not until after the variable radio source was discovered that infrared observations [of GRB 980329] found a fading counterpart (Klose et al. 1998; Palazzi et al. 1998; Metzger 1998): this indicated that the optical extinction was significant for this source (Larkin et al. 1998; Taylor et al. 1998b), and/or the redshift was large (Fruchter 1999)."

"Starting on 1998 April 5, we made a series of photometry observations of VLA J070238.0+385044 using SCUBA. [...] On April 5.2 UT, we detected the source at 850 μm with a flux density of 5 ± 1.5 mJy. This source was confirmed on April 6.2 with a flux density of 4 ± 1.2 mJy, resulting in an average of 4.5 ± 1 mJy over the two days."

"The NASA Spitzer Space Telescope has obtained the first infrared images of the dust disc surrounding Fomalhaut, the 18th brightest star in the sky. Planets are believed to form from such a flattened disc-like cloud of gas and dust orbiting a star very early in its life. The Spitzer telescope was designed in part to study these circumstellar discs, where the dust particles are so cold that they radiate primarily at infrared wavelengths. Located in the constellation Piscis Austrinus, the parent star and its putative planetary system are found at a distance of 25 light-years."

"Twenty years ago, the Infrared Astronomical Satellite, the first orbiting infrared telescope, detected much more infrared radiation coming from Fomalhaut than was expected for a normal star of this type. The dust is presumed to be debris left over from the formation of a planetary system. However, the satellite did not have adequate spatial resolution to image the dust directly. Subsequent measurements with sub-millimeter radio telescopes suggested that Fomalhaut is surrounded by a huge dust ring 370 astronomical units (an astronomical unit is the average distance between the Sun and Earth), or 34 billion miles (56 billion kilometers) in diameter. This corresponds to a size of nearly five times larger than our own solar system. Moreover, the sub-millimeter observations (far right image) revealed that the ring was inclined 20 degrees from an edge-on view."

"The new images obtained with the multiband imaging photometer onboard Spitzer confirm this general picture, while revealing important new details of Fomalhaut's circumstellar dust. The 70-micron data (red) clearly shows an asymmetry in the dust distribution, with the southern lobe one-third brighter than the northern. Such an unbalanced structure could be produced by a collision between moderate-sized asteroids in the recent past (releasing a localized cloud of dust) or by the steering effects of ring particles by the gravitational influence of an unseen planet."

"At 24 microns (green), the Spitzer image shows that the center of the ring is not empty. [Note that an image of a reference star was subtracted from the Fomalhaut image to reveal the faint disc emission.] Instead, the 'doughnut hole' is filled with warmer dust that extends inward to within at least 10 astronomical units of the parent star. This warm inner disc of dust occupies the region that is most likely to be occupied by planets and may be analogous to our solar system's 'zodiacal cloud' -- but with considerably more dust. One possible explanation for this warmer dust is that comets are being nudged out of the circumstellar ring by the gravitational influence of massive planets. These comets then loop in toward the central star, releasing dust particles just as comets do in our own solar system."

Radios
The image on the right is the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape. Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a shadow) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations. In additionto other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, co-owned and co-operated by ESO is a partner on behalf of its member states in Europe.

"Inside [the] X-ray error box [for GRB 980329], a variable radio source VLA J070238.0+385044 was found that was similar to GRB 970508 (Taylor et al. 1998a, 1998b)."

Plasma objects
This image on the right, captured for the very first time at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA), is special because it shows the jets emitted by a hot, swirling disc of material encircling the black hole at SS 433’s centre. Owing to its relative proximity, SS 433 is a particularly useful object for researchers looking to learn more about microquasars and the jets they emit.

The corkscrew shape visible here is created by a phenomenon known as precession; as they move outwards through space, these two jets are slowly tumbling around an axis in a similar way to the motion of a gyroscope or a spinning top slowing down, the orientation of their rotational axes changing as they do so. The scale of this corkscrew is enormous, at 5000 times the size of the Solar System.

One remarkable aspect of this observation is that its detailed shape was entirely predicted from spectroscopic measurements by the Global Jet Watch telescopes in the preceding year before the ALMA observations were made. The sequence of these observations allowed researchers to make and test predictions about the paths the jets would take, representing a new milestone in the study of microquasars. The observations have also resolved the question of why the jets are still hot at such great distances from their origin — ALMA’s sensitivity enabled researchers to identify that reheating of the plasma occurs when successive jet surges expand and collide with one another.

Gaseous objects
"This image [at right] from the Herschel Observatory reveals some of the coldest and darkest material in our galaxy. The choppy clouds of gas and dust pictured here are just starting to condense into new stars. The yellow filaments show the coldest dust dotted with the youngest embryonic stars."

"Infrared, or submillimeter, light with a wavelength of 250 microns is represented in blue; 350-micron light in green; and 500-micron light in red. Much of this region of our galaxy would be hidden in visible-light views."

"The area pictured is in the plane of our Milky Way galaxy, 60 degrees from the center. It spans a region 2.1 by 2.1 degrees. This image was taken by Herschel's spectral and photometric imaging receiver."

Liquid objects
"This is one of the early spectra obtained with the SPIRE fourier transform spectrometer on Herschel. Shown here is a portion of the SPIRE spectrum of VY Canis Majoris (VY CMa), a red supergiant star near the end of its life, which is ejecting huge quantities of gas and dust into interstellar space. The inset is a SPIRE camera map of VY CMa, in which it appears as a bright compact source near the edge of a large extended cloud."

"The VY CMa spectrum is amazingly rich, with prominent features from carbon monoxide (CO) and water (H2O). More than 200 other spectral features have been identified so far in the full spectrum, and several unidentified features are being investigated. Many of the features are due to water, showing that the star is surrounded by large quantities of hot steam. Observations like these will help to establish a detailed picture of the mass loss from stars and the complex chemistry occurring in their extended envelopes. As in all of the SPIRE spectra, the underlying emission increases towards shorter wavelengths, and is due to the emission from dust grains. The shape of the dust spectrum provides information on the properties of the dust."

"VY Canis Majoris (VY CMa) is a red supergiant star located about 4900 light years from Earth in the constellation Canis Major. It is the largest known star, with a size of 2600 solar radii, and also one of the most luminous, with a luminosity in excess of 100 000 times that of the Sun. The mass of VY CMa lies in the range 30-40 solar masses, and it has a mass-loss rate of 2 x 10-4 solar masses per year."

"The shell of gas it has ejected displays a complex structure; the circumstellar envelope is among the most remarkable chemical laboratories known in the Universe, creating a rich set of organic and inorganic molecules and dust species. Through stellar winds, these inorganic and organic compounds are injected into the interstellar medium, from which new stars orbited by new planets may form. Most of the carbon supporting life on Earth was forged by this kind of evolved star. VY CMa truly is a spectacular object, it is close to the end of its life and could explode as a supernova at any time."

Rocky objects
"On 24 June 2009, SPIRE recorded its first images during the in-orbit commissioning phase of the Herschel mission. This picture, made before fine-tuning or in-orbit final calibration was performed, shows a SPIRE image of the galaxy M74 at a wavelength of 250 microns. The image traces emission by dust in clouds where star formation are active, and the nucleus and spiral arms show up clearly. Dust is part of the interstellar material fuelling star formation, and this image effectively shows the reservoirs of gas and dust that are available to be turned into stars in the galaxy. Significantly, the image frame is also filled with many other galaxies which are much more distant and only show up as point sources. There are also some extended structures, possibly due to clouds of dust in our own galaxy."

"M74 (also known as NGC 628) is a face-on spiral galaxy located about 24 million light-years from Earth in the constellation Pisces. Visible light, produced mainly by the stars within the galaxy, reveals a bright nucleus and well-defined spiral arms that contain many small, bright regions where young massive stars have formed recently. The submillimetre SPIRE image traces the cold dust between the stars, and the spiral arms appear much more enhanced. This galaxy also contains many faint dots that are actually distant galaxies in the background and dust radiating at submillimetre wavelengths but are too distant for the structure in the galaxies to be resolved."

Ions
The image at right is a colour "composite image of RCW120. It reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps where new stars are then formed. The 870-micron submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope. Here, the submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas (shown with data from the SuperCosmos H-alpha survey). The image also contains data from the Second Generation Digitized Sky Survey (I-band shown in blue, R-band shown in red)."

Compounds
"The HIFI spectrum of the Orion Nebula, superimposed on a Spitzer image of Orion. A characteristic feature is the spectral richness: among the organic molecules identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulfur oxide, sulfur dioxide and their isotope analogues. It is expected that new molecules will also be identified. This spectrum is the first glimpse at the spectral richness of regions of star and planet formation. It harbors the promise of a deep understanding of the chemistry of space once the complete spectral surveys are available."

"This HIFI spectrum was obtained for the Herschel HEXOS Key Program - a scientific investigation using the Herschel HIFI and PACS instruments to perform full line surveys of five sources in the Orion and Sagittarius B2 molecular clouds."

Hydrogen fluoride
"[T]he detection of absorption by interstellar hydrogen fluoride (HF) [in the submillimeter band occurs] along the sight line to the submillimeter continuum sources W49N and W51."

"[T]he 1232.4762 GHz J = 1-0 HF transition [has been observed] in the upper sideband of the band 5a receiver."

"HF is the dominant reservoir of fluorine wherever the interstellar H2/atomic H ratio exceeds ~ 1; the unusual behavior of fluorine is explained by its unique thermochemistry, F being the only atom in the periodic table that can react exothermically with H2 to form a hydride."

The observations "toward W49N and W51 [occurred] on 2010 March 22 ... The observations were carried out at three different local oscillator (LO) tunings in order to securely identify the HF line toward both sight lines. The dual beam switch mode (DBS) was used with a reference position located 3' on either side of the source position along an East-West axis. We centered the telescope beam at α =19h10m13.2s, δ = 09°06'12.0" for W49N and α = 19h23m43.9s, δ = 14°30'30.5" for W51 (J2000.0). The total on-source integration time amounts to 222s on each source using the Wide Band Spectrometer (WBS) that offers a spectral resolution of 1.1 MHz (~0.3 km s-1 at 1232 GHz)."

Hydrogen chloride
"[T]he first detection of chloronium, H2Cl+, in the interstellar medium, [occurred on March 1 and March 23, 2010,] using the HIFI instrument aboard the Herschel Space Observatory. The 212 − 101 lines of ortho-H235Cl+ and ortho-H237Cl+ are detected in absorption towards NGC 6334I, and the 111 − 000 transition of para-H235Cl+ is detected in absorption towards NGC 6334I and Sgr B2(S)."

Carbon monoxide
"The Antennae Galaxies (also known as NGC 4038 and 4039) are a pair of distorted colliding spiral galaxies about 70 million light-years away, in the constellation of Corvus (The Crow). This view combines ALMA observations, made in two different wavelength ranges during the observatory’s early testing phase, with visible-light observations from the NASA/ESA Hubble Space Telescope."

"The Hubble image is the sharpest view of this object ever taken and serves as the ultimate benchmark in terms of resolution. ALMA observes at much longer wavelengths which makes it much harder to obtain comparably sharp images. However, when the full ALMA array is completed its vision will be up to ten times sharper than Hubble."

"Most of the ALMA test observations used to create this image were made using only twelve antennas working together — far fewer than will be used for the first science observations — and much closer together as well. Both of these factors make the new image just a taster of what is to come. As the observatory grows, the sharpness, speed, and quality of its observations will increase dramatically as more antennas become available and the array grows in size. This is nevertheless the best submillimetre-wavelength image ever taken of the Antennae Galaxies and opens a new window on the submillimetre Universe."

"While visible light — shown here mainly in blue — reveals the newborn stars in the galaxies, ALMA’s view shows us something that cannot be seen at those wavelengths: the clouds of dense cold gas from which new stars form. The ALMA observations — shown here in red, pink and yellow — were made at specific wavelengths of millimetre and submillimetre light (ALMA bands 3 and 7), tuned to detect carbon monoxide molecules in the otherwise invisible hydrogen clouds, where new stars are forming."

"Massive concentrations of gas are found not only in the hearts of the two galaxies but also in the chaotic region where they are colliding. Here, the total amount of gas is billions of times the mass of the Sun — a rich reservoir of material for future generations of stars."

On the left is a 3 dimensional map of carbon monoxide (CO) in the Helix Nebula. The third dimension is provided by the radial velocity of the carbon monoxide. Since the neutral envelope (which contains the CO) is expanding away from the central star, the radial velocity of a spectral component approximates the spacial position in the radial (away from Earth) dimension, which allows a 3D map to be produced. Light features in each view are close to the observer, darker ones are further away. This map was made from observations of the CO(2-1) rotational line at 230 GHz, using the Caltech Submillimeter Observatory, during 1993 and 1994.

Atmospheres
The image of the left shows a wide-field view of the region, as seen with the HAWK-I instrument, installed at the Very Large Telescope. A small region is highlighted with a white rectangle, and the rightmost image shows that region in stunning fiery detail, observed with the Atacama Large Millimeter/submillimeter Array (ALMA).

As well as producing beautiful images, molecular clouds are of great interest to astronomers. The clouds are stellar nurseries and at their edge atoms react and form molecules by key astrochemical processes. With the ALMA observations scientists were able to resolve this transition from atomic to molecular gas at the border of the Orion molecular cloud. As Orion is the nearest massive star-forming region it is the ideal target to find out more about these astrochemical processes, and it also offers the possibility to study the interactions of newly formed stars with their surroundings in detail.

Both observations show that this fascinating astrochemical transition from atomic to molecular gas happens in a highly dynamic environment. ALMA’s view of the nebula particularly resembles the dark clouds of a huge upcoming storm in Earth’s atmosphere.

Materials
"Calculations were made using the wavelength-dependent complex refractive indices of silicate (Draine 1985), glassy carbon (Edoh 1983), and Tholin (Khare et al. 1984). [...] these materials were chosen as broadly representative of the types of matter thought to be present in comet dust."

"Observations using the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed an unexpected spiral structure in the material around the old star R Sculptoris. This feature has never been seen before and is probably caused by a hidden companion star orbiting the star. This slice through the new ALMA data reveals the shell around the star, which shows up as the outer circular ring, as well as a very clear spiral structure in the inner material." The image band is centered at 870 µm.

Shelters
The image at right shows the protective dome or shelter for the Caltech Submillimeter Observatory at the Mauna Kea Observatory.

Coronal clouds
An "intense solar flare spectral radiation component, peaking somewhere in the shorter submillimeter to far-infrared range, [is] identified during the 2003 November 4 large flare. The new solar submillimeter telescope, designed to extend the frequency range to above 100 GHz, detected this new component with increasing fluxes between 212 and 405 GHz."

Moon
"This is the Moon seen with SCUBA-2, at wavelengths of 0.45 mm (top left) and 0.85 mm (top right). The bottom left shows a combination of the SCUBA-2 images which give the temperature of the lunar surface, where red is warmest. At the lower right is a visible light image taken at the same time."

"While the optical image shows sunlight reflected from the surface of the Moon, the submillimetre emission detected by SCUBA-2 is being radiated from the Moon itself. The SCUBA-2 temperature map shows that the unilluminated side of the Moon is colder (green and blue), with the coldest region (blue) being where the Sun last heated the surface. The Moon was in "waxing gibbous" phase, meaning that it is on its way to becoming full."

Mars
"[A]bsorption features in the submillimeter spectrum of Mars ... are due to the H2O (110-101) and 13CO (5-4) rotational transitions."

"The distribution of water in the Martian atmosphere matches a profile of constant, 100% saturation from 10 to 45 km altitude."

"The primary pointing and calibration source was Mars [observations on November 18-20 and 22-24, 1989 UTC], for which we adopted the 0.8-mm flux density S0.8 = 222 Jy (brightness temperature TB = 210 K) on each night."

"Observations were obtained UT 1990 April 25 and 26 at 800 μm. The primary pointing and flux calibration sources were Mars (S0.8 = 619 Jy; TB = 222 K) and Uranus (S0.8 = 85 Jy; TB = 84 K)".

"Observations were obtained UT 1990 August 2 and 3. The primary pointing and calibration source was Mars, for which S0.8 = 1311 Jy (TB = 221 K) and S1.1 = 697 Jy (TB = 220 K)."

Jupiter
"[F]or wavelengths between 0.35 and 0.45 mm ... the radiances can be matched by models which include NH3 ice particles which are between 30 and 100 µm in size, regardless of the scale height characterizing the cloud."

The map at right "shows the distribution of water in the stratosphere of Jupiter as measured with the Herschel space observatory. White and cyan indicate highest concentration of water, and blue indicates lesser amounts. The map has been superimposed over an image of Jupiter taken at visible wavelengths with the NASA/ESA Hubble Space Telescope."

"The distribution of water clearly shows an asymmetric distribution across the planet: water is more abundant in the southern hemisphere. Based on this and other clues collected with Herschel, astronomers have established that at least 95 percent of the water currently present in Jupiter's stratosphere was supplied by comet Shoemaker-Levy 9, which famously impacted the planet at intermediate southern latitudes in 1994."

"The map is based on spectrometric data collected with the Photodetecting Array Camera and Spectrometer (PACS) instrument on board Herschel around 66.4 microns, a wavelength that corresponds to one of water's many spectral signatures."

"Jupiter and the Galilean moons [are] seen with SCUBA-2 [in the image at the top of this section]. Rather than seeing the sunlight reflected off the surface of these moons, such as Galileo did 400 years ago, this SCUBA-2 image shows the energy being radiated from the moons themselves."

The order of submillimeter intensity appears to be Ganymede, Callisto, Io, and Europa.

Comets
"Comet [Okazaki-Levy-Rudenko] was [observed November 18-20 and 22-24, 1989 UTC and] found to be a weak but persistent source at 800 μm".

This close pass of comet 46P/Wirtanen gave astronomers the chance to observe the comet in detail, and ALMA (the Atacama Large Millimeter/submillimeter Array) took full advantage. ALMA’s speciality is observing the cooler components of the Universe, such as gas and dust, and the array often focuses on specific molecules. This image is no exception, as it highlights one key thing: the hydrogen cyanide gas in the coma around the comet’s nucleus.

But why would scientists be looking for an infamous poison? Well, it turns out that hydrogen cyanide is as common as mystery novels have led us to believe — throughout the cosmos, at least! Because it’s a simple organic molecule that forms relatively easily, it’s been observed in comets, stellar atmospheres, and the clouds of dust and gas that exist between stars. This image builds on those observations by showing clearly the hydrogen cyanide emanating from the nucleus of this comet. Further ALMA observations showed that other, more complex organic molecules were present, too.

This matters because, while it may be poisonous to many organisms on Earth today, hydrogen cyanide may have played an important role in getting life started on Earth. It’s very reactive, so it easily interacts with surrounding chemicals to create new molecules — including some of those essential for life, such as amino acids. One theory posits that hydrogen cyanide, brought here in part by comets, jump-started organic chemistry here on Earth, eventually leading to the beginning of life. ALMA’s imaging of 46P/Wirtanen further supports the idea that comets could have brought this life-giving material to the early Earth.

Saturn
"[T]he PH3 1-0 rotational line (266.9 GHz) line [has been detected] in [the atmosphere of] Saturn".

Uranus
For observations on "UT 1991 November 19 and 20[, the] primary pointing and calibration source was Uranus, for which we used S0.8 = 73.5 Jy (TB = 84 K) and S1.1 = 43.4 Jy (TB = 93 K)."

"As a demonstration of ALMA's new short wavelength capabilities, the commissioning team released a new image of planet Uranus as it appears in submillimetre wavelength light. The image — obtained with ALMA's shortest wavelength, Band 10 receivers — reveals the icy glow from the planet's atmosphere, which can reach temperatures as low as -224 C (giving Uranus the coldest atmosphere in the Solar System). ALMA's now broader range of capabilities will enable astronomers and planetary scientists to study and monitor temperature changes at different altitudes above the clouds of Uranus and other giant planets in our Solar System."

Neptune
"Neptune was also observed [on UT 1991 November 19 and 20], with adopted flux densities S0.8 = 27.5 Jy (TB = 79 K) and S1.1 = 16.6 Jy (TB = 88 K)."

Pluto
Precision measurements of Pluto's location and orbit around the Sun helps NASA’s New Horizons spacecraft accurately home in on its target when it nears Pluto and its five known moons in July 2015. This picture shows the cold surface of Pluto and its largest moon Charon as seen with ALMA on 15 July 2014.

Interstellar medium
The submillimeter "wavelength view [at right] of a ring of dust particles around Epsilon Eridani, taken with the SCUBA camera at the James Clerk Maxwell Telescope. The false-colour scale is brightest where there is more dust. Epsilon Eridani is marked by the star symbol, although the star itself is not seen at submillimetre wavelengths. Pluto's orbit (marking the edge of our Solar System) is shown at the same scale."

"The ring is "strikingly similar" to the outer comet zone in our Solar System, and shows an intriguing bright region that may be particles trapped around a young planet."

"What we see looks just like the comet belt on the outskirts of our Solar System, only younger, [...] It's the first time we've seen anything like this around a star similar to our Sun. In addition, we were amazed to see a bright spot in the ring, which may be dust trapped in orbit around a planet."

"Epsilon Eridani is far more similar to our Sun than either Vega or Fomalhaut."

"This star system is a strong candidate for planets, but if there are planets, it's unlikely there could be life yet. When the Earth was this young, it was still being very heavily bombarded by comets and other debris."

"It is also a star in our local neighbourhood, being only about 10 light years away, which is why we can see so much detail in the new image."

"If an astronomer could have seen what our Solar System looked like four billion years ago, it would have been very much as Epsilon Eridani looks today, [...] This is a star system very like our own, and the first time anyone has found something that truly resembles our Solar System; it's one thing to suspect that it exists, but another to actually see it, and this is the first observational evidence."

"Beyond Pluto in our Solar System is a region containing more than 70,000 large comets, and hundreds of millions of smaller ones, called the "Kuiper belt". The image [...] shows dust particles that the astronomers believe are analogous to our Kuiper belt at the same distance from Epsilon Eridani as the Kuiper belt is from our Sun. Although the image cannot reveal comets directly, the dust that is revealed is believed to be debris from comets."

"Epsilon Eridani's inner region contains about 1,000 times more dust than our Solar System's inner region, which may mean it has about 1,000 times more comets [...]. Epsilon Eridani is believed to be only 500 million years to 1 billion years old; our Sun is estimated to be 4.5 billion years old, and its inner region is believed to have looked very similar at that age."

"The new image -- which is from short-radio wavelengths, and is not an optical picture -- was obtained using the 15-meter James Clerk Maxwell Telescope [JCMT] at the Mauna Kea Observatory in Hilo, Hawaii. The JCMT is the world's largest telescope dedicated to the study of light at "submillimeter" wavelengths. The [...] camera called SCUBA (Submillimeter Common User Bolometer Array), which was built by the Royal Observatory in Edinburgh (which is now the UK Astronomical Technology Centre). SCUBA uses detectors cooled to a tenth of a degree above absolute zero (-273 degrees Celsius) to measure the tiny amounts of heat emission from small dust particles at a wavelength close to one-millimeter."

"The implication is that if there is one system similar to ours at such a close star, presumably there are many others, [...] In the search for life elsewhere in the universe, we have never known where to look before. Now, we are closing in on the right candidates in the search for life."

"A region near the star that is partially evacuated indicates that planets may have formed, [...] the presence of planets is the most likely explanation for the absence of dust in this region because planets absorb the dust when they form."

"There may be a planet stirring up the dust in the ring and causing the bright spot, or it could be the remnants of a massive collision between comets."

CARMA-7
At their origin lies an extremely young star — called a protostar — that is beginning the long journey to becoming a star much like the Sun.

The infant star, known as CARMA-7, and its jets are located approximately 1400 light-years from Earth within the Serpens South star cluster. This dense cluster, predictably found in the constellation of Serpens (The Serpent), is home to at least 30 more protostars that are sparking into existence in close proximity, providing astronomers with a perfect laboratory in which to study the interactions between stars and their environment.

The first steps of a star’s life are still poorly understood, but astronomers concluded that these knotted, smoky jets are caused by periodic outbursts of gas, ejected at tremendous speeds from CARMA-7 into its surroundings. These outbursts are triggered by material infalling onto the protostar from an orbiting disc. As the jets speed away from their infant star, they collide with interstellar material causing them to slow and spread out. One day, that material may collapse and form yet another generation of stars.

CW Leonis
"This Herschel image shows IRC+10216, also known as CW Leonis -- a star rich in carbon where astronomers were surprised to find water. This color-coded image shows the star, surrounded by a clumpy envelope of dust, at three infrared wavelengths, taken by Herschel's spectral and photometric imaging receiver (SPIRE) and photodetector array camera and spectrometer (PACS). Blue shows light of 160 microns; green shows 250 microns; and red shows 350 microns."

Betelgeuse
This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available. Betelgeuse is one of the largest stars currently known — with a radius around 1400 times larger than the Sun’s in the millimeter continuum. About 600 light-years away in the constellation of Orion (The Hunter), the red supergiant burns brightly, causing it to have only a short life expectancy. The star is just about eight million years old, but is already on the verge of becoming a supernova. When that happens, the resulting explosion will be visible from Earth, even in broad daylight. The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface. These features help to explain how the star is shedding gas and dust at tremendous rates (eso0927, eso1121). In this picture, ALMA observes the hot gas of the photosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric. Scientifically, ALMA can help us to understand the extended atmospheres of these hot, blazing stars.

PDS 70c
The image shows this planet and its disc centre-front, with the larger circumstellar ring-like disc taking up most of the right-hand side of the image. The dusty circumplanetary disc is as large as the Sun-Earth distance and has enough mass to form up to three satellites the size of the Moon.

Molecular clouds
"Using the Submillimeter Array, a set of eight radiotelescopes atop Mauna Kea in Hawaii, [it was] found that G0.253+0.016 possesses very few ultra-dense nuggets that could collapse to form stars."

"This image [at right] from the APEX telescope, of part of the Taurus Molecular Cloud, shows a sinuous filament of cosmic dust more than ten light-years long. In it, newborn stars are hidden, and dense clouds of gas are on the verge of collapsing to form yet more stars. The cosmic dust grains are so cold that observations at submillimetre wavelengths, such as these made by the LABOCA camera on APEX, are needed to detect their faint glow. This image shows two regions in the cloud: the upper-right part of the filament shown here is Barnard 211, while the lower-left part is Barnard 213."

"The submillimetre-wavelength observations from the LABOCA camera on APEX, which reveal the heat glow of the cosmic dust grains, are shown here in orange tones. They are superimposed on a visible-light image of the region, which shows the rich background of stars. The bright star above the filament is φ Tauri."

Star-forming regions
"Observations made with the APEX telescope in submillimetre-wavelength light at a wavelength of 870 µm reveal the cold dusty clouds from which stars form in the Carina Nebula. This site of violent star formation, which plays host to some of the highest-mass stars in our galaxy, is an ideal arena in which to study the interactions between these young stars and their parent molecular clouds."

"The APEX observations, made with its LABOCA camera, are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory. The result is a dramatic, wide-field picture that provides a spectacular view of Carina’s star formation sites. The nebula contains stars equivalent to over 25 000 Suns, and the total mass of gas and dust clouds is that of about 140 000 Suns."

L1448 IRS3B
For the first time, astronomers have seen a dusty disc of material around a young star fragmenting into a multiple star system. This image comprises new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), Chile, and reveals the process in action!

Stars form in cosmic clouds of gas and dust, when the thin material in the clouds collapses gravitationally into denser cores that in turn draw additional material inward. The infalling material forms a rotating disc around the young star, and is slowly consumed. Eventually, the young star gathers enough mass to create the necessary temperatures and pressures at its centre to trigger nuclear fusion.

Stars that have no companion — such as the Sun — are not as common as we once thought. In fact, almost half of the stars in our galaxy have at least one companion, and some are more sociable still! Previous studies have indicated that the stars in multiple systems tend to be either relatively close to each other, within about 500 times the Earth-Sun distance (known as an Astronomical Unit or AU), or significantly further apart, at over 1000 AU.

Given these wildly different distances, scientists concluded that there were two main mechanisms producing multiple star systems — either the original cloud collapsed unstably and fragmented, each subsequent fragment crumpling to form a new star, or the rotating disc around an existing star fragmented, with the same result. Systems with larger separations likely formed via the former process (as recent observational studies have suggested), and closer-knit stellar families via the latter (although there was limited evidence of this process).

New data from ALMA have now offered observational evidence of this conclusion. This image shows the second process in action, as seen in the young triple star system L1448 IRS3B. The trio are still deeply embedded within their parent cloud in the constellation of Perseus, some 750 light-years from Earth, and are hungrily feeding from material in the surrounding disc. ALMA has revealed this disc to have a spiral structure, a feature that indicates gravitational instability.

HD 181327
Using 39 of the 66 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), located 5000 metres up on the Chajnantor plateau in the Chilean Andes, astronomers have been able to detect carbon monoxide (CO) in the disc of debris around an F-type star. Although carbon monoxide is the second most common molecule in the interstellar medium, after molecular hydrogen, this is the first time that CO has been detected around a star of this type. The star, named HD 181327, is a member of the Beta Pictoris moving group, located almost 170 light-years from Earth.

Until now, the presence of CO has been detected only around a few A-type stars, substantially more massive and luminous than HD 181327. Using the superb spatial resolution and sensitivity offered by the ALMA observatory astronomers were now able to capture this stunning ring of smoke and map the density of the CO within the disc.

The study of debris discs is one way to characterize planetary systems and the results of planet formation. The CO gas is found to be co-located with the dust grains in the ring of debris and to have been produced recently. Destructive collisions of icy planetesimals in the disc are possible sources for the continuous replenishment of the CO gas. Collisions in debris discs typically require the icy bodies to be gravitationally perturbed by larger objects in order to reach sufficient collisional velocities. Moreover, the derived CO composition of the icy planetesimals in the disc is consistent with the comets in our Solar System. This possible secondary origin for the CO gas suggests that icy comets could be common around stars similar to our Sun which has strong implications for life suitability in terrestrial exoplanets.

Milky Way
"The centre of our Galaxy, the Milky Way, lies 27,000 light years from Earth. [The Submillimetre Common User Bolometer Array] SCUBA shows us [in the image above] an exotic region of gas clouds, bubbles, and threads, shaped by stars, supernovae, and magnetic fields. The view is blocked at optical wavelengths by the intervening dust. Credit: D. Pierce-Price et al."

"This is a colour composite image [at right] of the central region of our Milky Way galaxy, about 26 000 light years from Earth. Giant clouds of gas and dust are shown in blue, as detected by the LABOCA instrument on the Atacama Pathfinder Experiment (APEX) telescope at submillimetre wavelengths (870 micron). The image also contains near-infrared data from the 2MASS project at K-band (in red), H-band (in green), and J-band (in blue). The image shows a region approximately 100 light-years wide."

NGC 1087
This image of the nearby galaxy NGC 1087 was obtained by combining observations taken with the Multi-Unit Spectroscopic Explorer (MUSE) on ESO’s Very Large Telescope (VLT) and with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. NGC 1087 is a spiral galaxy located approximately 80 million light-years from Earth in the constellation Cetus. The image is a combination of observations conducted at different wavelengths of light to map stellar populations and gas. ALMA’s observations are represented in brownish-orange tones and highlight the clouds of cold molecular gas that provide the raw material from which stars form. The MUSE data show up mainly in gold and blue. The bright golden glows map warm clouds of mainly ionised hydrogen, oxygen and sulphur gas, marking the presence of newly born stars, while the bluish regions reveal the distribution of slightly older stars.

Phantom Galaxy
Webb’s sharp vision has revealed delicate filaments of gas and dust in the grandiose spiral arms which wind outwards from the centre of this image. A lack of gas in the nuclear region also provides an unobscured view of the nuclear star cluster at the galaxy's centre.

M74 is a particular class of spiral galaxy known as a ‘grand design spiral’, meaning that its spiral arms are prominent and well-defined, unlike the patchy and ragged structure seen in some spiral galaxies. The Phantom Galaxy is around 32 million light-years away from Earth in the constellation Pisces, and lies almost face-on to Earth. This, coupled with its well-defined spiral arms, makes it a favorite target for astronomers studying the origin and structure of galactic spirals.

Webb gazed into M74 with its Mid-InfraRed Instrument (MIRI) in order to learn more about the earliest phases of star formation in the local Universe. These observations are part of a larger effort to chart 19 nearby star-forming galaxies in the infrared by the international PHANGS collaboration. Those galaxies have already been observed using the Hubble Space Telescope and ground-based observatories. The addition of crystal-clear Webb observations at longer wavelengths will allow astronomers to pinpoint star-forming regions in the galaxies, accurately measure the masses and ages of star clusters, and gain insights into the nature of the small grains of dust drifting in interstellar space.

Hubble observations of M74 have revealed particularly bright areas of star formation known as HII regions. Hubble’s sharp vision at ultraviolet and visible wavelengths complements Webb’s unparalleled sensitivity at infrared wavelengths, as do observations from ground-based radio telescopes such as the Atacama Large Millimeter/submillimeter Array, ALMA. By combining data from telescopes operating across the electromagnetic spectrum, scientists can gain greater insight into astronomical objects than by using a single observatory — even one as powerful as Webb! MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (the MIRI European Consortium) in partnership with JPL and the University of Arizona.

Whirlpool Galaxy
The image at right is a "composite image of the Whirlpool Galaxy (also known as M51). The green image is from the Hubble Space Telescope and shows the optical wavelength. The submillimetre light detected by SCUBA-2 is shown in red (850 microns) and blue (450 microns). The Whirlpool Galaxy lies at an estimated distance of 31 million light years from Earth in the constellation Canes Venatici."

SMM J2135-0102
"This composite image [at right] shows the discovery of the distant galaxy SMM J2135-0102. Left : a view of galaxy cluster MACS J2135-010217 (centre), which is gravitationally lensing SMM J2135-0102. Top right : SMM J2135-0102 was first discovered in submillimetre-wavelength observations (shown in red) with the LABOCA camera on the Atacama Pathfinder Experiment (APEX) telescope. Bottom right : follow-up observations with the Submillimeter Array (in red) revealed the clouds where stars are forming in the galaxy with great precision. Our view of the galaxy is magnified by gravitational lensing, which also produces a doubling of the image ; the apparent eight regions in the Submillimeter Array observations actually represent four distinct regions of star formation in the galaxy."

NGC 5643
This galaxy is located 55 million light-years from Earth in the constellation of Lupus (The Wolf), and is known as a Seyfert galaxy. Seyfert galaxies have very luminous centres — thought to be powered by material being accreted onto a supermassive black hole lurking within — that can also be shrouded and obscured by clouds of dust and intergalactic material.

As a result, it can be difficult to observe the active centre of a Seyfert galaxy. NGC 5643 poses a further challenge; it is viewed at a high inclination, making it even trickier to view its inner workings. However, scientists have used the Atacama Large Millimeter/submillimeter Array (ALMA) together with archival data from the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope to reveal this view of NGC 5643 — complete with energetic outflowing ionised gas pouring out into space.

These impressive outflows stretch out on either side of the galaxy, and are caused by matter being ejected from the accretion disc of the supermassive black hole at NGC 5643’s core. Combined, the ALMA and VLT data show the galaxy’s central region to have two distinct components: a spiraling, rotating disc (visible in red) consisting of cold molecular gas traced by carbon monoxide, and the outflowing gas, traced by ionised oxygen and hydrogen (in blue-orange hues) perpendicular to the inner nuclear disc.

Interacting galaxies
While galaxy collisions of this type are not uncommon, only a few galaxies with eye-like, or ocular, structures have been observed. The paucity of these features is likely due to their very ephemeral nature — ocular structures like these tend to only last for several tens of millions of years, which is merely the blink of an eye in a galactic lifetime.

These two galaxies are named IC 2163 (left) and NGC 2207 (right) — IC 2163 displays the ocular structure in this image. The duo lies approximately 114 million light-years from Earth in the direction of the constellation of Canis Major (The Greater Dog).

The galaxies have brushed past each other — scraping the outer edges of their spiral arms —with IC 2163 passing behind NGC 2207. This glancing collision triggered a tsunami of stars and gas in IC 2163, with material in the outer portions of the disc of the galaxy travelling inwards This colossal wave of material decelerated rapidly moving from the outer to the inner edge of the eyelids and crashed midway through the galaxy’s disc, producing dazzling ribbons of intense star formation and compressed ridges of gas and dust that resemble a pair of cosmic “eyelids”.

Locations on Earth
The "solar submillimeter telescope [(SST) is] at the El Leoncito Observatory located at 2550 m altitude in the Argentina Andes. The SST has a 1.5 m reflector with four 212 GHz and two 405 GHz radiometers operating simultaneously with 5 ms time resolution. The main-beam cluster consists of three 212 GHz beams (about 4 half-power beamwidth) partially overlapping each other and one 405 GHz beam (about 2) in the center of the three".

At left is the Swedish-ESO 15m Submillimeter Telescope (SEST) at ESO's La Silla Observatory, located on the outskirts of the Chilean Atacama Desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres.

Recent history
The recent history period dates from around 1,000 b2k to present.

The Kulmhotel Gornergrat, atop Gorgergrat, which is both mountain and ski slope, is also home to two observatories. The Kölner Observatorium für SubMillimeter Astronomie (KOSMA) [at right] is a 3-m radio telescope located at 3,135 m on Gornergrat near Zermatt (Switzerland) in the southern tower (nearest to the camera).

"Because of the good climatic conditions at the altitude of 3135 m (10285 ft), astronomical observatories have been located in both towers of the “Kulmhotel” at Gornergrat since 1967. In 1985, the KOSMA telescope was installed in the southern tower by the Universität zu Köln and, in the course of 1995, replaced by a new dish and mount."

"The KOSMA telescope with its receivers and spectrometers was dedicated to observe interstellar and atmospheric molecular lines in the millimeter and submillimeter wavelength range. After 25 years of a successful era came to an end (June 2nd, 2010). The 3m KOSMA Radio Telescope left the Gornergrat and joined his long journey to Yangbajing / Lhasa / Tibet."

"Chinese and German scientists are establishing an astronomical observatory in a Tibetan county 4,300 meters above sea level."

"Tibet is an ideal location because the water deficit in its air ensures superb atmospheric transparency and creates a comparatively stable environment for research in the areas of astrophysics, high-energy and atmospheric physics."

"The observatory would house a KOSMA 3-meter sub-millimeter-wave telescope, the first of its kind to be used in general astronomical observation in China."

"It will boost China's research capacity in sub-millimeter astronomy and will hopefully provide a platform for astronomical experiments and training on the plateau and in the polar regions."

"Sub-millimeter astronomy refers to astronomical observations carried out in the region of the electromagnetic spectrum with wavelengths from approximately 0.3 to 1 millimeter."

Catalogs
The submillimeter, millimeter, and microwave spectral line catalog is "a computer-accessible catalog of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10 000GHz (ie wavelengths longer than 30μm)."

Telescopes
"Bolometers are currently the best choice for sensitive direct detection of radiation at wavelengths between 200 μm and 2 mm (e.g., Refs. 1 and 2). [...] a bolometer operates by measuring the heating due to absorbed energy [... It] is sensitive to any type of energy reaching the absorber. [Filtering does] not prevent cosmic, gamma, and x rays from reaching a bolometer."

At right is the Atacama Submillimeter Telescope Experiment (ASTE). It "is a joint project between Japan and Chile to install and operate a high-precision, 10 m telescope in the Atacama desert for exploration of the southern sky in the sub-millimeter." ASTE has a main reflector surface accuracy of 19 µm (RMS) and a pointing accuracy of 1.2" (RMS) [for both azimuth and elevation]."

ASTE is located at Pampa la Bola (4860 masl) "in the Atacama desert of Northern Chile."

Balloons
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a submillimeter telescope that hangs from a high altitude balloon. It has a 2 meter primary mirror that directs light into bolometer arrays operating at 250, 350, and 500 µm. ... BLAST's primary science goals are:
 * Measure photometric redshifts, rest-frame FIR luminosities and star formation rates of high-redshift starburst galaxies, thereby constraining the evolutionary history of those galaxies that produce the FIR/submillimeter background.
 * Measure cold pre-stellar sources associated with the earliest stages of star and planet formation.
 * Make high-resolution maps of diffuse galactic emission over a wide range of galactic latitudes.

High-altitude balloons and aircraft can get above much of the atmosphere. The BLAST experiment and SOFIA are two examples, respectively, although SOFIA can also handle near infrared observations.

At left above "NASA's balloon-carried BLAST sub-millimeter telescope is hoisted into launch position on Dec. 25, 2012, at McMurdo Station in Antarctica on a mission to peer into the cosmos." The giant helium-filled balloon is slowly drifting about 36 km above Antarctica. It was "[l]aunched on Tuesday (Dec. 25) from the National Science Foundation's Long Duration Balloon (LDB) facility ... This is the fifth and final mission for BLAST, short for the Balloon-borne Large-Aperture Submillimeter Telescope. ... "BLAST found lots of so-called dark cores in our own Milky Way — dense clouds of cold dust that are supposed to be stars-in-the-making. Based on the number of dark cores, you would expect our galaxy to spawn dozens of new stars each year on average. Yet, the galactic star formation rate is only some four solar masses per year." So why is the stellar birth rate in our Milky Way so low? Astronomers can think of two ways in which a dense cloud of dust is prevented from further contracting into a star: turbulence in the dust, or the collapse-impeding effects of magnetic fields. On its new mission, BLAST should find out which process is to blame. ... [The 1800-kilogram] stratospheric telescope will observe selected star-forming regions in the constellations Vela and Lupus."

Observing sites
The most significant limitation to the detection of astronomical emission at submillimetre wavelengths with ground based observatories is atmospheric emission, noise and attenuation. Like the infrared, the submillimetre atmosphere is dominated by numerous water vapour absorption bands and it is only through "windows" between these bands that observations are possible. The ideal submillimetre observing site is dry, cool, has stable weather conditions and is away from urban population centres. There are only a handful of such sites identified, they include Mauna Kea (Hawaii, USA), the Llano de Chajnantor Observatory on the Atacama Plateau (Chile), the South Pole, and Hanla (India). Comparisons show that all four sites are excellent for submillimetre astronomy, and of these sites Mauna Kea is the most established and arguably the most accessible. The Llano de Chajnantor Observatory site hosts the Atacama Pathfinder Experiment (APEX), the largest submillimetre telescope operating in the southern hemisphere, and the world's largest ground based astronomy project, the Atacama Large Millimeter Array (ALMA), an interferometer for submillimetre wavelength observations made of 54 12-metre and 12 7-metre radio telescopes. The Submillimeter Array (SMA) is another interferometer, located at Mauna Kea, consisting of eight 6-metre diameter radio telescopes. The largest existing submillimetre telescope, the James Clerk Maxwell Telescope, is also located on Mauna Kea.

The Caltech Submillimeter Observatory (CSO) is a 10.4-metre (34 ft) diameter submillimeter wavelength telescope situated alongside the 15-metre (49 ft) James Clerk Maxwell Telescope (JCMT) [below] at Mauna Kea Observatory. It is engaged in submillimeter astronomy, of the terahertz radiation band. The CSO and JCMT were combined to form the first submillimeter interferometer.

The Submillimeter Telescope (SMT), formerly known as the Heinrich Hertz Submillimeter Telescope, is a submillimeter wavelength radio telescope located on Mount Graham, Arizona. It is a 10-meter-wide parabolic dish inside a building to protect it from bad weather. The building front doors and roof are opened when the telescope is in use. The dryness of the air around and above Mt. Graham is particulatly vital for [Extremely high frequency] EHF (extremely low wavelength radio) and far-infrared observations - a region of the spectrum where the electromagnetic waves are strongly attenuated by any water vapor or clouds in the air.

The fourth and fifth images at right are the submillimeter array, or the Smithsonian Astrophysical Observatory Submillimeter Array, (SMA) located at Mauna Kea Observatory on Mauna Kea, Hawaii.

Satellites
Space-based observations at the submillimetre wavelengths remove the ground-based limitations of atmospheric absorption.

The Submillimeter Wave Astronomy Satellite (SWAS) [is in] low Earth orbit to make targeted observations of giant molecular clouds and dark cloud cores. The focus of SWAS is five spectral lines: water (H2O), isotopic water (H218O), isotopic carbon monoxide (13CO), molecular oxygen (O2), and neutral carbon (C I).

The European Space Agency Herschel Space Observatory deploys the largest mirror ever launched into space and studies radiation in the far infrared and submillimetre wavebands. Rather than an Earth orbit, Herschel entered into a Lissajous orbit around L2, the second Lagrangian point of the Earth-Sun system. L2 is located approximately 1.5 million km from Earth and the placement of Herschel there lessens the interference by infrared and visible radiation from the Earth and Sun. Herschel's mission focuses primarily on the origins of galaxies and galactic formation.

The observatory will sift through star-forming clouds—the "slow cookers" of star ingredients—to trace the path by which potentially life-forming molecules, such as water, form.

Hypotheses

 * 1) An image of the Sun at submillimeter wavelengths should be possible.

A control group for general submillimeter astronomy may start with the observing characteristics and limitations of the James Clerk Maxwell Telescope. A satellite-based observational platform that may serve as part of a control group may be the Submillimeter Wave Astronomy Satellite.