Stars/X-ray classification/Quiz

X-ray classification of stars is a lecture in the X-ray astronomy of stars. It is part of the X-ray astronomy/Course.

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Quiz
{True or False, To emit X-rays a source must have some small amount of plasma near or above 106 K. + TRUE - FALSE
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{The Sun as a star has what geographical property? - it's a primordial population III star - it passes once a year across the Lockman Hole - silicates have been discovered in its interior structure - optical reflectance studies have found evidence of magnesium - it has a surface temperature of ~700 K + it has a longitude and latitude grid system for locating surface features
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{Yes or No, Only a plasma may be luminous. - Yes + No
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{Which of the following is not a phenomenon usually associated with sunspots? - solar photosphere - a hole in the granulated photosphere + production of 7Be - rotation - solar cycle - starspots - flip-flop cycle
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{True or False, Any object forming on a dynamical timescale, by gravitational instability, may be a star. + TRUE - FALSE
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{Which of the following is not a phenomenon associated with a flip-flop cycle? - active regions - hemisphere shifts - binary RS CVn stars - single stars - cyclical period + meridian passage
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{True or False, All gaseous bodies may be a star. - TRUE + FALSE
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{Complete the text: Most { stellar flares|solar flares|flares (i) } and { coronal mass ejections|CMEs (i) } originate in magnetically { active regions (i) } around visible { sunspot|starspot (i) } groupings.
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{True or False, An O class star is not hot enough on the surface of its photosphere to emit X-rays. + TRUE - FALSE
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{The population of coronal loops can be directly linked with the? { solar cycle (i) }
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{True or False, A spicule is a dynamic jet of about 500 km diameter in the chromosphere of a star. + TRUE - FALSE
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{Which of the following are associated with the stellar active region control group? + solar cycle - closed magnetic structures - solar wind + long-lived loop arcades + helmet streamers + the Sun
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{True or False, Coronal loops project into the coronal cloud, through the transition region and the chromosphere. + TRUE - FALSE
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{Active regions are the result of enhanced what? { magnetic fields (i) }
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{True or False, Stars of spectral classes F and G, such as our sun, have color temperatures that make them look "greenish". - TRUE + FALSE
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{Phenomena associated with nanoflares? + 1017 Joules + very high X-ray emission from happening every 20 s - flickerings - brightenings - mass eruptions + active regions
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{True or False, The photosphere of a star may be the result of omnidirectional incoming electrons. + TRUE - FALSE
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{About one third of ejecta observed by satellites at Earth is composed of what? { magnetic clouds (i) }
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{True or False, The Ca XV emission line is a yellow coronal line at 569.4 nm. + TRUE - FALSE
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{Which stars of the alpha Centauri system are known to have stellar active regions? + Proxima Centauri + Alpha Centauri B - Barnard's star - Alpha Centauri A + Rigel Kent + Alpha Centauri C - Alpha Centauri D
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{True or False, "75% of the naked sunspots represented the return of large dominant f spots which had been part of large active regions during previous rotations." - TRUE + FALSE
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{The type star that goes through fairly extreme changes of brightness: for instance, in 1952, its brightness increased by 75 times in only 20 seconds, is what star? { UV Ceti (i) }
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{True or False, T Tauri stars are likely to have large areas of starspot coverage. + TRUE - FALSE
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Hypotheses

 * 1) Stars that are in different classes based on their photosphere temperatures may be in the same class based on their X-ray spectra.