Stars/Active regions/Quiz

Stellar active region is a lecture/article about an entity, source, and/or object observed on or near the surface of the Sun with radiation astronomy.

This is a TRACE image of the coronal arcade structure in the flare on Bastille Day, 1998. Credit: NASA.

It is also part of the course on the principles of radiation astronomy.

You are free to take this quiz is based on the lecture stellar active region at any time.

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1 Which of the following are radiation astronomy phenomena associated with the Sun?

ultraviolet emission
X-ray emission
gamma-ray emission
neutron emission
7Be emission
meteor emission

2 True or False, The Norikura Solar Observatory uses its own designations for solar active regions rather than those of other observatories or NOAA.


3 Which of the following is not a characteristic of solar active regions?

coronal clouds
spot central meridian passage
a surface coverage of at least 95%.

4 True or False, A dominant group with respect to stellar active regions differs from a control group in that it rules the treatment of the control group.


5 During the late 1600s the sunspot cycle lost its usual intensity and became what?

6 Evidence that demonstrates that a model or idea versus a control group is feasible is called a


7 True or False, Naked sunspots seen in Hα which are devoid of plage are never associated with coronal holes.


8 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 active regions

9 Complete the text:



originate in magnetically

around visible


10 True or False, A control group may be used in stellar active regions to demonstrate no effect or a standard effect versus a novel effort applied to a treatment group.


11 Complete the text:

A short or

realization of a certain

or idea to

a treament's feasibility for stellar active regions is called a proof of


12 True or False, "[A] spicule is a dynamic jet of about 500 km diameter in the chromosphere of [a star]."


13 When faculae are present, what characteristics are readily observed?

bright spots
bright patches
magnetic poles
arising in the photosphere
neon clouds

14 The population of coronal loops can be directly linked with the?

15 True or False, Coronal loops project into the coronal cloud, through the transition region and the chromosphere.


16 Which of the following is not a prominent contributor associated with a variable star?

star spots
chromospheric activity
brightness fluctuations
spot coverage fraction

17 In general there is no proper motion at all in the plage or the surrounding?

18 True or False, "Some prominences break apart and give rise to coronal mass ejections."


19 Complete the text:

A proof-of-concept structure, including a control group, consists of

, procedures, findings, and


20 True or False, A pure stellar active region involves no doing apart from itself.


21 Which of the following is not a phenomenon usually associated with regions?

a connected part of a space
a tract of land
definite extent
Van Maanen's star
temporal change in radiation flux

22 Complete the text:

"When a prominence is viewed from a different perspective so that it is against the

instead of against space, it appears

than the surrounding


23 True or False, In 1947, G. E. Kron proposed that starspots were the reason for periodic changes in brightness on blue dwarfs.


24 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

25 A Mt. Wilson spot number usually corresponds with which other region number?

26 True or False, Hale region numbers are greater for the same regions than NOAA numbers.


27 Which of the following active region phenomena have been observed on Proxima Centauri?

temperatures as high as 27 MK
quiescent X-ray luminosity comparable to the Sun
a surface coverage of about 88%
likely prominence

28 Solar observation is performed all around the surface of the Earth by?

29 True or False, The Kodaikanal Solar Observatory is a solar observatory owned and operated by the Indian Institute of Astrophysics.


30 Which of the following are phenomena usually associated with a heliostat?

geographic coordinates
a mirror which turns so as to keep reflecting sunlight toward a predetermined target
the target is usually stationary
computer control
a two-axis motorized system

31 Active regions are the result of enhanced what?

32 True or False, Most stellar flares and coronal mass ejections originate in magnetically inactive regions around visible sunspot groupings.


33 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

34 A super flare on the evening of August 28, 1859, was recorded by

35 True or False, The Ca XV emission line is a yellow coronal line at 569.4 nm.


36 Which of the following are characteristic of the first true astrophysical gamma-ray source?

a strong 2.223 MeV emission line
a solar flare
the formation of deuterium
the electron neutrino

37 Using a coordinate system, sunspot passage is generally noted by what meridian?

38 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."


39 Which geographical phenomena are associated with stellar active regions?

moving across the surface of the Sun or star
manifesting intense magnetic fields
a north geographic and magnetic pole
a prime meridian
average starspot latitudes
the solar or stellar equator

40 Coronal loops extend high into the corona, project through the chromosphere, and project through what above the photosphere?

41 True or False, Coronal loops populate both active and quiet regions of the solar surface.


42 Phenomena associated with nanoflares?

1017 Joules
very high X-ray emission from happening every 20 s
mass eruptions
active regions

43 Main sequence variable stars of late spectral types, usually K or M, exhibiting variations in luminosity due to rotation, starspots and other chromospheric activity are called.

44 True or False, RS Canum Venaticorum variables are close binary stars having active chromospheres which can cause large stellar spots.


45 Which of the following are observatories on Earth?

Chandra X-ray Observatory
Big Bear
the Hubble
Lomnický štít

46 Sayan Observatory is located in.

47 True or False, The solar neutron detector located at Mt. Norikura observatory, Japan, is made of plastic scintillators.


48 Which of the following are associated with the McMath-Pierce Solar Telescope?

a launch location
Kitt Peak National Observatory
a heliostat
a distinctive diagonal shaft that continues underground
a theoretical resolution of 0.07"
NOAA designations

49 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?

50 True or False, T Tauri stars are likely to have large areas of starspot coverage.


51 Which of the following observatories are solar observatories?

The Huairou Solar Observing Station in China
Mauna Loa Solar Observatory
Los Alamos National Solar Laboratory
National Solar Observatory
Mees Solar Observatory

52 About one third of ejecta observed by satellites at Earth is composed of what?

53 True or False, A spotless flare may occur in a plage region during its first rotation.


54 Which of the following are solar observatory satellites?

Einstein Observatory
High Energy Astronomy Observatory 1

55 Suborbital solar probing may be accomplished from different geographical locations using?

56 True or False, The Mauna Kea Observatories are used for scientific research across the electromagnetic spectrum from visible light to radio, and comprise the largest such facility in the world.


57 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

58 Yes or No, The purpose of a treatment group for stellar active regions is to describe natural processes or phenomena for the first time relative to a control group.



  1. Apparently the active region cycles of the Sun corresponds to the repeated conjunctions of Venus and Jupiter.

See also


{{Principles of radiation astronomy}}