Plasmas/Plasma objects/Coronal clouds/Quiz

Coronal clouds is a lecture and an article about a specific astronomical entity, a type of plasma meteor. It is also a part of the department of astronomy course on the principles of radiation astronomy.

This image is taken in Hα of the Sun and above showing a cloud above a sunspot. Credit: Alan Friedman.

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1 Yes or No, The Chamaeleon I cloud is a coronal cloud.


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

the color of the upper rim as seen from Earth
an excess brightness at or near the edge of the Sun
the iron XIV green line
neutron emission
polar coronal holes
meteor emission
changes in the line-blanketing

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

4 Which of the following is a prominent feature associated with solar clouds?

coronal mass ejections
magnetic clouds
coronal clouds
magnetic field lines

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


6 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%.

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

8 True or False, Coronal clouds are irregular objects suspended in the corona with matter streaming out of them into nearby active regions.


9 Which of the following are X-radiation astronomy phenomena associated with the Sun?

a core which emits neutrinos
a solar wind which emanates out the polar coronal holes
the barycenter for the solar system
polar coronal holes
coronal clouds
its position
temperatures at or above 1 MK

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


11 Which of the following are associated with X-radiation?

spans three decades in wavelength
spans three decades in frequency
spans three decades in energy
emitted by 26Al
coronal clouds
60 keV electromagnetic radiation
90 eV electromagnetic radiation
visually dark source

12 True or False, The Milky Way has its own coronal cloud.


13 Complete the text:

The photosphere of the Sun has an effective temperature of

yet its corona has an average temperature of

. The high temperature of the corona shows that it is heated by something other than direct

from the photosphere.

14 True or False, In a coronal cloud are magnetohydrodynamic plasma flux tubes along magnetic field lines.


15 Which of the following are X-ray astronomy phenomena that may be associated with the Sun?

coronal cloud
hot regions of 8–20 x 106 K
fluorescence of Jovian X-rays
X-rays from rings
collisions with the Jovian wind
soft X-ray emission
hard X-ray emission

16 True or False, The hot ionized medium (HIM) consists of a coronal cloud which emits X-rays.


17 Complete the text:

Discussion of the alternative hypothesis of cloud ejection from the equatorial layer of the Galaxy leads to the conclusion that the

halo must be highly

and that the coronal clouds are probably


18 True or False, 3C 295 is a galaxy cluster filled with a vast cloud of 50 MK gas and plasma.


19 Pick the following sources that are or are likely to contain a coronal cloud?

gamma-ray source
dark nebula
X-ray source
molecular cloud
soft X-ray emission source
hard X-ray emission

20 True or False, Coronal clouds, type IIIg, form in space above a spot area and rain streamers upon it.



  1. Solar flares occur before coronal clouds.

See also


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