1. Prepare your scantron:
Use
a pencil,
not a pen!
Fill in your name and fill the bubbles under
your name.
LAST NAME FIRST, First name second
Put your 4-digit code instead of “IDENTIFICATION NUMBER”.
--- (The last 4 digits of your OleMiss ID.)
Question # 1: answer A
Question # 2: answer B
Question # 3: answer A
Setup:
Reading assignment
Chapter 14 (The Sun): pp. 464 – 485
Test1 : Wednesday, Feb 13,
Have a scantron, pencil, and an ID!
Please take a moment to mute your cell phone!

2. This question counts double!
sec 8 9 11 7 10 4 1 2 3 13 6 12 25 30 35 40 14 19 16 15 17 18 45 20 5
Question 4
What is absolute magnitude?
A The diameter of a star in solar units.
B The apparent diameter of a star as seen from 10 parsecs.
C The magnitude of a star as seen from 33 light years.
D The brightness of a star when there is no extinction at all.
E The magnitude of a star as it appears in the sky.
Next question coming …

3. This question counts double!
sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 5
How bright would the Sun look in the sky
from a distance of 33 light years?
A -12mg
B 1mg
C 5mg
D 15mg
E Invisible: we cannot see that far.
Next question coming …

4. This question counts double!
sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 25 27 28 30 29 17 24 19 18 23 20 22 21
Question 6
The closest star to the Sun, Proxima Centauri, has an absolute magnitude of M = +14mg.
If you imagine it placed where the Sun is now,
would it look brighter, or fainter than the Sun?
A Ten thousand times brighter.
B Somewhat brighter.
C About the same.
D Somewhat fainter.
E Ten thousand times fainter.

5. Hydrogen (mainly) gas ball
The Sun
Sunspots An
Average
main
sequence
STAR
Surface features:
• sharp edge
(photosphere)
• sunspots
• limb darkening
(we see less deep
down at the edge)
Hydrogen (mainly) gas ball
Hot surface (6000 C)

6. What’s inside? In core: 4 H -> He (> 1 million K)
Radiation zone:
heat transfer
by radiation
Convection zone:
by convection
(“boiling”)
Photosphere:
visible edge
(6000 C)

7. Questions coming …

8. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 7
The photosphere is
A the name of all the hot parts of the Sun
B the name of the visible edge of the Sun
C the name of the central region of the Sun
D the name of a type of camera used to photograph the Sun.
E the name of a type of lens used to photograph the Sun.
Next question coming …

9. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 7
How hot is the photosphere?
A 600 K
B 6,000 K
C 60,000 K
D 600,000 K
E 6,000,000 K
Next question coming …

10. sec 10 9 11 13 14 8 12 7 2 1 3 4 6 5 15 17 26 25 27 28 30 29 16 24 19 18 23 20 22 21
Question 9
Why is the edge of the solar disk
darker than the middle?
A Because the photosphere is colder at the edge
of the Sun than in the middle.
B Because of the blurring effect of Earth’s atmosphere.
C Because we see deeper down in the middle of the Sun, where it is hotter.
D Because light is absorbed on the long way to the edge of the Sun.
E Because the middle of the Sun is closer to us than the edge.

11. Convection zone sticking out:
granulation
The Sun is
“boiling”:
Granules
live ~ 10 min
rising (hot)
and
sinking (“cold”)
matter
H image

12. Photosphere: “grainy”
Granules explained
Photosphere: “grainy”
Hot gas up
Cold gas down

13. Sunspots Undisturbed photosphere Penumbra Umbra (6000 K) (5000 K)
“Cold spots”
in the
photosphere
where
convection
is stopped
by the
magnetic field
Penumbra
(5000 K)
Umbra
(4000 K)

14. Sunspot details

15. What are sunspots? (1) Convection brings up magnetic field
(2) Strong field stops convection
(3) Spot cools off (only 4000 C)

16. Questions coming …

17. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 10
Where in the Sun is heat being produced?
A Everywhere inside the Sun.
B Only in the core (close to the center).
C Only in a narrow region close to the surface.
D In most of the Sun except in the convective outside region.
E Nowhere, because no more energy is being produced in the Sun now. It has been heated up once and it is only giving off its heat as it is cooling off.
Next question coming …

18. sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22
Question 11
What are sunspots?
A Regions on the Sun, hotter than the photosphere.
B Regions on the Sun, composed of dark substances.
C Regions on the Sun, colder than the photosphere.
D Holes in the surface of the Sun where we see deep into the Sun.
E Clouds floating over the photosphere.
Next question coming …

19. sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5
Question 12
Which of the following explains what granules are?
A The strong heat from below causes cracks on the
surface of the Sun.
B Rising hot bubbles reach the surface and glow until they cool down and sink.
C The magnetic field of the Sun makes gas glow when charged particles cross it.
D Clouds float over the photosphere.
E Asteroids keep falling into the Sun and burn up in the intense heat.
Next question coming …

20. sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5
Question 13
What causes the sunspots?
A The magnetic fields of the Sun deflects sunlight from
the spots, so they appear dark.
B The magnetic field of the Sun channels dark
substances into sunspots.
C The magnetic field of the Sun stops hot bubbles of gas from
rising, causing the region to cool off.
D The gravity of the Sun heats up the gas, which burns quickly
and the remaining ashes are dark.
E The shadow of the Moon is cast on the Sun, covering
dark regions.

21. Turn in your scantron now
personally!