25.Why are Sunspots a darker color (i.e. cooler)? Select one: a. Magnetic fields

Question

25.Why are Sunspots a darker color (i.e. cooler)? Select one:

a. Magnetic fields increase convection.

b. The cool material falls onto the Sun from comets.

c. Magnetic fields suppress convection.

d. Cool blobs of helium gas float up from the core.

26. A 3 solar mass black hole has an event horizon of Select one:

a. 9 km

b. 1 km

c. 3 km

d. 1/3 km

e. 1/9 km

27. A binary system is discovered. All that we observed is that star A is a red giant, and star B is a white dwarf. Which of the following do we NOT know about the system? Select one:

a. The most massive star when the binary was formed.

b. The star with the highest surface temperature.

c. The distance to the binary

d. The star with the smallest radius.

29.A 1 solar mass star is dead. How did it move on the HR diagram? Select one:

a. Up to the left, then back down to the main sequence, then to the upper right, then down to the bottom of the main sequence.

b. Doesn’t move at all.

c. Up to the upper right, then to the left, then up to the right, then down to the bottom middle.

d. Up along the main sequence of stars.

e. Down to the bottom middle quickly.

31.Sirius currently has a parallax of 0.38 arcseconds. If it were 2 times farther away, it would have a parallax of Select one:

a. one half, 0.19 arcseconds

b. four times, 1.52 arcsconds

c. one quarter, 0.095 arcseconds

d. twice, 0.76 arcseconds

e. parallax does not change, so 0.38 arcseconds

32.Where is a main sequence 25 solar mass star on the HR diagram? Select one:

a. Lower left

b. middle

c. Lower right

d. Upper left

e. Upper right

33.When the Sun dies it will Select one:

a. explode away its outer envelope and reveal a white dwarf.

b. blow off its envelope and reveal a neutron star.

c. Wait a minute. The Sun does not die exactly. The Sun's end will depend on its final mass and since it is still accreting material from our molecular cloud over the next 5 billion years, we will have to wait and see.

d. explode away its outer envelope and reveal a neutron star.

e. blow off its envelope and reveal a white dwarf.

Explanation / Answer

25. Dark spots are darker because they are much cooler than rest of the sun but still it is hot and made up of helium

26 It is equal to 3 *Mbh

= 3*3

=9 is the event horizon

27.option a is the right answer. As the binary system in red and dwarf star represent a 1 and 0 as dwarf star is the last stage of star life cycle

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.