Astronomy exam #4 module 22

A star at a distance of 1000pc should have an apparent brightness equal to its absolute brightness multiplied by what?

10^-4

Which of the following magnitudes corresponds to the dimmest star?

+5.6 because the highest magnitude is the dimmest.

Which of the following magnitudes corresponds to the brightest star?

-1.5 because negative numbers are brighter than bright.

A star with a distance modulus of zero is at a distance of ___ parsecs.

10 parsecs is the standard distance.

A star is observed to have an apparent brightness which is 10^-6 times its absolute brightness. How far away is it?

10,000 parsecs

A star is found to have an absolute magnitude of 4 and an apparent magnitude of 19. How far away is it?

10^15/5*10=10,000 parsecs

A star is found to have an absolute magnitude of 4 and an apparent magnitude of 24. How far away is it?

10^20/5*10= 100,000 parsecs

A star whose apparent brightness is 10^-4 times that of a first magnitude star would have a magnitude of ____.

11.

A star whose apparent brightness is 10^-6 times that of a first magnitude star would have a magnitude of ____.

16.

The apparent brightness of a star is roughly 1000 watts per square meter. At a distance of 30 times the Earth-Sun distance, the apparent brightness of our Sun would be what?

900. The distance was multiplied by 30, so the brightness gets divided by 30*30 or 900.

Absolute magnitude is -3 and the apparent magnitude is 2. How far away is it?

A difference of 5 magnitude= 10^5/5*10=100 parsecs

Absolute magnitude is 4.8 and the apparent magnitude is 9.8. How far away is it?

A difference of 5 magnitudes= 10^5/5*10=100 parsecs

What astronomers refer to as a "standard candle" is defined as a light source whose ____ is known.

Absolute magnitude is known

A star with an apparent magnitude of 5.7 and an absolute magnitude of 01.2 would appear in our sky as a star ____ visible to the naked eye.

Barely visible to the naked eye.

Which of these is the one that an astronomer would say is most likely?

Distant objects are not behaving the same as nearby objects.

Which of these answers describes the fundamental assumption that is behind all of the methods that astronomers refer to as the "distance ladder"?

Distant objects are similar to nearby objects.

Consider a light source whose absolute magnitude can be deduced from the properties of the light that reaches us from the source. Astronomers refer to this sort of subject as a what?

Standard Candle

A star with an absolute magnitude of 5.7 and an apparent magnitude of 01.2 would appear in our sky as a star ____ visible to the naked eye.

With dazzling brightness.

The distance modulus of a star at a distance of 10 parsecs would be ____.

Zero