22

10-4. (The distance is the standard 10pc distance multiplied by 100. The brightness is then divided by 1002 or 10,000, which is the same as multiplying the absolute brightness by 1/10,000 or 10-4.)

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

10,000 parsecs.

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

100,000 parsecs. (d = 1020/5×10pc = 104×10pc)

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

10,000 parsecs. (That is the standard distance multiplied by 1000. Divide the absolute magnitude by 10002, which is the same as multiplying it by 10-6.)

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

11.

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

16. (Three 5 magnitude differences would give (1/100)×(1/100)×(1/100)=10-6 times the brightness.)

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

10 parsecs. (the std distance)

A star with a distance modulus of zero is at a distance of

of dazzling brightness.

A star with an absolute magnitude of 5.7 and an apparent magnitude of -1.2 would appear in our sky as a star

barely visible to the naked eye. (Apparent magnitude 5.7 is close to the limit.)

A star with an apparent magnitude of 5.7 and an absolute magnitude of -1.2 would appear in our sky as a star

standard candle.

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

100au (The distance is multiplied by 100, so divide the brightness by 100^2 or 10,000. That gives 1000/10,000 = 1/10 = 0.1.)

Cruising far from the Sun, we notice that the Sun's apparent brightness has dimmed to 0.1 watts per square meter. We know that the apparent brightness at a distance of 1au is 1000 watts per square meter. How far from the Sun are we?

Distant objects are not behaving the same as nearby objects.

Of all the things that might go wrong with distances found by using the method that astronomers refer to as the "distance ladder," which of these is the one that an astronomer would say is most likely?

100 parsecs. (A difference of 5 magnitudes means multiply 10pc by 10. d=10^(5/5)×10pc.)

Suppose that the color and behavior of a star identify it as a type that we know has absolute magnitude 4.8. If the star's apparent magnitude is found to be 9.8, how far away is it?

1.1 watts per square meter. (The distance was multiplied by 30, so the apparent brightness gets divided by 30×30 or 900. 1000/900 = 1.1)

The apparent brightness of our Sun 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

0.

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

absolute magnitude is known.

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

-1.5.

Which of the following magnitudes corresponds to the brightest star?

+5.6.

Which of the following magnitudes corresponds to the dimmest star?

Distant objects are similar to 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?"