Gowdy Modules 22-24 ( not done yet)

10-4.

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

10,000 parsecs. Yes. Multipy 10pc by 10 for each 5 units difference.

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

100,000 parsecs. Yes. 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

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

11. Yes. Two 5 magnitude differences give (1/100)×(1/100)=10-4 times the brightness.

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

16 Yes. 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. Yes. The standard 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. Yes. 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

100au

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?

100 parsecs. Yes. A difference of 5 magnitudes means multiply 10pc by 10. d=105/5×10pc.

Suppose that the color and behavior of a star identify it as a type that we know has absolute magnitude -3. If the star's apparent magnitude is found to be 2, how far away is it?

100 parsecs. Yes. A difference of 5 magnitudes means multiply 10pc by 10. d=105/5×10pc.

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 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. Yes. At 10pc, the absolute and apparent magnitudes are equal.

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?