Stars and Magnitude

What is the luminosity of a star?

• The total amount of heat it generates from nuclear reactions.

• The total amount of light it reflects from other stars.

• The total amount of light it radiates per unit of time

• The total amount of mass it contains.

What is the scale used to measure the brightness of stars as viewed form Earth?

• absolute magnitude scale

• luminosity scale

• apparent magnitude scale

• intensity scale

What is the defintion of absolute magnitude?

• The mangitude of all the energy being emitted from a star

• The brightness of a star as it appears on the H-R diagram

• The brightness of a star as viewed from a distance of 1 parsec

• The brightness of a star as viewed from 32.6 LY

In the formula for absolute brightness: M= m + 5 - (5 (log D)), D equals what?

• A measure of the density of a the star

• A measure of the temperature of the star as detected from Earth

• A measure of the distance of the star from Earth in parsecs

• A measure of the size of the star as seen from Earth

What is the absolute magnitude (M) of a star that has an apparent magnitude of 0.3.67, and is at a distance from Earth of 3.5 parsecs?

M = m + 5 - (5 (log D))

• -6.12

• 0.6

• 2.6

• 12.1

Which type of star has a lower apparent magnitude?

• Stars that are closer to Earth

• Stars that are farther from Earth

• Red giant stars

What does a negative value of apparent magnitude indicate?

• average brightness

• exceptionally dim

• no light

• exceptionally bright

Why do supergiant stars appear more bright than all the ther stars (except Supernovas)?

• Their density is the highest of all the star stages

• Their surface temperature is the hottest

• Their size makes them easier to see

Which star has a higher luminosity: a star with absolute magnitude -5 or a star with absolute magnitude 2?

• star with absolute magnitude 7

• star with absolute magnitude 0

• star with absolute magnitude 10

• star with absolute magnitude -5