Exam 11: Measuring the Stars: Giants, Dwarfs, and the Main Sequence

A star both twice the diameter and twice the temperature of our Sun would be _ times more luminous than our Sun; in fact, Vega fits this description well.

Two stars are both spectral type K2V; if the closer is magnitude +3.7, and the fainter is magnitude +8.7, then the brighter star is about times closer.

What percentage of stars lie on the main sequence? Why?

The strongest lines present in spectral class A stars are absorption lines of

Stellar masses are determined by observing stars.

High mass stars are typically found on the of the main sequence.

A G2V star would be the same temperature as a G2Ib star, but much smaller and less luminous.

What is the relationship between a star's mass and its lifetime?

To find the distance of nearby stars, we use their parallaxes obtained over - month intervals.

What role does hydrogen play in spectral classification?

White dwarfs lie on the lower left portion of the H- R diagram.

Molecular lines, such as TiO, are only found in very hot stars.

The main sequence is luminosity class V.

Why can the Hubble Space Telescope give us better direct measurements of star diameters than larger Earth- based telescopes can?

A star's parallax is found by using the spectral lines to estimate the spectral class and luminosity of distant stars.

Hydrogen lines are weak in M class stars because they have much less of it than do A class stars.

Of all the stars in the sky, Barnard's star, the next closest beyond Alpha Centauri, appears to move the fastest.

Discuss the mass, temperature, color and size of an M3V star, compared to the Sun.

A 3rd magnitude star appears 2.5 times brighter than a 4th magnitude star.

If its parallax is 1", then the distance to the star is _ light- years.