Question

1. for a standard h - r diagram, what are the stars in the lower left region of the diagram?

main sequence stars
supergiants
giants
white dwarfs

1. stars on the upper left end of the main sequence differ from those on the lower right end in what way?

stars on the upper left end are less massive.
stars on the upper left end are more massive.
stars on the upper left end tend to be red in color.
stars on the upper left end are near the end of their life cycle

1. how do white dwarfs compare with supergiants, in terms of temperature and luminosity?

white dwarfs are cooler and have higher luminosity than supergiants.
white dwarfs are cooler and have lower luminosity than supergiants.
white dwarfs are warmer and have higher luminosity than supergiants.
white dwarfs are warmer and have lower luminosity than supergiants.

Explanation:

1. In a standard Hertzsprung - Russell (H - R) diagram, white dwarfs are located in the lower left region. They are hot (high temperature) but have low luminosity due to their small size.
2. On the main sequence of an H - R diagram, stars on the upper left end are more massive. They are hotter, more luminous, and have shorter lifetimes compared to stars on the lower right end.
3. White dwarfs are small, hot stars with low luminosity. Supergiants are large, very luminous stars. White dwarfs are warmer (higher surface temperature in many cases) but have lower luminosity than supergiants.

Answer:

1. White dwarfs
2. Stars on the upper left end are more massive.
3. White dwarfs are warmer and have lower luminosity than supergiants.