Exam 12: Evolution of Low-Mass Stars

You observed three different star clusters and found that the main-sequence turnoff stars in cluster 1 had spectral type A,the main-sequence turnoff stars in cluster 2 had spectral type B,and the main-sequence turnoff stars in cluster 3 had spectral type G.Which star cluster is the oldest?

Which point on the figure below represents the location on the H-R diagram where the star is on the horizontal branch?

What is a planetary nebula?

The correct order of evolutionary stages for a solar mass star is:

Which figure below represents the youngest star cluster?

A low-mass main-sequence star's climb up the red giant branch is halted by:

When a G2 star leaves the main sequence,its luminosity:

Explain the significance of Roche lobes in a binary system.

When a star depletes its core supply of hydrogen,________ dominates in the core and ________ dominates in the atmosphere.

Explain the two different forms of pressure that support the core of a low-mass main-sequence star and the core of a low-mass red giant star?

A Type Ia supernova occurs when a white dwarf exceeds a mass of:

The figure below plots the chemical composition of the Sun as a function of radius for three different times.Which graph represents the correct chemical composition just prior to the Sun becoming a red giant?

Why are novae thought to be recurrent?

Calculate the main-sequence lifetimes of the following stars of different spectral types: B0 (18 M¤),B5 (6 M¤),A5 (2 M¤),F5 (1.3 M¤),and M0 (0.5 M¤).What trend do you notice in your results?

What ionizes the gas in a planetary nebula (see the image below)and makes it visible?

A main-sequence star is unique because:

A star like the Sun will lose about ________ of its mass before it evolves to become a white dwarf.

Why does the core of a main-sequence star have to be hotter to burn helium into carbon than hydrogen into helium?

About how long will a 2-M¤ star live as a main-sequence star?

A low-mass red giant star's energy comes from: