Exam 16: Evolution of Low-Mass Stars

Use the following graph and the relationship τ ∝ M/L to estimate the main-sequence lifetime of a star with a mass equal to 10 times that of the Sun.Note that the Sun's main-sequence lifetime is about 10¹⁰ years.

The more massive a star is,the more hydrogen it has to burn,and the longer its main-sequence lifetime lasts.

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

As a subgiant star becomes a red giant,its luminosity increases while its temperature remains approximately constant.What does this mean?

Pressure from degenerate electrons keeps the core of a red giant star from collapsing.

What would you need to measure about a planetary nebula to determine how long ago its parent star died?

One star in a binary will almost always become a red giant before the other because:

What is the radius of a red giant star that has a luminosity of 300 L_⨀ and a temperature of 4000 K? (Note that the temperature of the Sun is 5800 K. )

When a star depletes its core supply of hydrogen,_________ causes the core to collapse while increased gas _________ is exerted on the atmosphere.

In a white dwarf,what is the source of pressure that halts its contraction as it cools?

The Sun will likely stop being a main-sequence star in:

What is a planetary nebula?

For low-mass main-sequence stars in hydrostatic equilibrium,at any interior radius there exists a balance between the downward gravitational force at that radius and:

What are two ways that Type I supernovae can be produced?

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 and makes it visible?

A Type I supernova has a luminosity of approximately:

Helium burns in the core of a horizontal branch star via _________ and produces _________.

What factor is most important in determining a star's position on the main sequence and subsequent evolution?

What stops a red giant from cooling to continuously lower temperatures,and why?