Astro Quiz 4

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The average density of the interstellar medium is

1 atom/cm^3

A type Ia supernova can be as luminous as

10 billions suns

A 10 M_SUN will evolve through the same phases as a...

20 M_SUN star

We observe neutral hydrogen gas using

21-cm emission

The sun will become a red giant star in about

5 billion years

_______ keeps the core of a red giant star from collapsing.

Degenerate pressure from electrons.

As a main-sequence star burns its core supply of hydrogen, what happens?

Helium builds up in the core

If a main-sequence star's core temperature increased, fusion reaction rates would _____ because the protons would be moving _____.

Increase; faster

What factor is most important in determining a stars position on the main sequence and its subsequent evolution?

Mass

What critical event transforms a protostar into a normal main-sequence star?

Nuclear Fusion begins in the core

What primarily makes it difficult to observe the process of star formation?

Star formation occurs in dusty regions

When radiation from an object passes through the interstellar medium

The object appears redder and dimmer

Dust in the ISM appears dark in _________ wavelengths and bright in _________ wavelengths.

Visible; infrared

As a protostar contracts,

either the luminosity decreases or the temperature increases

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

electrons packed so closely that they become incompressible.

For an object in hydrostatic equilibrium, if the temperature inside the object were to increase, the object would.

expand

When looking at the space between stars, what are you most likely to see?

gas

Degenerate refers to a state of matter at

high density

Brown dwarfs are considered failed stars because

hydrogen fusion never begins in their cores

molecular hydrogen atoms can be found

in dense clouds where they are shielded from stellar radiation

As a protostar is evolving, its temperature

increases due to kinetic energy of infalling material.

An asymptotic giant branch star loses mass to the interstellar medium because

it has low surface gravity

Interstellar extinction refers to

light being absorbed by dust in interstellar space

A nova is the result of which explosive situation?

mass transfer onto a white dwarf

The ________ a main-sequence star is, the more hydrogen it has to burn, and the ______ its main-sequence lifetime.

more massive; shorter

Dust reddens starlight because it

preferentially affects light at visible and shorter wavelengths.

Molecular clouds, which have temperatures of around 10 K, are best observed at _____ wavelengths.

radio

What is a planetary nebula?

the ejected envelope of a giant star surrounding the remnant of a star

Stars evolve primarily because...

they use up the fuel in their cores.


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