Astronomy Exam 3

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How long does it take light to get from the core of the Sun to its surface?

500,000 years

surface temperature of the Sun

5700 K

The temperature of the surface of the sun is approximately

5700k

The astronomer who, at the turn of the century, measured the spectra of hundreds of thousands of stars, leaving a catalog that astronomers used for the rest of the century, was:

Annie Jump Canon

The element whose nucleus has two protons and two neutrons is

Helium

The most common element in the Sun is

Hydrogen

Which law do astronomers use to determine the masses of the stars in a spectroscopic binary system?

Kepler's third law

Which of the following types of star is the coolest (has the lowest surface temperature)?

M

The red supergiant phase occurs

Near the end of a high-mass star's life

Two stars have the same luminosity, but star B is three times farther away from us than star A. Compared to star A, star B will look

Nine times fainter

What does the Chandrasekhar limit describe?

The maximum size of a white dwarf

Some objects in space just don't have what it takes to be a star. Which of the following is a "failed star", an object with too little mass to qualify as a star?

a Brown dwarf

in the Sun, when an electron collides with its anti particle, they will produce

a gamma ray

According to the formula E=mc2

a little bit of mass can be converted into a substantial amount of energy

Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for

aurorea

Why are astronomers much more interested in the luminosity of a star than its apparent brightness?

because the luminosity tells us how bright a star really is, while apparent brightness only tells us how bright it happens to look from Earth

The layer of the Sun where hot material bubbles up from the bottom and then releases its heat to space at the top is called the

convective zone

Which part of the Sun's atmosphere is hottest?

corona

a star loses most mass

during the giant phase

Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?

fusing hydrogen into helium in their cores

The building up of heavier nuclei from lighter ones is called

fusion

The granulation pattern that astronomers have observed on the surface of the Sun tells us that

hot material must be rising from the Suns hotter interior

When an astronomer talks about the luminosity of the star she is studying, she is referring to

how much energy the star gives off every second

Where on the H-R diagram would most stars in our vicinity lie?

in the lower right, among the least luminous main sequence stars

The element with the most stable nuclei is

iron

Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different:

masses

What keeps a neutron star collapsing into a black hole

neutron degeneracy pressure

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

only on the right size and never on the left

The antimatter version of an electron is called a

positron

Which of the following is NOT one of the fundamental particles that we find inside atoms?

positrons

How do astronomers know that the age of the solar system is about 4.5 billion years old?

radioactive dating shows primitive meteorites have that age

An H-R Diagram plots the luminosity of stars against their

surface temperature

The radius of a white dwarf is about the size of

the Earth

the hottest zone of the Sun is

the core

As you go upward from the Sun's photosphere

the density decreases

When an astronomer measures a color index for a star, what is she measuring?

the difference between how bright a star looks at two different wavelength regions

Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call

the main sequence

Heat is

thermal energy in motion


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