Astronomy Exam 3
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
