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70 Cards in this Set

  • Front
  • Back
The light we receive from the Sun comes from the layer of the Sun's atmosphere called the
The wavelength peak of the Sun's radiation is in the middle of the
visible spectrum
About 94 percent of the nuclei in the outer parts of the Sun are
Magnetic storms on the Earth are caused by
solar flares
As the solar atmosphere expands outward into interplanetary space it becomes the
The dark region of a sunspot is often surrounded by a less dark region called the
Dark lines threading their way across the Sun, visible in Ha light near sunspots are
The orientation of the Sun's magnetic field changes, repeating a full cycle every
22 years
The temperature of the Sun's photosphere is about
6000 K
The prominent absorption lines in the optical solar spectrum are called ___________ lines.
Both b and c
When a solid body is heated the result is a(n)
continuous spectrum
Categories of stars based on their respective spectra are called
spectral types
Our Sun is of spectral type
What two things determine the apparent magnitude of a star?
intrinsic brightness, distance from the observer
The angle at which a star appears to move when observed from the ends of a baseline of I A.U. is the star's
The magnitude a star would have if it were at a standard distance of 10 parsecs is its
absolute magnitude
A star that is 40 parsecs from the Sun would, if moved to a distance of 10 parsecs, be
16 times brighter
A temperature-luminosity diagram of stars usually includes a diagonal band called the
main sequence
The angular rate of the change of position of a star in the sky is its
proper motion
The size of a single star can be determined if we know its absolute magnitude and its
A star which appears double when observed directly, and is held together by mutual gravitation is called a(n)
visual binary
A binary star which varies in brightness as one component passes in front of the other is a(n)
eclipsing binary
The main value in the study of binary stars is the ability it gives us to determine stellar
Common red giant variable stars such as Mira that vary slowly in brightness are called
long-period variables
The period-luminosity relation applies to
Cepheid variables
Star clusters with irregular shapes, and containing relatively young stars, are called
open clusters
Star clusters made of many thousands of older stars are called
globular clusters
The age of an open cluster can be determined from its
temperature-luminosity diagram
All RR Lyrae stars have the same ___________ magnitude.
absolute magnitude
The least massive stars are about ___________ percent as massive as the Sun.
One class of low-mass, erratically variable pre-main-sequence stars is called
T Tauri stars
The particles in the following list that are not a part of the structure of an atom are
When an atom loses an electron, it becomes a(n)
The number of protons in nucleus of an atom of 146C is
If normal carbon is 126C, the number of electrons in singly-ionized carbon will be
The neutral particle with little or no mass that is given off during nuclear reactions is called a(n)
The process of building heavier atoms from lighter ones is called
In a main-sequence star, the gravitational forces are balanced by
thermal pressure.
The nuclei of atoms are held together by
strong force.
Compared with low-mass stars, high-mass stars have main-sequence lifetimes that are
Stars retaining less than 1.4 solar masses after their unstable phase will become
white dwarfs
Planetary nebulae are called that because
they appear similar to planets when observed in a small telescope.
As a white dwarf ages it will
A very massive star at the end of its main sequence life becomes a
red supergiant
When the core of a massive star collapses, rebounds, and explodes into a supernova, it picks up much of its energy from the outflow of
No supernovae have been seen in our Milky Way Galaxy since
The progenitor of Supernova 1987A was a(n)
blue supergiant.
The final proof of the nature of pulsars came from observations of the
Crab Nebula.
Although they were first expected to be extremely stable and constant, it was discovered that pulsars
gradually slow down.
Gravitational waves were first directly detected using Earth-based detectors in
Gravitational waves have not yet been detected.
While studying the distribution of globular clusters, Harlow Shapley discovered that we are not in the
center of the Galaxy.
The "spiral arms" of the Galaxy are embedded in the
The mechanism that may have created the spiral arms of our Galaxy by piling up material to create new stars is called the
density wave.
Stars in the galactic halo are generally
very old.
In which of the following parts of the electromagnetic spectrum are we learning the least about the very center of our Galaxy?
visible light
To trace out the spiral structure of our Galaxy we should look at
very young objects.
The symbol H II would denote a hydrogen atom with a charge of
Because molecular hydrogen is difficult to detect, astronomers map the distribution of molecular material in our Galaxy with observations of the more easily detectable molecule
A heavily-studied giant molecular cloud is in
Which of the following has not been detected in interstellar space?center of the Galaxy.
Classification of spiral galaxies into subtypes is based on
how tightly wound the spiral arms are.
The type of galaxy with typically the most dust and gas is
If enough mass is present in a small enough volume at the center of a galaxy, it implies the presence of
a black hole.
The largest nearby cluster of galaxies is the
Virgo cluster.
A cluster of galaxy clusters is called a
If a galaxy is moving away from us at 7100 km/sec, it must be (assuming Ho= 71 km/s/Mpc) at a distance of
100 Mpc.
The length of time light from a galaxy has been traveling through space in order to reach us is the galaxy's
lookback time.
A spectral line at 1000 Å is seen at what wavelength when its redshift is 5?
6000 Å
Which of the following are primary distance indicators?
Cepheid variables
The fact that circular velocity does not decrease at galactic radii greater than that of the Sun indicates that our Galaxy
is more massive than previously believed.