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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
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Photosphere
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The wavelength peak of the Sun's radiation is in the middle of the
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visible spectrum
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About 94 percent of the nuclei in the outer parts of the Sun are
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hydrogen
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Magnetic storms on the Earth are caused by
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solar flares
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As the solar atmosphere expands outward into interplanetary space it becomes the
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corona
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The dark region of a sunspot is often surrounded by a less dark region called the
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penumbra
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Dark lines threading their way across the Sun, visible in Ha light near sunspots are
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filament
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The orientation of the Sun's magnetic field changes, repeating a full cycle every
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22 years
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The temperature of the Sun's photosphere is about
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6000 K
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The prominent absorption lines in the optical solar spectrum are called ___________ lines.
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Both b and c
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When a solid body is heated the result is a(n)
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continuous spectrum
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Categories of stars based on their respective spectra are called
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spectral types
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Our Sun is of spectral type
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G2
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What two things determine the apparent magnitude of a star?
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intrinsic brightness, distance from the observer
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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
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parallax
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The magnitude a star would have if it were at a standard distance of 10 parsecs is its
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absolute magnitude
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A star that is 40 parsecs from the Sun would, if moved to a distance of 10 parsecs, be
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16 times brighter
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A temperature-luminosity diagram of stars usually includes a diagonal band called the
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main sequence
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The angular rate of the change of position of a star in the sky is its
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proper motion
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The size of a single star can be determined if we know its absolute magnitude and its
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temperature
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A star which appears double when observed directly, and is held together by mutual gravitation is called a(n)
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visual binary
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A binary star which varies in brightness as one component passes in front of the other is a(n)
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eclipsing binary
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The main value in the study of binary stars is the ability it gives us to determine stellar
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masses
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Common red giant variable stars such as Mira that vary slowly in brightness are called
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long-period variables
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The period-luminosity relation applies to
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Cepheid variables
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Star clusters with irregular shapes, and containing relatively young stars, are called
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open clusters
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Star clusters made of many thousands of older stars are called
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globular clusters
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The age of an open cluster can be determined from its
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temperature-luminosity diagram
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All RR Lyrae stars have the same ___________ magnitude.
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absolute magnitude
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The least massive stars are about ___________ percent as massive as the Sun.
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8
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One class of low-mass, erratically variable pre-main-sequence stars is called
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T Tauri stars
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The particles in the following list that are not a part of the structure of an atom are
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photons
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When an atom loses an electron, it becomes a(n)
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ion
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The number of protons in nucleus of an atom of 146C is
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6
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If normal carbon is 126C, the number of electrons in singly-ionized carbon will be
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5
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The neutral particle with little or no mass that is given off during nuclear reactions is called a(n)
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neutrino
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The process of building heavier atoms from lighter ones is called
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nucleosynthesis
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In a main-sequence star, the gravitational forces are balanced by
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thermal pressure.
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The nuclei of atoms are held together by
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strong force.
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Compared with low-mass stars, high-mass stars have main-sequence lifetimes that are
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shorter
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Stars retaining less than 1.4 solar masses after their unstable phase will become
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white dwarfs
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Planetary nebulae are called that because
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they appear similar to planets when observed in a small telescope.
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As a white dwarf ages it will
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cool
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A very massive star at the end of its main sequence life becomes a
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red supergiant
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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
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neutrinos
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No supernovae have been seen in our Milky Way Galaxy since
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1604
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The progenitor of Supernova 1987A was a(n)
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blue supergiant.
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The final proof of the nature of pulsars came from observations of the
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Crab Nebula.
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Although they were first expected to be extremely stable and constant, it was discovered that pulsars
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gradually slow down.
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Gravitational waves were first directly detected using Earth-based detectors in
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Gravitational waves have not yet been detected.
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While studying the distribution of globular clusters, Harlow Shapley discovered that we are not in the
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center of the Galaxy.
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The "spiral arms" of the Galaxy are embedded in the
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disk
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The mechanism that may have created the spiral arms of our Galaxy by piling up material to create new stars is called the
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density wave.
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Stars in the galactic halo are generally
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very old.
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In which of the following parts of the electromagnetic spectrum are we learning the least about the very center of our Galaxy?
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visible light
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To trace out the spiral structure of our Galaxy we should look at
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very young objects.
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The symbol H II would denote a hydrogen atom with a charge of
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+1.
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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
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CO
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A heavily-studied giant molecular cloud is in
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Orion
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Which of the following has not been detected in interstellar space?center of the Galaxy.
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DNA
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Classification of spiral galaxies into subtypes is based on
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how tightly wound the spiral arms are.
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The type of galaxy with typically the most dust and gas is
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irregular
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If enough mass is present in a small enough volume at the center of a galaxy, it implies the presence of
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a black hole.
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The largest nearby cluster of galaxies is the
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Virgo cluster.
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A cluster of galaxy clusters is called a
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supercluster
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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
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100 Mpc.
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The length of time light from a galaxy has been traveling through space in order to reach us is the galaxy's
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lookback time.
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A spectral line at 1000 Å is seen at what wavelength when its redshift is 5?
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6000 Å
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Which of the following are primary distance indicators?
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Cepheid variables
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The fact that circular velocity does not decrease at galactic radii greater than that of the Sun indicates that our Galaxy
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is more massive than previously believed.
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