-
All G-type stars have approximately the same
temperature
-
**Most methods for determining the distances to stars which are too far away for the use of the trigonometric parallax method are based on
comparison of a star's apparent magnitude with an estimate of its absolute magnitude
-
**Which of the following definitely does not agree with present theories of stellar evolution?
[the misconception that] the more massive stars have the longest main sequence lifetimes.
-
What is Cygnus X-1?
a leading candidate for being a black hole
-
The Doppler effect enables us to measure the ____ of a star.
radial velocity
-
Which star has the longest main-sequence life expectancy?
[smallest number]
-
how to find relative magnitude of stars
Logarithmic scale of 2.51, starting from sixth magnitude and going down
-
**Which two ingredients are needed to make an emission nebula?
Hot stars and interstellar gas
-
What is the likely final fate of a star whose mass is 1.1 solar masses after it has finished its main sequence life?
It will shrink and become a white dwarf
-
What is the singularity that is often mentioned when talking about a black hole?
A point of infinite density
-
A mass of material is condensing into a star. If this "protostar" contains one half the mass of the Sun, when it finally contracts to the main sequence stage it will most likely be of which spectral type?
K
-
When the light of a star is dimmed by the effects of intervening dust, we are likely to __________ the distance to the star.
overestimate
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**The absolute magnitude of a star is defined to be the apparent magnitude that the star would have if it were at a standard distance of __ parsec(s).
10
-
The “helium flash” occurs at what stage of stellar evolution?
Low mass stars as they become red giants
-
Because of precession on the Earth, the
celestial poles gradually change position among the stars.
-
10,000 parsecs = ___ light years
32,600 light years
-
If considerable interstellar material was located between the observer and the star, how would the determined distance be affected?
The distance determination would be overestimated.
-
**Which kind of process, as a net result, supplies the energy for the stars?
Hydrogen is converted to helium through fusion.
-
The Crab nebula is material blown off a ____(1)____, which was observed by the Chinese in AD 1054. At its center we now observe a ____(2)____.
-
Which spectral types are the hottest?
O and B
-
Which spectral types are the coolest?
K and M
-
Which spectral type has the strongest hydrogen lines?
A
-
Which spectral type has the strongest molecular bands?
M
-
Which spectral types are red?
Cool stars - so K and M
-
Which of these is not a possible final stage of stellar evolution?
T Tauri stage
-
**Name the second most abundant element in typical stars.
Helium
-
**Observation of the shift of a star’s spectrum toward the red or blue enables us to determine the star’s
radial velocity
-
What characteristic is the same for all stars in a star cluster?
age
-
Which kind of star has the greatest average density?
Neutron star
-
Which of these features is NOT characteristic of nuclear fusion?
Very large, radioactive nuclei are produced as waste products.
-
The early experiments designed to search for solar neutrinos showed
probable difficulty in our theories of stellar interiors.
-
**Suppose you are at the equator, which has a latitude of 0°. The altitude of the north celestial pole as seen from your position is
- 0°
- The altitude of the north celestial pole is always the same as your latitude on the surface of the Earth.
-
Which is NOT a characteristic of a red giant?
Iron being formed into heavier elements
-
Stars at the left-hand end of the main sequence have which one of these?
Large masses
-
A good way to determine the distance of a distant star cluster is to
**compare its H-R diagram with a standard H-R diagram.
-
**Which of these is the greatest distance?
anything with parsecs
-
**Most methods for determining the distances to stars which are too far away for the use of the trigonometric parallax method are based on ________.
comparing a star's apparent magnitude and estimated absolute magnitude.
-
What effect does dust have on visible light passing through it?
It dims and reddens it.
-
The center of our galaxy is located in the direction of the constellation of
Orion.
-
What is the 21-cm line?
A radio wave produced by neutral hydrogen
-
Which clusters are generally located near the plane of the Milky Way?
Open clusters
-
The chief cause of the differences observed among the various types of stellar spectra is the result of differences in ______ from star to star.
surface temperature
-
The fact that the Sun is far removed from the center of our galaxy was first conclusively demonstrated by a study of the distribution in space of
globular clusters.
-
Which of the following is almost never found in our galaxy's halo?
Emission nebulae
-
The Magellanic clouds seen in the southern hemisphere are classic examples of
Irregular galaxies.
-
The Hubble Law allows astronomers to estimate the age of the Universe. Currently, the best estimate for this age from the Hubble Law and the Hubble Constant is about
14 years
-
When describing galactic structure, 21-cm radiation refers to
A radio wave produced by neutral hydrogen
-
What does the Hubble Law measure?
The rate of expansion of the Universe
-
**The distances to the nearer galaxies like M31 in Andromeda are based primarily on observations of the periods of the in these nearer galaxies.
Cepheid variable stars
-
Provo, Utah, is at 40° north latitude. How often is the Sun directly overhead at noon in Provo?
never
-
Which clusters are generally located in the halo of the Milky Way?
Globular
-
Recent data from distant supernovae indicate that
the expansion of the Universe is speeding up.
-
**What does the Hubble Law measure?
The rate of expansion of the Universe
-
Which of the following distance measurement methods (which do not include the Hubble relation) extends furthest into the cosmos?
Observations of type Ia supernovae
-
What do we believe to be the central engine for an active galaxy?
A supermassive black hole
-
A quasar is thought to be
a very luminous active galaxy at a very large distance from our galaxy.
-
The most distant objects that we can observe appear to be
quasars
-
The distance to the bright quasar 3C 273 is estimated to be about
2 billion light-years
-
At the present time, the value of the Hubble constant is
thought to have a value very close to 70 km/s/Mpc.
-
**Recent data from distant supernovae indicate that
the expansion of the Universe is speeding up.
-
In cosmology, the phrase “critical density” refers to the
density needed to produce precisely flat space.
-
In high-energy physics, when two gamma-ray photons meet, they can
disappear, creating a particle-antiparticle pair.
-
In cosmology, what is the “inflationary epoch”?
A short period of extremely rapid expansion when the Universe was very young
-
One wavelength that would be appropriate to monitor in SETI research would be
21 cm.
-
The “water hole,” a region of the radio spectrum chosen for searches for signals from intelligent life because galactic and Earth-based noise and atmospheric absorption are at a minimum, is so named because
two astronomically important wavelengths, the 21-cm line of H and a line from the hydroxyl radical OH, are in this region (the letters H and OH signifying water).
-
Isotropy and homogeneity, taken as assumptions regarding the structure and evolution of the Universe, are known as
the Cosmological Principle.
-
The spectrum of the cosmic microwave background shows a constant and nearly isotropic blackbody temperature of
2.7 K.
-
The Drake equation attempts to predict the
number of technologically advanced civilizations in our Galaxy.
-
Which elements were created during the Big Bang?
Hydrogen, helium, lithium, and beryllium
-
Which object is most likely to host planets supporting life as we know it?
Low-mass main sequence stars
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