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49 Cards in this Set
- Front
- Back
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All globular clusters in our Milky Way galaxy are about how old? |
about ten billion years old |
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What two things are needed to create an emission nebula? |
Hot stars and interstellar gas, particularly hydrogen. |
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At what core temperature does hydrogen begin to fuse to helium? |
10 million k |
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Which statement is true about interstellar mediums? |
We know more about the gas than the dust. |
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Which statement is true about dark dust clouds? |
They can be penetrated only with longer wavelengths such as radio and infrared. |
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Complex molecules in the interstellar medium are found... |
Primarily in the dense dust clouds |
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What happens to light passing through even thin clouds of dust? |
It dims and reddens the light of all more distant stars. |
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The density of interstellar dust is very low, yet it still blocks light because... |
The dust particles are about the same size as the light waves they absorb. |
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What is the primary visible colour of an emission nebula? |
Red, due to the Ha line of hydrogen. |
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Emission nebulae like M42 occur only near stars that emit large amounts of... |
Ultraviolet radiation. |
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(T/F) 21cm radio waves are emitted by all molecular hydrogen. |
False. |
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Some regions along the plane of the Milky Way appear dark because... |
Stars in that region are hidden by dark dust particles. |
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What are the characteristics of an open cluster of stars? |
A few hundred, mostly main-sequence stars. |
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A cloud fragment too small to collapse into a main sequence star becomes a... |
Brown dwarf. |
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What information does 21cm radiation provide about the gas clouds? |
All of the above. (density, motion, distribution, and temperature) |
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Why are star clusters ideal "laboratories " for stellar evolution? |
Their stars are all about the same age, composition and distance from us. |
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During the T-tauri phase of a protostar, it... |
May develop very strong wind. |
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Which statement about stages of star birth is false? |
Nuclear reaction begin at the core by stage 4. |
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On an HR diagram, a protostar would be... |
Above and to the right of the main sequence. |
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The single most important determinant of the temperature, density, radius, luminosity, and pace of evolution of a protostar is its... |
Mass. |
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Approximately how many Brown dwarfs are believed to exist in the Milky Way Galaxy? |
One Hundred Billion. |
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When an electron in a hydrogen atom changes its spin from same to opposite direction as the proton, it... |
Emits a radio wave photon. |
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The spectra of interstellar gas clouds shows that they have the same basic composition as... |
Stars. |
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(T/F) Young open clusters contain a lot of hot young blue-white stars. |
True. |
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The most common molecule in a molecular cloud is... |
Molecular Hydrogen, H2. |
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A 20 solar mass star will stay on the main sequence for 10 million years, yet its iron core can exist for only a... |
Day. |
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A cluster with a lot type O and B stars, but no bright K or M stars, is very... |
Young. |
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A recurrent nova could eventually build up to a... |
Type 1 supernova |
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If light from a distant star passes close to a massive body, the light beam will... |
Bend towards the star due to gravity. |
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(T/F) Both space and time are warped near the strong gravitational fields of neutron stars and black holes. |
True. |
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Which are the two most popular candidates for gamma ray bursters? |
Hypernova making a black hole, and merger of two neutron stars. |
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An object more massive than the sun, but roughly the same size of a city, is a... |
Neutron star. |
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A method for identifying a black hole is to... |
Look for its effects on a nearby companion. |
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What can we detect from matter that has crossed the event horizon? |
Nothing. |
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What would happen if more mass was added to a 1.4 solar mass neutron star? |
It would blow off mass as an x-ray burster. |
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Most pulsars have a measured mass of... |
About 1.4 solar masses. |
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Two-thirds of all known millisecond pulsars are found in what type of object? |
Globular clusters. |
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The densely packed neutrons of a neutron star cannot balance the inward pull of gravity if the total mass is... |
Greater than Schwartzchilds limit of 3 solar masses. |
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(T/F) Because of their immense size, black holes moving through space consume huge quantities of interstellar matter along their paths. |
False. (Black holes do not move) |
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The largest known black holes... |
Lie in the core of most massive galaxies. |
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A hypernova creates... |
A black hole. |
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The supernova of 1054 AD produced... |
A pulsar with a period of 33 milliseconds, visible optically. |
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If the sun were replaced with one solar mass black hole, ... |
We would still orbit it in a period of one year. |
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Who discovered the first 4 pulsars? |
Jocelyn Bell. |
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What statement about gamma ray bursters is NOT correct? |
They are scaled up x-ray bursters, with more massive objects involved. |
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Which of these does NOT exist? |
A 1.5 solar mass white dwarf. |
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(T/F) Einstein's prediction of the curvature of space was confirmed by the 1919 total solar eclipse. |
True. |
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Three terrestrial-sized planets in orbits of a fraction of an AU have been found near... |
a millisecond pulsar. |
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Which of these is NOT an argument for Cygnus X-1 being a black hole? |
The mass of the visible star is greater than that of the x-ray source. |
