A) electrons dropping between energy levels n = 3 and n = 2 in hydrogen atoms
B) electrons dropping between energy levels n = 2 and n = 1 in hydrogen atoms
C) thermal blackbody radiation emitted by the hot gas
D) scattering of starlight from dust grains in the nebula
Correct Answer
verified
Correct Answer
verified
A) hydrogen and carbon
B) hydrogen and oxygen
C) hydrogen and helium
D) nitrogen and oxygen
Correct Answer
verified
Correct Answer
verified
A) sphere of gas after collapse from an interstellar cloud but before nuclear reactions have begun
B) small interstellar cloud before it collapses to become a star
C) star near the end of its life before it explodes as a supernova
D) shell of gas left behind from the explosion of a star as a supernova
Correct Answer
verified
Correct Answer
verified
A) mass of about 1000 solar masses in volume with a diameter of about 1000 ly
B) mass of about 1 million solar masses in volume with a diameter of about 100 ly
C) mass of about 1 million solar masses in volume with a diameter of about 100 au, about the size of the solar system
D) mass of about 1000 solar masses in volume with a diameter of about 100 ly
Correct Answer
verified
Correct Answer
verified
A) giant molecular clouds.
B) globular clusters.
C) blue reflection nebulae.
D) hot, turbulent gas thrown out in a supernova explosion.
Correct Answer
verified
Correct Answer
verified
A) thermonuclear reactions begin so suddenly in stars of less than 0.08 solar mass that the star is disrupted by an explosion.
B) protostars of less than 0.08 solar mass cannot form.
C) protostars of less than 0.08 solar mass are not massive enough to contract.
D) the temperature in a contracting protostar of less than 0.08 solar mass does not become high enough for nuclear reactions in normal hydrogen to start.
Correct Answer
verified
Correct Answer
verified
A) main-sequence phase
B) protostar phase
C) horizontal-branch phase
D) as the star moves up the red giant branch for the first time
Correct Answer
verified
Correct Answer
verified
A) the H-R diagram (spectroscopic parallax)
B) the distance-magnitude relationship
C) the Stefan-Boltzmann relationship
D) parallax
Correct Answer
verified
Correct Answer
verified
A) mainly white dwarf stars and dying stars but no faint red stars, red giants, or bright blue stars
B) mostly blue giants and supergiants and a few red giant stars, white dwarfs, and dim red stars
C) many red giants, white dwarfs, and dim red stars
D) stars along the entire main sequence from bright blue to dim red, with no bright red giant stars but significant amounts of dust and gas
Correct Answer
verified
Correct Answer
verified
A) The electrons generate a very large pressure to oppose further compression.
B) The electrons fall into orbit around one another in mutual pairs that reduce the restricted quantum space, allowing further shrinkage of the star.
C) Nuclear fusion occurs between electrons, producing energy and heating the star's core.
D) Half the electrons are transformed into antimatter (positrons) , which then annihilates electrons, producing a burst of energy and the explosion of the star.
Correct Answer
verified
Correct Answer
verified
A) Type II Cepheids are older, having evolved from Type I Cepheids.
B) The two types have different metallicities.
C) Type I Cepheids are members of binary systems, whereas Type II Cepheids are solitary stars.
D) Type II Cepheids have gone through the helium flash, whereas Type I Cepheids have yet to do so.
Correct Answer
verified
Correct Answer
verified
A) The star begins to expand and become a red giant.
B) Convection begins in its interior.
C) The star stops accreting mass from the interstellar cloud.
D) Nuclear reactions begin in its core.
Correct Answer
verified
Correct Answer
verified
A) protostars
B) T Tauri stars
C) RR Lyrae variables
D) Cepheid variables
Correct Answer
verified
Correct Answer
verified
A) prevents high-mass stars from forming in low-mass interstellar clouds.
B) sets a limit to the crowding together of electrons in any given small volume of space.
C) limits the number of atoms that can become ionized in a star.
D) prevents two stars of the same spectral class from occupying the same binary star system.
Correct Answer
verified
Correct Answer
verified
A) Plot the stars on a Hertzsprung-Russell diagram, and see which stars are still on the main sequence.
B) Measure the motions of the stars in the cluster, and compare the measurements with theoretical models.
C) Measure the heavy element abundance for the stars in the cluster.
D) Count the number of T Tauri stars in the cluster.
Correct Answer
verified
Correct Answer
verified
A) in clumps, concentrated in interstellar clouds
B) concentrated in narrow riverlike streams of gas that circle the Galaxy
C) uniformly distributed through space
D) concentrated around existing stars because of the stars' gravitational pull
Correct Answer
verified
Correct Answer
verified
A) Type II Cepheids are dwarf stars and thus much less luminous than Type II giants.
B) Type I Cepheids are metal-rich and thus have more heavy elements in their atmospheres.
C) Type II Cepheids are metal-rich and thus have more heavy elements in their atmospheres.
D) Type I Cepheids get their energy primarily from hydrogen fusion while Type II Cepheids get their energy primarily from helium fusion.
Correct Answer
verified
Correct Answer
verified
A) detached binary
B) semidetached binary
C) contact binary
D) overcontact binary
Correct Answer
verified
Correct Answer
verified
A) Cepheid variables
B) Population II
C) horizontal-branch stars
D) Population I
Correct Answer
verified
Correct Answer
verified
A) 40,000 solar masses
B) 1 million solar masses
C) 1.5 million solar masses
D) 1.96 million solar masses
Correct Answer
verified
Correct Answer
verified
Showing 41 - 60 of 325
Related Exams