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Multiple Choice Quiz


A star which is discovered to be a binary system on the basis of the Doppler shifts of the spectral lines of its two stars is called a
A)spectroscopic binary
B)astrometric binary
C)visual binary
D)eclipsing binary

A light curve is a plot showing
A)luminosity versus spectral type
B)brightness versus time
C)radial velocity versus magnitude
D)mass versus luminosity

Which type of binary star is revealed by periodic decreases in brightness?
A)spectroscopic binaries
B)eclipsing binaries
C)visual binaries
D)astrometric binaries

A visual binary system has an observed period of 10 years and a semi-major axis of 10 a.u. If one of the stars is exactly the same as the the sun (one solar mass), what is the mass of the other star?
A)0.9 solar masses
B)3 solar masses
C)9 solar masses
D)27 solar masses

What information about a binary star system is sufficient to make it possible to find the sum of the masses of the two stars?
A)orbital period and separation
B)distance and spectral type
C)age and temperature
D)chemical composition and absolute magnitude

What property of a star can almost never be determined unless it is a member of a binary star system?

Mass exchange in close binary systems can produce:
A)X-ray emission from an accretion disk
B)recurrent novae if one partner is a white dwarf
C)modification of the evolutionary status of both stars
D)all three answers

The explosive burning of hydrogen on the surface of a white dwarf produces a
D)splitting of the white dwarf into a binary system

When a black hole is part of a close binary star system, the system may be a strong source of x-rays. Where do the x-rays come from?
A)the companion star, which is heated by the black hole
B)a disk of hot matter around the black hole
C)from the black hole itself
D)from planets which are captured by the black hole

What kind of objects are thought to be identified with flickering x-ray sources?
A)binary star systems containing black holes
B)supernova remnants like the Crab Nebula
C)supergiant stars
D)main sequence stars on which flares occur

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