General Astrophysical Concepts: Astronomical length scales

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Transcript General Astrophysical Concepts: Astronomical length scales

Pop-quiz #5
Which of the following statements is FALSE?
A. Elliptical galaxies are classified E0 to E7 in order
of increasing ellipticity (i.e. increasing degree of
flattening)
B. An SBc spiral galaxy and an Sbc spiral galaxy have
different bulge-to-disk ratios
C. Irregular galaxies are a sub-class of disk galaxies
D. An SBd galaxy’s spiral arms are more tightly
wound (i.e. more closed) than an Sab galaxy’s
spiral arms
Pop-quiz #6
Two stars A and B have the same luminosity,
but B appears to be 4 times brighter than A.
Assuming there is no dust between us and the
stars, which of the following statements must be
TRUE?
A.
B.
C.
D.
Stars A and B have the same temperature
Star B is twice as large as star A
Star B is twice as far away as star A
Star A is twice as far away as star B
Pop-quiz #7
Which of the following statements is FALSE?
A.
B.
C.
D.
Black holes emit Hawking radiation which can be characterized
as black-body radiation with a temperature that is proportional
to the black hole’s mass
The event horizon or Schwarzschild radius of a black hole, the
region over which it is capable of trapping light (radiation), is
proportional to the black hole’s mass
“A black hole has no hair” is a statement that describes the loss
of identity of matter when it is swallowed by a black hole
The gravitational field of a black hole extends out to an infinite
distance
Pop-quiz #8
Which of the following statements is FALSE?
A.
B.
C.
D.
E.
Radio jets and lobes are powered by synchrotron radiation
produced by charged particles moving in a magnetic field
The typical mass of a super-massive black hole that powers the
nucleus of a quasar is about five million times the mass of our
Sun
The light-emitting region of a typical quasar is comparable in
size to our Solar System
Quasars and AGNs can be 100 to 1000 times more luminous
than our Milky Way galaxy
Most galaxies have massive black holes at their centers