1) A given object will form a black hole if its radius is less than its
Schwarzshild radius. This leads to a very peculiar feature of black holes
the more massive they are, the less dense the materia
1) Suppose a malevolent intelligence is trying to deceive us into thinking that a
binary system of the kind described last week exists, when in fact that isnt
the case. Suppose this evil being lives o
1) How big a shift in the wavelength of green light will this
instrument be able to detect?
7
We know (from class) that the wavelength of green light is 5000 A (= 5 10
m).
So, if the Doppler precision
1) There is a relativistic
expression for the addition of
velocities (that is, for the total
observed velocity vtot of
something that moves at
velocit
y
v1
with
respect
to
another object that itself
m
1) Read the homework policy (linked from the syllabus). Then answer
the following true/false questions:
a) You can drop your lowest homework score.
False
b) You can work on homework with other student
1) Suppose you observe a Sun-like star with a planet in an Earth-like
orbit. How massive does the planet have to be for it to be detected by the
Rocky Planet Finder?
Earth-like orbit:
a = 1AU
a3 = P 2
1) Consider a binary star system consisting of two 1.5M
8
neutron
stars. Sup- pose one of the neutron stars is a pulsar with an
average observed pulse period of exactly 2 seconds. If the
orbit is circ
1) The formula for the relativistic Doppler shift is
/
/0 =
1 + vR
/c 1
vR/c
1/2
1.
Show that the post-Newtonian approximation reproduces the result we
used before, namely that /0 = vR/c. What happe
1) a) Faint brown-dwarf stars have absolute magnitudes of around
17.5. How many times fainter than the Sun are these stars?
MBD = 17.5
Msun = 5
log
17.5 5 =
b1
5
12.52
5
b1
b2
5 = log b1
105 = b1
So b
1) a) Suppose the entire diff
between Hubbles measurement of the
Hubble constant and the currently known value of 70 km/s/Mpc was
due to observing the wrong kind of Cepheid. What is the diff
in
absolu