ASTR 103 Assignment 4
1. Instruments on board balloons and on spacecraft can detect photons which have
energy 511 keV (511 103 eV). What is the wavelength of these photons. To what
part of the electromagnetic spectrum do these photons belong?
ASTR 103 Assignment 1
1. The diameter of the Sun is 1.4 1011 cm, and the distance to the nearest star, Proxima
Centauri, 4.2 ly. Suppose you want to build a scale model of the Sun and Proxima
Centauri, and you are using a ball 30 cm in diameter
ASTR 103 Assignment 2
1. Suppose you traveled to a planet with 4 times the mass of the Earth, and 4 times the
diameter of the Earth. Would you weigh more or less on that planet than on Earth? By
what factor will your weight change?
ASTR 103 Assignment 3
1. Stars A and B are both equally bright as seen from the Earth, but A is 120 pc away
while B is 24 pc away. Which star has the greater luminosity? How many times
greater is it?
The inverse square law relating bri
ASTR 103 Assignment 6
1. To convert one kilogram of hydrogen (1H) into Helium (4He) in the proton-proton
cycle, you must start with 1.5 kg of hydrogen. Explain why, and explain what
happens to the other 0.5 kg.
The proton-proton cycle
ASTR 103 Assignment 5
1. The bright star Zubeneschmali ( Librae) is of spectral type B8 and has a luminosity
of 130 L. What is the stars approximate surface temperature? How does its radius
compare to that of the Sun?
By referring to t
ASTR 103 Assignment 11
1. In the binary system of two neutron stars discovered by Hulse and Taylor, one of the
neutron stars is a pulsar. The distance between the stars varied between 1.1 and 4.8
times the radius of the Sun. The time interval be
ASTR 103 Assignment 10
1. The Crab nebula has an apparent size of about 5 arcmin, and this size is increasing at
a rate of 0.23 arcsec per year. (a) Assume that the expansion rate has been constant
over the entire history of the Crab Nebula. Und
ASTR 103 Assignment 7
1. (a) Find the ratio of the energy flux from a patch of a sunspots penumbra to the
energy flux from an equally large patch of undisturbed photosphere. Which patch is
brighter? (b) Find the ratio of the energy flux from a p
ASTR 103 Assignment 9
1. The Ring Nebula is a planetary nebular in the constellation Lyra. It has an angular
size of 1.4 arcmin 1.0 arcmin and is expanding at the rate of about 20 km/s.
Approximately how long ago did the central star shed its ou
ASTR 103 Assignment 8
1. As a red giant, the Suns luminosity will be about 2000 times greater than it is now,
so the amount of solar energy falling on the Earths surface will increase to 2000
times its present day value. Hence, to maintain therm