Astronomy 100 - Problem Set 8
Due: Thursday 8 May 2008
Name:
Fill in the box with the correct answer (answers should be just a few
words or a number).
-
The Sun travels in a circular orbit at
a velocity of 220 km/second at a distance of 8.5 kiloparsecs from the
center of the Galaxy (note that these numbers are slightly different
from those in your book). Calculate the number of years it takes the
Sun to complete an orbit (i.e., the circumference of a circle with an
8.5 kiloparsec radius) around the center of the Galaxy.
(There are 3.1 x 1013 kilometers/parsec and 3.2 x 107
seconds/year.)
-
What type of galaxy are the Large and Small Magellanic clouds (which
are satellites of our own Milky Way)?
-
The Large Magellanic Cloud is a small galaxy that orbits around our galaxy.
It is observed to be at a distance of 50 kiloparsecs and moving at a speed
of 150 kilometers/second. What is the mass contained within the radius of
the orbit of the Large Magellanic Cloud and, therefore, a lower limit to
the mass of our Galaxy?
- If Hubble's Constant is 70 km/s/Mpc (70 kilometers/s of
recession for every Megaparsec (million parsecs) of distance from us).
How far away is a galaxy cluster which has a recessional
velocity of 14,000 km/s?
- The hydrogen Balmer line Hb has a wavelength of 486.1 nm in the
laboratory.
It is observed in a quasar at 1944.4 nm, what is the red shift of this quasar?
-
If the space telescope proved that Hubble's constant is actually twice as large
as it is currently believed to be, the implied age of the universe would be
how many times the currently accepted value?
-
If the average density of the universe is less than
the ``critical density'' is the universe ``open'' or ``closed''?
-
What is the fate of such a universe?
-
One second after the Big Bang the universe was at a temperature of one hundred
million degrees Kelvin. Today the temperature of the universe is approximately