Astronomy 201 Assignment #3
a) One of the simplest and most convincing arguments for common descent of all life on earth is
the study of gene sequences, more specifically: phylogenetic reconstruction. This method is used
to try and construct a phylogen
Astronomy Assignment #4
1) Blackbody Temperature of Mars:
a) Some of the earliest fossil cells depicted as unicells in spherical and fibrous growth forms,
were found by a team, led by Dr David Wacey of the University of Western Australia and
Astronomy Assignment #1
1) It takes about 8 minutes and 20 seconds for light to travel from the surface of of the Sun to
A light second:
A light hour:
A light year:
a) Since light takes time to travel we never actually see light in the curre
Consider a 100W light bulb. If you cup your hands around the bulb very close to it but not
touching it your hands will absorb 100W (100 Joules per second) of radiant energy1 . This is
called the luminosity of the bulb, i.e. L = 100 W.
3 THE LOCAL GROUP
The local group
The local group (LG) of galaxies is dominated by the bright spiral galaxies, the Milky Way and
The LG may be dened as all galactic systems bound gravitationally to the MW and M31.
This can be dicult t
2 A UNIVERSE OF GALAXIES
A Universe of galaxies
Stars exist in galaxies but galaxies are distributed throughout the Universe. Therefore, to understand questions such as the physical origins of galaxies, distances to galaxies and the ages of stars
A good working denition of a galaxy is a population of stars, gas and dust bound gravitationally
within a dark matter halo.
Set Christianson text as reading on the early history of galaxy studies and Hubbles conrmation
4 ELLIPTICAL GALAXIES
Inferring the density from the surface brightness
The surface brightness prole, which essentially traces the distribution of stars, can be used to infer
the underlying 3D matter density distribution.
ASTR 201 Assignment 2
1. You are analyzing Moon rocks that contain small amounts of uranium-238, which decays into
lead with a half-life of 4.5 billion years.
(a) In one rock from the lunar highlands, you determine that 55% of the original uranium-238
ASTR 201 Assignment 6
Due 12.30pm Friday 30th October.
1. Using the data in Appendix E.3 of the textbook (or taken from the web) determine if Enceladus
is in orbital resonance with any other major Saturnian moons? Note that if the ratio of orbital
ASTR 201 Assignment 1: Solutions
1. Given that the velocity of light is 3 108 ms1 , dene a light-second, a light-hour and a
light-year in metres. Express your answer scientic notation. How long does it take light to
travel from the surface of the Sun to t
ASTR 201 Assignment 5: Solutions
1. Sojourner was the rover component of the 1997 Mars Pathnder mission. Sojourner was
powered by a solar array with a battery backup. Calculate the maximum solar generated
electric power available to Sojourner. The followi
ASTR 201 Assignment 7: Solutions
1. Assume that the Milky Way Galaxy has 500 billion stars. Based on the statistics presented
in the textbooks and lecture, how many would be Sun-like G-stars? How many would be K
stars? How many would be M stars? If you as
ASTR 405 Assignment 2: Solutions
The marks for each question are indicated in parentheses. A total of 16 marks are available.
1. Derive an expression for the angular diameter distance as a function of redshift in an Einstein
de Sitter universe. The radi
4 BIG BANG NUCLEOSYNTHESIS
Big Bang Nucleosynthesis
The theory describing the creation of light elements in the universe is, together with the properties of the CMB, one of the physical cornerstones of the Hot Big Bang model of the un
ASTR 405 Assignment 5: Solutions
The marks for each question are indicated in parentheses. A total of 18 marks are available.
1. Consider a survey to detect quasars gravitationally lensed by foreground galaxies. The probability that a foreground galaxy
ASTR 405 Assignment 3: Solutions
Due 10am Thursday 6th February
The marks for each question are indicated in parentheses. A total of 23 marks are available.
1. What is the Sachs-Wolfe eect? In what way does it aect the observed properties of the
ASTR 405 Assignment 1: Solutions
The marks for each question are indicated in parentheses. A total of 20 marks are available.
1. Conduct a literature search to answer the following questions:
(a) What is the current expansion rate of the universe expres
ASTR 405 Assignment 4: Solutions
The marks for each question are indicated in parentheses. A total of 15 marks are available.
1. For each scenario described below compute the primordial abundance of Helium-4 assuming
that all available neutrons are conv
3 THE COSMIC MICROWAVE BACKGROUND
The Cosmic Microwave Background
The Cosmic Microwave Background (CMB) radiation is observed as an all sky radiation eld whose
peak emission occurs in the mmwavelength region of the electromagnetic spectrum (confusingl
2 MEASURING THE UNIVERSE
Measuring the universe
We have seen so far that the cosmological model is expressed is highly geometric terms, i.e. a
homogeneous and isotropic line element dened by a time varying scale factor and a spatial curvature
1 A MATHEMATICAL DESCRIPTION OF THE UNIVERSE
A mathematical description of the universe
The broad aim of cosmology is to build a mathematical model that describes the observed properties
of the universe. Furthermore, any model must change to accommoda
6 LARGESCALE STRUCTURE
The global properties of the universe geometry, chemistry and early density uctuations are well
described by GR, BBN and CMB respectively. The present day universe displays great complexity
ASTR 405 Midterm exam:
17th February 2011, 10.00am, CLE C214.
Allotted time: 75 minutes.
Answer all questions.
You are allowed a calculator and one formula sheet, hand written on one side of an 8.5x11 page.
You may assume throughout this exam that the H
5 DARK MATTER IN THE UNIVERSE
Dark Matter in the universe
Consideration of the geometry of the universe as described by General Relativity, combined with
the particle and thermal history of the universe outlined via BBN and CMB analys
The cosmological constant, parameterised as , has a history as long as relativistic cosmology
itself. The presence (or otherwise) of within cosmological models has always been motivated by
observations. As we shall see by the end of th
Due in class : 18 Sept 2013
As you do these problems, you will need to make some assumptions (e.g., wavelength of light) or look
up some parameters (e.g., distance to the Moon). State your assumptions and parameters for full
Due in class : 2 October 2013
State all assumptions and parameters in your answers for full credit.
1. He II is a H-like atom with Z=2. It has spectral lines at 420.0 and 468.6 nm.
Find the energy associated with each transitio