Question

1/ Sirius A has a luminosity of 9.98 x 10^27 W and a surface temperature of about 9400K. What is its radius?

A/ r = 7.56 x 10^8 m

B/ r = 1.34 x 10^9 m

C/ r= 1.26 x 10^13 m

D/ r = 7.94 x 10^-14 m

3/ which of the following stellar properties is the most fundamental to a star’s main-sequence and post-main sequence life?

A/ temperature

B/ mass

C/ luminosity

D/ radius

4/ Stars Moppit and Boppit orbit each other as members of a binary star system. Their period of rotation about their combined centre of mass is 10 years. The semi-major axis of Boppit’s orbit around the centre of mass is 15.25 AU. What is the combined mass of Moppit and Boppit?

A/ Mmoppit + Mboppit = 2.24 x 10^31 kg

B/ Mmoppit + Mboppit = 1.36 x 10^15 kg

C/ Mmoppit + Mboppit = 9.83 x 10^18 kg

D/ Mmoppit + Mboppit = 7.04 x 10^31 kg

5/ What are the 3 major types of galaxies?

A/ Elliptical galaxies, spiral galaxies and spiral galaxies

B/ Elliptical galaxies, spheroidal galaxies and spiral galaxies

C/ Spiral galaxies, dwarf galaxies, and main-sequence galaxies

D/ Elliptical galaxies, irregular galaxies, and disk galaxies

6/ Which of the following galaxies is most likely to be classified as an irregular galaxy

A/ a galaxy full of young stars which does not seem to have a spherical or disk-like shape

B/ a galaxy with a bar in the center, and weak hints of spiral arms in a great disk

C/ a galaxy with a small bulge but prominent spiral arms

D/ a small, spherical galaxy made of old stars

7/ which of the following types of galaxies contain old stars?

A/ elliptical galaxies

B/ spiral galaxies

C/ lenticular galaxies

D/ barred spiral galaxies

E/ both A and C

F/ both B and D

G/ all A,B,C,D

H/ None of A,B,C,D

8/ Which of these galaxies is most likely to be actively forming stars?

A/ a bulge galaxy

B/ a dwarf galaxy

C/ a spiral galaxy

D/ an elliptical galaxy

9/ the 2011 Nobel Prize in Physics was awarded to 3 men who study white dwarf supernova explosions, which are known as Type la supernovae. The following problem is designed to give you a feel for what they did, and the sorts of apparent brightnesses and distances they were working with. A typical Type la supernova explosion has a luminosity of 1.72 x 10^36 W. If we observe such a supernova to have an apparent brightness of 1.25 x 10^-17 W/m^2, how far away in meters is it?

A/ 2.76 x 10^21 m

B/ 2.99 x 10^-26 m

C/ 3.31 x 10^25 m

D/ 2.05 x 10^26 m

10/ what does Hubble’s Law state?

A/ the more distant a galaxy, the greater the speed with which it moves away from us

B/ closer galaxies seem to be moving away from us faster than more distant galaxies

C/ the more distant a galaxy, the greater the speed with which is moving toward us

D/ the universe is accelerating in its expansion

11/ imagine that you have obtained spectra for several galaxies and have measured the redshift of each one to determine its speed away from us. Here are your results:

Galaxy 1: recession velocity is 15000 km/s

Galaxy 2: recession velocity is 20000 km/s

Galaxy 3: recession velocity is 25000 km/s

Estimate the distance to each galaxy from Hubble’s Law. Assume that H0 = 22km/s/Mlyr

A/ The distances are as follows:

Galaxy 1: 0.00147 Mlyr

Galaxy 2: 0.000110 Mlyr

Galaxy 3: 0.00088 Mlyr

B/ The distances are as follows:

Galaxy 1: 1.02 x 10^7 Mlyr

Galaxy 2: 1.82 x 10^7 Mlyr

Galaxy 3: 2.84 x 10^7 Mlyr

C/ The distances are as follows:

Galaxy 1: 31 Mlyr

Galaxy 2: 41 Mlyr

Galaxy 3: 52 Mlyr

D/ The distances are as follows:

Galaxy 1: 682 Mlyr

Galaxy 2: 909 Mlyr

Galaxy 3: 1136 Mlyr

12/ what may have happened to end the GUT era?

A/ the release of an enormous amount of energy, which may have caused inflation

B/ the annihilation of all antiprotons and almost all protons

C/ Gravity became distinct from the GUT force

D/ Hydrogen fusion reactions ceased

13/ What happens when a proton collides with an antiproton?

A/ they “annihilate” and convert into 2 protons

B/ they fuse together

C/ they repel each other

D/ they start to orbit each other

14/ what is the cosmic microwave background?

A/ it is the period of rapid expansion early in the universe’s history

B/ it is the wallpaper which covers the universe

C/ it is the left-over radiation from the Big Bang

D/ it is the left-over radiation from the first generation of stars

15/ what type of spectrum does the cosmic microwave background have?

A/ an absorption line spectrum

B/ an emission line spectrum

C/ a blackbody radiation spectrum

D/ a power law spectrum

16/ what 3 shortcomings of the Big Bang Model does the Inflation Hypothesis help to solve?

A/

1. Its inability to explain what happened at the end of the GUT Era

2. Its inability to explain what happened during the Electroweak Era

3. Its inability to explain why our universe should be observed to have an energy density equal to the critical energy density

B/

1. Its inability to explain the origin of the large-scale structure of matter

2. Its inability to explain the large-scale uniformity of the universe

3. Its inability to explain where hydrogen and other heavy elements made in the early universe come from

C/

1. Its inability to explain what happened during the Planck Era

2. Its inability to explain why there should have been more particles than antiparticles at the end of the Particle Era

3. Its inability to explain where the CMB comes from

D/

1. Its inability to explain the origin of the large-scale structure of matter

2. Its inability to explain the large-scale uniformity of the universe

3. Its inability to explain why our universe should be observed to have an energy density equal to the critical energy density

Answer 1