Physics 134 Homework Set 7 Solutions
1. The star Aldebaran, in Taurus, has a surface temperature of 3934 K. (a) What is Aldebaran's wavelength of maximum emission? What color would you expect it to be? We use Wien's displacement law max T = 0.0028977685 m
Physics 134 Homework Set 1 Solutions
1. Here are some applications of the small-angle formula. It is actually a useful tool to carry around, astronomy aside. (a) The Duke Chapel tower stands 210 ft. tall. How far from the tower would you have to stand in
Physics 134 Homework Set 5 Solutions
1. In the last HW you computed Saturn's radius. Let's follow that calculation up to see what else we can learn using what we now know. (a) Saturn's moon Janus orbits the planet in an orbit that, at opposition, subtend
Physics 134 Homework Set 4 Solutions Due 2/6/12
1. We observe that oppositions of Saturn repeat every 378 days. (a) Use this information to find the sidereal period of Saturn, in (Earth) years. You may take a year to mean 365.25 days and neglect the disti
Physics 134 Homework Set 3 Solutions
1. (a) About how many more sidereal days are there in a year than solar days (tropical or sidereal year is immaterial here)? At the level of accuracy expected here we can assume a year of 365 (solar) days. A sidereal d
Physics 134 Homework Set 2 Solutions
1. Describe how you would go about finding the star Mirfak which lies in the constelation Perseus at Decl. 49 52m ; R.A. 3h 24m in the sky in Durham on February 3 at 8 pm. Try to estimate the Azimuth and Altitude at wh
Physics 134 Homework Set 6 Due 2/20/13
1. Let's try to find the Roche limit, the distance from a planet at which a moon would be broken apart by tidal forces. We will make a few simplifying assumptions along the way, and at one point I will help you with
Physics 134 Homework Set 12 Due 4/17/13
1. The star Cephei varies in brightness with a period of 5.4 days. Its spectrum contains plenty of heavy element lines, showing it is a Population I Cepheid variable (in fact, the name derives from this star). On av
Physics 134 Homework Set 11 Due 4/10/13
1. Kapteyn's star has a parallax angle of 0.255 arcseconds. (a) What is the distance to Kepteyn's star in pc? Distance and parallax angle are related by 206265" D = , 1 AU p or D 1" = , 1 pc p so that distance to Ka
Physics 134 Homework Set 10 Solutions
1. Assume that the Sun formed 4.5 billion years ago with an essentially uniform composition (in the early Sun convection destroyed chemical differentiation). The star was initially 73% Hydrogen and 27% Helium (by mass
Physics 134 Homework Set 8 Solutions
1. In class, we computed the surface temperature of Earth, assuming it was in equilibrium with Solar radiation and noting the importance of the atmospheric greenhouse effect. In this problem we will use the same kind o
Physics 134 Homework Set 9 Solutions
1. We estimated the temperature at which a cloud becomes unstable to gravitational collapse to be given by kB T
GM m R0
where M is the total mass of the cloud, R0 its
size, and m the mass of a typical particle. For a
Physics 134 Homework Set 13 Solutions
1. Muons, as you may recall from our discussion in class, are negatively charged leptons with a mass somewhat larger than that of an electron. The masses of elementary particles are often given in terms of their energ
Physics 134 Quiz 2 Solutions 2/13/13
1. As we mentioned, there was a total lunar eclipse on Dec. 21, 2010. (a) About what time did the Moon rise on Dec. 21? Lunar eclipses happen during full Moon, which means the Moon rose around sunset. Since December 2
Physics 134 Quiz 2 2/13/13
1. As we mentioned, there was a total lunar eclipse on Dec. 21, 2010. (a) About what time did the Moon rise on Dec. 21? (b) A partial Solar eclipse (visible in Europe and Africa) occurred soon after this. When would you predict
Physics 134 Quiz 1 1/24/12
Imagine that the Earth suddenly reversed the direction in which it spins, rotating from East to West at the same rate at which it now spins West to East. Answer the following questions on how Astronomy would change: 1. The appar
Physics 134 Quiz 1 Solutions 1/24/12
Imagine that the Earth suddenly reversed the direction in which it spins, rotating from East to West at the same rate at which it now spins West to East. Answer the following questions on how Astronomy would change: 1.
Physics 134 Midterm Exam Solutions 3/7/13
In solving the exam problems you may use any material associated to the class. It is essential that you show your work: putting down some number with no explanation will result in no credit even if the number is c
Physics 134 Midterm Exam 3/7/13
In solving the exam problems you may use any material associated to the class. It is essential that you show your work: putting down some number with no explanation will result in no credit even if the number is correct. Be
Physics 134 Quiz 3 4/3/13
Briefly answer 3 of the following questions. 2-3 sentences should suffice where the answer is not a calculation.
1. The Cassini Division is the large gap between the A and B rings of Saturn. The inner edge of the Division (called
Physics 134 Quiz 3 4/3/13
Briefly answer 3 of the following questions. 2-3 sentences should suffice where the answer is not a calculation.
1. The Cassini Division is the large gap between the A and B rings of Saturn. The inner edge of the Division (called
Physics 55 Midterm Exam Solutions 2/27/12
Answer the following questions (4 pts each) 1. The star Castor in Gemini has celestial coordinates approximately R.A. = 7h 34m 36s , Decl. +31 53m 18s . Viewed from Durham, Castor's maximal altitude above the hori
Physics 55 Midterm Exam 2/27/12
Answer the following questions (4 pts each) 1. The star Castor in Gemini has celestial coordinates approximately R.A. = 7h 34m 36s , Decl. +31 53m 18s . Viewed from Durham, Castor's maximal altitude above the horizon is abo
Physics 55 Midterm Exam 4/10/12
1. Centauri has a parallax angle of 0.75 arc-seconds. (a) [5pt] Find the distance to Centauri. (b) [5pt] The apparent brightness of Centauri is approximately 2.07 10-11 that of the Sun. Find the luminosity of Centauri. (c)
Physics 55 Midterm Exam 4/10/12
1. Centauri has a parallax angle of 0.75 arc-seconds. (a) [5pt] Find the distance to Centauri. Distance in pc is related to parallax angle by D = 1/p = (0.75)-1 = 1.33 pc . (b) [5pt] The apparent brightness of Centauri is a
Physics 55 Final Exam 4/30/12
General Instructions The rules are the same ones that have applied to all of our exams. You may use your notes, the text, lecture slides, and any course material. You may not go online to find answers, nor use Starry Night or
Physics 55 Final Exam 4/30/12
General Instructions The rules are the same ones that have applied to all of our exams. You may use your notes, the text, lecture slides, and any course material. You may not go online to find answers, nor use Starry Night or