Astr 2020 Problems in Stellar Astronomy
Homework Set 1 Solution
Chapter 1 # 41, 42, 45, 49 & 53
1.41. Convert the following numbers to scientific notation:
a) 7,000,000,000
b) 0.00346
c) 1,238
a) 7,000,000,000 = 7.0x109
b) 0.00346 = 3.46x10-3
c) 1,238 = 1

Astr 2020 Problems in Stellar Astronomy
Homework Set 7 Solutions
Chapter 14 # 47 & 48 + Supplemental Problems
14.47. The Sun shines by converting mass into energy according to Einsteins wellknown relationship E = mc2. Show that if the Sun produces 3.85x10

Astr 2010 Problems in Stellar Astronomy
Homework Set 2 Solutions
Chapter 2 # 43 & 45 + Supplemental Problems
2.43. The Moons orbit is tilted by 5 relative to Earths orbit around the Sun. What is the
highest altitude in the sky that the Moon can reach, as

Astr 2020 Problems in Stellar Astronomy
Homework Set 5 Solutions
Chapter 13 # 45, 48, 49 & 50
13.45. Sirius, the brightest star in the sky, has a parallax of 0.379 arcseconds. What is
the distance in parsecs? In lightyears?
d (parsec)
1
(arcsec)
1
2.64

Constants and Numbers
11
1km = 1000m
1 AU = 1.496 X 10 m
1 ly = 9.46x1015 m
1 ly = 63240 AU
1 pc = 3.26156 ly
1 eV = 1.6 x 10-19 J
1 hour = 3600 sec
1 day = 86400 sec
1 year = 3.156x107 sec
G = 6.67 X 10 11 N m2 / kg2
c = 3.0 X 108 m/s
T(K) = T(C) + 273.1

Constants and Numbers
1km = 1000m
1 AU = 1.496 X 1011 m
1 hour = 3600 sec
1 day = 86400 sec
11
2
2
N m / kg
c = 3.0 X 108 m/s
G = 6.67 X 10
1ly = 9.46x1015 m
1 year = 3.156x107 sec
M sun 1.99 10 30 kg
M Moon 7.35 10 22 kg
M Earth 5.97 10 24 kg
GST for 0 h

Astr 2020 Problems in Stellar Astronomy
Homework Set 3 Solutions
Supplemental Problems
Supplemental Problem 1 . The star 55 Cancri has been discovered to have several
planets orbiting it. The innermost planet orbits the star in 2.817 days with a semimajor

Astr 2020 Problems in Stellar Astronomy
Homework Set 4 Solutions
6.45. The resolution of the human eye is about 1.5 arcminutes. What would the aperture
of a radio telescope (observing at 21 cm) have to be to have this resolution? Even
though the atmospher

Astr 2020 Problems in Stellar Astronomy
Homework Set 6 Solutions
Supplemental Problems
Supplemental Problem 1. What is the luminosity of a 4.0 solar mass main sequence
star? A 9.0 solar mass main sequence star? A 0.75 solar mass main sequence star?
L M 3.