Solution to Exercise 1

1. From the electromagnetic spectrum:

Spectrum of Electromagnetic Radiation
Region Wavelength
(Angstroms)
Wavelength
(centimeters)
Frequency
(Hz)
Energy
(eV)
Radio > 109 > 10 < 3 x 109 < 10-5
Microwave 109 - 106 10 - 0.01 3 x 109 - 3 x 1012 10-5 - 0.01
Infrared 106 - 7000 0.01 - 7 x 10-5 3 x 1012 - 4.3 x 1014 0.01 - 2
Visible 7000 - 4000 7 x 10-5 - 4 x 10-5 4.3 x 1014 - 7.5 x 1014 2 - 3
Ultraviolet 4000 - 10 4 x 10-5 - 10-7 7.5 x 1014 - 3 x 1017 3 - 103
X-Rays 10 - 0.1 10-7 - 10-9 3 x 1017 - 3 x 1019 103 - 105
Gamma Rays < 0.1 < 10-9 > 3 x 1019 > 105

X-rays have wavelengths of approximately 0.1 to 10 Angstroms. From the Wien Law Applet, this corresponds to blackbody temperatures of approximately ? - ? K. (Note: Wien applet needs to be modified to go to higher temp. Also, is the formula displayed in the correct units in the applet?)

2. Most stars late in their lives will expand to become giant or supergiant stars because of events that take place in their interiors when then begin to exhaust their nuclear fuel. In a close binary, this can cause the star to overflow its Roche lobe, leading to accretion onto the companion.