29:62 General Astronomy
Winter Semester 1999

Second Homework Set...Due February 10, 1997
Yah, I know it's the same day as the exam. Do it anyway!

Show calculations and give reasons for your answers. Don't go around confused and despondent; if you do not know how to get started, ask us for help. Nota Bene: To get the data necessary for some of these problems, you must refer to reference tables in the book or catalogs. Appendix 12 of the text is particularly useful.

1. A star with an absolute magnitude M = 0 is observed with an apparent magnitude m = 5.0. What is the distance of the star in parsecs?
2. The apparent magnitude limit of the Hubble Space Telescope (HST) is about +30. How far out in space could the HST see a star like Rigel?
3. How close would a red dwarf star have to be to be as bright as Betelgeuse?
4. In class I talked about the star Ursa Majoris ( UMa). From its spectrum we know it is identical to Vega. The apparent magnitude of UMa is 2.44. What is its distance?
5. Here's a fun one. A newly discovered element Otium has three bound states. The first is the ground state n =1. The first excited state (n=2) is 5 electron volts above the ground state. The second excited state (n=3) is 7 electron volts above the ground state. The continuum is 9 electron volts above the ground state, in other words an Otium atom hit with 9 electron volts of energy is ionized.
   (a) What is the wavelength of light emitted in a transition?
   (b) Assuming Otium is present in large amounts in stellar atmospheres, describe how the strength of the Otium line changes as the temperature of the star changes. Compare this behavior with that of the hydrogen lines.

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