HW2_Light - (assuming both stars are the same size)? b....

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ASTR302 Homework #2 (due in class on Wednesday, January 30, 2008) 1) Complete the Lecture Tutorial on Telescopes and Earth’s Atmosphere (pp 49-51). 2) Complete the Lecture Tutorial on Light and Atoms (pp 63-67). 3) Consider a hydrogen atom in the second excited state (n=3). Include an energy diagram with your solution to each of the following scenarios. a. If the excited atom returns to the ground state, what is the wavelength of the photon given off by the atom? b. What is the wavelength of a photon that would just barely ionize the hydrogen atom in the excited state (n=3), assuming all of the photon energy is transferred to the atom? 4) Assume that you are comparing two stars that are the same size. a. How much more energy is emitted by a star at 20,000K than one at 5000K
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Unformatted text preview: (assuming both stars are the same size)? b. What is the predominant color of each star in part (a)? Use the Wien displacement law and express your answers in wavelengths. 5) At what wavelengths will the following spectral lines be observed: a. A line emitted at 500 nm by a star moving towards us at 100 km/s b. A radio line with a rest frequency of 1420.4 MHz emitted by a cloud of neutral hydrogen moving away at 200 km/s. 6) Estimate the line width for a calcium line at 393.3 nm and for a hydrogen line at 410.1 nm for the following three cases: a. A star at 3,000K. b. A star at 6,000K. c. A star at 12,000 K. d. Describe and explain the relationships of temperature and mass with line width ....
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