ASTR155-hw3-ch2

# ASTR155-hw3-ch2 - make the math go faster for you! 2....

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Astronomy 155: Formation and evolution of planetary systems Homework #3. Due in class on Monday, February 22, 2010. As always, feel free to research your topic by checking out journal articles and reputable websites like NASA, universities, SETI.org, etc. 1. What is the angular resolution that you would need (at a wavelength of 1 micron) to spatially resolve protoplanetary disks in the following star forming regions: a. TW Hydrae, d = 50 pc b. Ophiuchus, d = 120 pc c. Taurus, d = 150 pc d. Orion, d = 410 pc Compare your answers to the resolution of some modern observatories (Hubble, Keck, Spitzer, and one more that you choose yourself) at this wavelength. A spreadsheet will
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Unformatted text preview: make the math go faster for you! 2. Derive equation 2.3 on page 36, starting with the definition of the orbital velocity for circular orbits. (Hint: this is not a very elaborate derivation, should only be a few lines, and we sort of did it in class.) 3. Refer to the discussion about vertical structure (Chap. 2 section 2). Desch (2007) derived a new equation for the surface density of a disk, &quot; ( r ) = 343 r 10AU # \$ % &amp; ’ ( ) 2.168 g * cm-2 . Can this disk’s self-gravity still be neglected at 1 AU? 5 AU? 10 AU? Does the approximation (to neglect the disk’s self-gravity) get better or worse as you go further away from the star? Assume a 1 M sun star....
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## This note was uploaded on 09/08/2010 for the course ASTR 155 at San Jose State University .

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