Brown Dwarfs and Extrasolar Planets

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Brown DwarfsandExtrasolar Planets

• Zoë Ames
• AST 225

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Formation of Brown Dwarfs
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Brown Dwarfs

• Peak temperature 2600 K
• Have masses less than .084 Msun
• Usually between 10Mjupiter and 84 Mjupiter
• Luminosity 10-5 Lsun
• Absolute magnitude 17

4
Brown Dwarf IMF

• Measured mass function down to 0.03 Msun 5.97 x
  1028 kg
• In a study of 280 GKM stars in our neighborhood,
  only found 1 BD

• 16 of sun like stars have companions larger
  than Jupiter
• 11 have other stars,
• 5 have planets
• lt1 have BD

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Dwarf Numbers

• Mass kg 1.45E29
• Msun 7.27E-02
• Number 1.24E12
• Density /pc3 0.577
• T- sec 1.45E18
• T-year 4.59E10

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Extrasolar Planets

• Definition of planet according to IAU
• Orbits the sun
• round shape
• cleared the neighborhood
• Mass gt Pluto lt 13 Mjupiter
• Assuming each star has a Jupiter
• Planets 9.45 x107 Msun .94 mass of stars

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Detecting Planets
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Detecting MACHOs

• Massive Astrophysical Compact Halo Objects
• Microlensing object in foreground causes
  distant object to be doubled, distorted,
  magnified

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MACHOs

• If the mass in the halo were entirely made up of
  masses around 0.4 Msun, it is expected that 39
  microlensing events would happen only 1 was
  measured
• Msun around 0.01 8 of mass in halo
• Msun 0.5 to 1 20

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Planet Numbers

• Mass kg 1.88E27
• Msun 9.45E-04
• Number 9.53E13
• Density /pc3 44.42313
• T- sec 1.88E16
• T-year 5.96E08

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Sources

• Webpages
• http//astro.berkeley.edu/stars/bdwarfs/
• http//exoplanet.eu/pictures.html
• http//exoplanets.org/
• http//planetquest.jpl.nasa.gov/index.cfm
• http//user.bahnhof.se/davidgr/browndwf/bd_home.h
  tml
• http//www.astro.caltech.edu/ftod/tres/tres.html
• http//www.extrasolar.net/
• http//www.hao.ucar.edu/public/research/stare/sear
  ch.html
• Books
• Astrophysics of Brown Dwarfs Proceedings of a
  Workshop Held at George Mason University. 1986.
• Clark, Stuart G. Extrasolar Planets the Search
  for New Worlds. 1998.
• Goldsmith, Donald. Worlds Unnumbered The
  Search for Extrasolar Planets. 1997.
• International Astronomical Union. Brown Dwarfs
  Proceedings of the 211th Symposium of the
  International Astronomical Union. 2003.
• Kepner, Terry L. Extrasolar Planets A Catalog
  of Discoveries in Other Star Systems. 2005.
• Reid, I. Neill. New Light on Dark Stars Red
  Dwarfs, Low-Mass Stars, Brown Dwarfs. 2005.
• Villard, Ray. Infinite worlds An Illustrated
  Voyage to Planets Beyond our Sun. 2005.
• Articles
• Grether, Daniel Et all. How Dry is the Brown
  Dwarf Desert? Quantifying the Relative Number of
  Planets, Browns Dwarfs and Stellar Companions
  Around Nearby Sun-like Stars. 2006.