What

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Whats the Deal with Low-Mass Stars, Brown
Dwarfs, and Planets?

• Kelle Cruz
• American Museum of Natural History

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People Care About Planets
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Low-Mass Stars, BDs, Jupiter

• All about same size as Jupiter
• L dwarfs can be either a stellar or sub-stellar.
• Both planets and brown dwarfs cool over time
• Jupiter was a T dwarf in youth

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Definition of Planet

• In the Solar System (low mass)
• Sphericity
• Pluto Diameter
• Only 9
• Discard altogether
• Terrestrials, Jovians, etc.

• Outside the Solar System (high mass)
• Orbits another body
• Formed in circumstellar disk rather than grav.
  collapse
• Difficult to observe
• Deuterium Burning
• 13 MJupiter cutoff

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Kuiper Belt Objects

• Xena (2003 UB313)
• Larger than Pluto (10th Planet?)
• Has a moon

From Mike Browns website.

• 2003 EL61
• Has two moons
• 2005 FY9
• Both very bright and ¾ Plutos size.

From Mike Browns website.
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GQ Lup B

• Primary
• T Tauri (young Sun)
• Secondary (Planet)
• Spectral type M9-L4
• Mass 1-42 MJupiter

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2M 1207B

• Primary
• young (8 Myr), active
• brown dwarf (M8)
• Secondary
• 5 MJupiter, L5-L9.5
• Too wide and too massive to have formed in a
  circumstellar disk.

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In Closing

• What the heck is a planet?
• None of the proposed definitions take care of
  both mass ends at the same time.
• Personally, I think time will tell but in the
  meantime, enjoy the spectacle!
• Provides a great way to engage the public
• Signifies an exciting time in astronomy.