Post Internal Symposium Party

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Post Internal Symposium Party Wednesday, Feb.
28th, 6pm 105 N. Camino Miramonte (6th/Country
Club)
- Talk about the symposium! - Form new
collaborations! - Enjoy food! And beer!
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Could we detect rocky planets from the ground?

• Phil Hinz

Roger Angel John Codona Matt Kenworthy Ari
Heinze Suresh Sivanandam
Michael Meyer
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Why search from the ground?

• Space is preferable but the Terrestrial Planet
  Finder Program is currently unfunded.
• Ground-based system is amenable to
  experimentation.

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The Main Issues

• Prevalence of Rocky Planets ( How many stars will
  we need to search?)
• Contrast versus Separation
• Background Noise and Performance

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Planet Finding in the Thermal-IR

• MMT L' survey by Heinze et al.

fake 10 Jupiter mass planet at 20 AU
1 arcsec
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Planet Detection Capabilities
1 hour 5 sigma limits

• Detect 5-10 MJ planets
• 100-300 zody warm debris disks
• Detect 1-3 MJ planets
• 3-10 zody warm debris disks
• Detect lt1 MJ planets
• 3-10 zody warm debris disks

• 3.8 um 25 uJy 10 um 750 uJy
• 3 ?/D 0.48 3 ?/D 1.0
• 3.8 um 7 uJy 10 um 200 uJy
• 3 ?/D 0.37 3 ?/D 0.77
• 3 ?/b 0.21 3 ?/b 0.44
• 3.8 um 0.6 uJy 10 um 18 uJy
• 3 ?/D 0.12 3 ?/D 0.25

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Could we detect rocky planets?

• Not as hopeless as you might guess in
  extrapolating from gas giant limits.
• We would be looking for planets in equilibrium
  with their star rather than self-luminous gas
  giant planets.

Possible Scenarios

• Earth-like planets are common (1-3 per system).
• More massive rocky planets may be detectable.
• Hotter Earth-size planets may be detectable.
• We could see young Earths in systems just forming
  or after a moon-like impact.

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How common are rocky planets?

• Microlensing
• Gould et al. detect a 13 Earth Mass planet at 2.7
  AU
• Beaulieau et al. detect a 5.5 ME planet at 2.6 AU
• Radial velocities
• GJ 876 d is 7.5 ME (Rivera et al. 2005)
• 55 Cnc e is 14 ME
  (2.6 RE if rocky)
• mu Arae c is 15 ME (Udry et al. 2006)
• Detections have been made despite a strong
  selection bias against lower mass.

• Gould et al. claim the two microlensing
  detections indicate that the fraction of stars
  with planets in the sensitive separation range is
  32 with a lower limit (90 confidence) of 16.

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Expected Rocky Planet Flux
For d3 pc and R2 R_e the flux is 20 uJy. The
contrast is 10 million (17.5 magnitudes) for such
a detection. We would expect to detect such a
planet in 1 hour with the GMT. Stars in the
sample should be the brightest nearby stars.
Tinetti, Meadows, Crisp, Fong, Velusamy, Snively
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The Stellar Sample for a detection at 10 microns
Consider a planet detectable if it is outside 3
?/D (0.25) and above a photometric limit of 10
uJy Earth mass planets could be detectable
around two stars with GMT planets with ME10
(2 RE) would have 4x flux. These could be
detectable around 4 stars planets with ME30 (3
RE) would have 9x flux. These could be detectable
around 7 stars
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The Stellar Sample for a detection at 4 microns
Consider a planet detectable if it is outside 3
?/D (0.1) and above the photometric limit of
0.5 uJy A hot Earth (600 K) could be detectable
around 7 stars with GMT The hot Earth would
need to have a clear atmosphere at 3.8 um!
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Summary

• Microlensing, radial velocity and Kepler will
  improve our knowledge of how common rocky planets
  may be in the next several years.
• If common, GMT could study rocky planets around
  the very nearest stars and probe their
  atmospheres in the thermal infrared.
• The key technologies are an adaptive secondary
  and some form of high contrast imaging (phase
  plate, PIAA)

GMT secondary as seen from the instrument