Search%20for%20a%20Debris%20Disk%20Around%20GJ%20876

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Search for a Debris Disk Around GJ 876

• Paul Shankland (USNO, JCU) David Blank (JCU)
• Dave Boboltz (USNO) Joe Lazio (NRL)
• Graeme White (JCU)

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GJ 876The Planetary System Next Door

• GJ 876 M4V d 4.7 pc
• GJ 876b M1.89 MJup, P60 days
• GJ 876c M0.57 MJup, P30 days
• GJ 876d M 7.5 MEarth, P1.9 days
• One of only 3 of about 130 M dwarfs searched
  that has planets and only one with giant planets

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Debris Disks

• Dust has short lifetime (few Myrs), so detection
  means presence of larger bodies (10s of km in
  size)
• Dust is produced from collisions of such bodies
• Dust traces distribution of parent bodies
• Sometimes can infer presence of planets
• (e.g. epsilon Eridani)

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ATCA and VLA Observations

• Date Freq. Config. Time
  Srms
• GHz
  hrs mJy/Beam
• ATCA 9/05 94 H168 2.5
  1.1
• VLA 11/05 43 D
  3.4 0.04

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No Detection

• M lt 0.00064 MEarth (3s limit) within about 5
  AU (one beam).
• Comparisons (Greaves et al. 2004)
• e Eridani M 0.016 MEarth
• t Ceti M 0.0005 MEarth