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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). GJ 876 The Planetary System Next Door. GJ 876 M4V d= 4.7 pc GJ 876b M=1.89 M Jup , P=60 days
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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)
GJ 876The Planetary System Next Door GJ 876 M4V d= 4.7 pc GJ 876b M=1.89 MJup, P=60 days GJ 876c M=0.57 MJup, P=30 days GJ876d M= 7.5 MEarth, P=1.9 days One of only 3 of about 130 M dwarfs searched that has planets and only one with giant planets
Debris Disks • Dust has short lifetime (few Myrs), so detection means presence of larger bodies (10’s 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)
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
No Detection M < 0.00064 MEarth (3σ limit) within about 5 AU (one beam). Comparisons (Greaves et al. 2004) εEridani M ~ 0.016 MEarth τCeti M ~ 0.0005 MEarth