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Study of debris disk around GJ 876 to trace parent bodies and infer presence of planets. Observations using ATCA and VLA show no detection of dust within 5 AU.
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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