Further Constraints on the Presence of a Debris Disk in the Multiplanet System Gliese 876

Abstract

Using both the Very Large Array (VLA) at 7mm wavelength, and the Australia Telescope Compact Array (ATCA) at 3mm, we have searched for microwave emission from from cool dust in the extrasolar planetary system Gliese 876 (Gl 876). Having detected no emission above our 3-sigma detection threshold of 135 microJy, we rule out any dust disk with either a mass greater than 0.0006 Earth masses or less than ~250 AU across. This result improves on previous detection aperture thresholds an order of magnitude greater, and it has some implications for the dynamical modeling of the system. It also is consistent with the Greaves et al. hypothesis that relates the presence of a debris disk to close-in planets. Due to the dust-planetesimal relationship, our null result may also provide a constraint on the population or composition of the dust and small bodies around this nearby M dwarf.