Orbital Constraints on the beta Pic Inner Planet Candidate with Keck Adaptive Optics

Abstract

A point source observed 8 AU in projection from beta Pictoris in L' (3.8 micron) imaging in 2003 has been recently presented as a planet candidate. Here we show the results of L'-band adaptive optics imaging obtained at Keck Observatory in 2008. We do not detect beta Pic b beyond a limiting radius of 0.29 arcsec, or 5.5 AU in projection, from the star. If beta Pic b is an orbiting planet, then it has moved >=0.12 arcsec (2.4 AU in projection) closer to the star in the five years separating the two epochs of observation. We examine the range of orbital parameters consistent with the observations, including likely bounds from the locations of previously inferred planetesimal belts. We find a family of low-eccentricity orbits with semimajor axes ~8-9 AU that are completely allowed, as well as a broad region of orbits with e<~0.2, a>~10 AU that are allowed if the apparent motion of the planet was towards the star in 2003. We compare this allowed space with predictions of the planetary orbital elements from the literature. Additionally, we show how similar observations in the next several years can further constrain the space of allowed orbits. Non-detections of the source through 2013 will exclude the interpretation of the candidate as a planet orbiting between the 6.4 and 16 AU planetesimal belts.

6 pages, 4 figures, pdflatex, ApJL accepted

References in corpus (5)

• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
• Confidence Level and Sensitivity Limits in High Contrast Imaging
• Planets of Beta Pictoris revisited
• VLT/NACO coronagraphic observations of fine structures in the disk of beta Pictoris
• Is Beta Pic b the transiting planet of November 1981?

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• A 5 Micron Image of beta Pictoris b at a Sub-Jupiter Projected Separation: Evidence for a Misalignment Between the Planet and the Inner, Warped Disk
• The Lowest Mass Member of the beta Pictoris Moving Group
• Spin-orbit alignment of the $\beta$ Pictoris planetary system
• Independent confirmation of β Pictoris b imaging with NICI