Further deep imaging of HR 7329 A (eta Tel A) and its brown dwarf companion B

Abstract

About 4" south of the young A0-type star HR 7329, a faint companion candidate was found by Lowrance et al. (2000). Its spectral type of M7-8 is consistent with a young brown dwarf companion. Here, we report ten new astrometric imaging observations of the pair HR 7329 A and B, obtained with the Hubble Space Telescope and the Very Large Telescope, aimed at showing common proper motion with high significance and possible orbital motion of B around A. With 11 yrs of epoch difference between the first and our last image, we can reject by more than 21 sigma that B would be a non-moving background object unrelated to A. We detect no change in position angle and small or no change in separation (2.91 +/- 2.41 mas/yr), so that the orbit of HR 7329 B around A is inclined and/or eccentric and/or the orbital motion is currently only in radial direction. If HR 7329 B is responsible for the outer radius of the debris disk around HR 7329 A being 24 AU, and if HR 7329 B currently is at its apastron at 200 AU (4.2" at 47.7 pc), we determine its pericenter distance to be 71 AU, its semi-major axis to be 136 AU, and its eccentricity to be e=0.47. From the magnitude differences between HR 7329 A and B and the 2MASS magnitudes for the HR 7329 A+B system, we can estimate the magnitudes of HR 7329 B (J=12.06+/-0.19, H=11.75+/-0.10, Ks=11.6+/-0.1, L=11.1+/-0.2 mag) and then, with a few otherwise known parameters, its luminosity and mass (20-50 Jupiter masses). In the deepest images available, we did not detect any additional companion candidates up to <=9", but determine upper limits in the planetary mass regime.

7 pages, 3 figures, accepted for publication in MNRAS

References in corpus (12)

• A giant planet imaged in the disk of the young star Beta Pictoris
• Search for Associations Containing Young stars (SACY): I. Sample & Searching Method
• A catalogue of young runaway Hipparcos stars within 3kpc from the Sun
• Nearby debris disk systems with high fractional luminosity reconsidered
• The Gemini NICI Planet-Finding Campaign: Discovery of a Close Substellar Companion to the Young Debris Disk Star PZ Tel
• Discovery of an 86 AU Radius Debris Ring Around HD 181327
• New Neighbors: Parallaxes of 18 nearby stars selected from the LSPM-north catalog
• Resolved debris disk emission around eta Tel: a young Solar System or ongoing planet formation?
• A search for new members of the beta Pic, Tuc-Hor and epsilon Cha moving groups in the RAVE database
• Astrometric and photometric monitoring of GQ Lup and its sub-stellar companion
• Direct detection of a substellar companion to the young nearby star PZ Telescopii
• Mid-infrared imaging of brown dwarfs in binary systems

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