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New Constraints on Companions and Dust within a Few AU of Vega

Mennesson, B. and Serabyn, E. and Hanot, C. and Martin, S. R. and Liewer, K. and Mawet, D. (2011) New Constraints on Companions and Dust within a Few AU of Vega. Astrophysical Journal, 736 (1). Art. No. 14. ISSN 0004-637X. doi:10.1088/0004-637X/736/1/14.

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We report on high contrast near-infrared (~2.2 μm) observations of Vega obtained with the Palomar Fiber Nuller, a dual sub-aperture rotating coronagraph installed at the Palomar Hale telescope. The data show consistent astrophysical null depth measurements at the 10^(–3) level or below for three different baseline orientations spanning 60 deg in azimuth, with individual 1σ uncertainties ≤7 × 10^(–4). These high cancellation and accuracy levels translate into a dynamic range greater than 1000:1 inside the diffraction limit of the 5 m telescope beam. Such high contrast performance is unprecedented in the near-infrared and provides improved constraints on Vega's immediate ( 20 to 250 mas, or 0.15 to 2 AU) environment. In particular, our measurements rule out any potential companion in the [0.25-1 AU] region contributing more than 1% of the overall near-infrared stellar flux, with limits as low as 0.2% near 0.6 AU. These are the best upper limits established so far by direct detection for a companion to Vega in this inner region. We also conclude that any dust population contributing a significant (≥1%) near-infrared thermal excess can arise only within 0.2 AU of the star, and that it must consist of much smaller grains than in the solar zodiacal cloud. Dust emission from farther than 2 AU is also not ruled out by our observations, but would have to originate in strong scattering, pointing again to very small grains.

Item Type:Article
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Mennesson, B.0000-0003-4205-4800
Mawet, D.0000-0002-8895-4735
Additional Information:© 2011 The American Astronomical Society. Received 2011 March 7; Accepted 2011 April 20; Published 2011 June 29. Based on observations obtained at the Hale Telescope, Palomar Observatory as part of a continuing collaboration between the California Institute of Technology, NASA/JPL, and Cornell University. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The data presented are based on observations obtained at the Hale Telescope, Palomar Observatory, as part of a continuing collaboration between Caltech, NASA/JPL, and Cornell University. We thank the Palomar Observatory staff for their assistance in mounting the PFN and conducting the observations at the Hale telescope.
Funding AgencyGrant Number
Subject Keywords:circumstellar matter; instrumentation: high angular resolution; stars: individual (Vega)
Issue or Number:1
Record Number:CaltechAUTHORS:20150526-121554212
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Official Citation:New Constraints on Companions and Dust within a Few AU of Vega. B. Mennesson et al. 2011 ApJ 736 14
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57808
Deposited On:26 May 2015 20:29
Last Modified:10 Nov 2021 21:55

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