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Searching for faint companions with VLTI/PIONIER. II. 92 main sequence stars from the Exozodi survey

Marion, L. and Absil, O. and Ertel, S. and Le Bouquin, J.-B. and Augereau, J.-C. and Blind, N. and Defrère, D. and Lebreton, J. and Milli, J. (2014) Searching for faint companions with VLTI/PIONIER. II. 92 main sequence stars from the Exozodi survey. Astronomy and Astrophysics, 570 . Art. No. A127. ISSN 0004-6361.

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Context. The Exozodi survey aims to determine the occurrence rate of bright exozodiacal discs around nearby main sequence stars using infrared interferometry. Although the Exozodi survey targets have been carefully selected to avoid the presence of binary stars, the results of this survey can still be biased by the presence of unidentified stellar companions. Aims. Using the PIONIER data set collected within the Exozodi survey in 2012, we aim to search for the signature of point-like companions around the Exozodi target stars. Methods. We make use of both the closure phases and squared visibilities collected by PIONIER to search for companions within the ~100 mas interferometric field of view. The presence of a companion is assessed by computing the goodness of fit to the data for a series of binary models with various separations and contrasts. Results. Five stellar companions are resolved for the first time around five A-type stars: HD 4150, HD 16555, HD 29388, HD 202730, and HD 224392 (although the companion to HD 16555 was independently resolved by speckle interferometry while we were carrying out the survey). In the most likely case of main sequence companions, their spectral types range from A5V to K4V. Three of these stars were already suspected to be binaries from Hipparcos astrometric measurements, although no information was available on the companions themselves so far. In addition to debiasing the statistics of the Exozodi survey, these results can also be used to revise the fraction of visual binaries among A-type stars, suggesting that an extra ~13% A-type stars are visual binaries in addition to the ones detected in previous direct imaging surveys. Conclusions. We estimate that about half the population of nearby A-type stars could be resolved as visual binaries using a combination of state-of-the-art interferometry and single-aperture imaging, and we suggest that a significant fraction of these binaries remains undetected to date.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Absil, O.0000-0002-4006-6237
Ertel, S.0000-0002-2314-7289
Defrère, D.0000-0003-3499-2506
Lebreton, J.0000-0003-1476-5963
Milli, J.0000-0001-9325-2511
Additional Information:© 2014 ESO. Article published by EDP Sciences. Received 8 August 2014. Accepted 6 September 2014. Published online 03 November 2014. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 089.C-0365 and 090.C-0526. The authors thank the French National Research Agency (ANR, contract ANR-2010 BLAN-0505-01, EXOZODI) for financial support. L.M. acknowledges the F.R.S.-FNRS for financial support through a FRIA PhD fellowship. We thank S. Borgniet and A.-M. Lagrange for helpful discussions on HD 224392 and on radial velocity surveys of early-type stars. This work made use of the Smithsonian/NASA Astrophysics Data System (ADS) and of the Centre de Données astronomiques de Strasbourg (CDS).
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR-2010 BLAN-0505-01
Subject Keywords:binaries: close, circumstellar matter, techniques: interferometric
Record Number:CaltechAUTHORS:20141208-100759097
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Official Citation:Searching for faint companions with VLTI/PIONIER - II. 92 main sequence stars from the Exozodi survey L. Marion, O. Absil, S. Ertel, J.-B. Le Bouquin, J.-C. Augereau, N. Blind, D. Defrère, J. Lebreton and J. Milli A&A 570 A127 (2014) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52462
Deposited By: Ruth Sustaita
Deposited On:08 Dec 2014 18:48
Last Modified:11 Oct 2019 01:37

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