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

Abstract

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. Using the PIONIER data set collected within the Exozodi survey, we aim to search for the signature of point-like companions around the Exozodi target stars. We use 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. 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. 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.

arXiv commentAccepted for publication in A&A

References in corpus (21)

• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Stellar Multiplicity
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• Debris Disk Evolution Around A Stars
• The VAST Survey - III. The multiplicity of A-type stars within 75 pc
• PIONIER: a 4-telescope visitor instrument at VLTI
• From binaries to multiples II: hierarchical multiplicity of F and G dwarfs
• Speckle interferometry at SOAR in 2012 and 2013
• The VAST Survey - I. Companions and the unexpected X-ray detection of B6-A7 stars
• From binaries to multiples I: Data on F and G dwarfs within 67 pc of the Sun
• Extrasolar planets and brown dwarfs around A-F type stars. I. Performances of radial velocity measurements, first analyses of variations
• The Multiplicity of the Hyades and its Implications for Binary Star Formation and Evolution
• Extrasolar planets and brown dwarfs around A-F type stars VI. High precision RV survey of early type dwarfs with HARPS
• A near-infrared interferometric survey of debris disc stars. III. First statistics based on 42 stars observed with CHARA/FLUOR
• A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER
• Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars
• Proper-motion binaries in the Hipparcos Catalogue. Comparison with radial velocity data
• Searching for faint companions with VLTI/PIONIER. I. Method and first results
• Astrometric Orbits for Hipparcos Stochastic Binaries
• Deep infrared imaging of close companions to austral A- and F-type stars
• On the sensitivity of closure phases to faint companions in optical long baseline interferometry

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• A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER
• A near-infrared interferometric survey of debris-disc stars. V. PIONIER search for variability
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• Stellar Multiplicity and Debris Disks: An Unbiased Sample
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• A realistic two-dimensional model of Altair
• Kuiper belt structure around nearby super-Earth host stars
• Orbits for eighteen visual binaries and two double-line spectroscopic binaries observed with HRCAM on the CTIO SOAR 4m telescope, using a new Bayesian orbit code based on Markov Chain Monte Carlo
• SPOTS: The Search for Planets Orbiting Two Stars. III. Complete Sample and Statistical Analysis
• The wavelength dependence of interstellar polarization in the Local Hot Bubble
• A near-infrared interferometric survey of debris-disk stars. VII. The hot/warm dust connection
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• First L band detection of hot exozodiacal dust with VLTI/MATISSE
• The Interferometric Binary Epsilon Cancri in Praesepe: Precise Masses and Age
• HR 10: A main-sequence binary with circumstellar envelopes around both components. Discovery and analysis
• Prospects for the characterisation of exo-zodiacal dust with the VLTI
• Review and prospects of hot exozodiacal dust research for future exo-Earth direct imaging missions
• Interferometric Detection and Orbit Modeling of the Subcomponent in the Hot-dust System $\kappa$ Tuc A: A Low-mass Star on an Eccentric Orbit in a Hierarchical-quintuple System
• Follow-up of three exocomet-host candidates