Reference : Searching for faint companions with VLTI/PIONIER. I. Method and first results
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/109531
Searching for faint companions with VLTI/PIONIER. I. Method and first results
English
Absil, Olivier mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)]
Le Bouquin, J.-B. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Berger, J.-P. [European Southern Observatory, Casilla 19001, Santiago 19, Chile]
Lagrange, A.-M. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Chauvin, G. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France; Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany]
Lazareff, B. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Zins, G. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Haguenauer, P. [European Southern Observatory, Casilla 19001, Santiago 19, Chile]
Jocou, L. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Kern, P. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Millan-Gabet, R. [NASA Exoplanet Science Institute (NExScI), California Institute of Technology, Pasadena, CA, 91125, USA]
Rochat, S. [Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1/CNRS-INSU, Grenoble, France]
Traub, W. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA]
1-Nov-2011
Astronomy and Astrophysics
EDP Sciences
535
A68
Yes (verified by ORBi)
International
0004-6361
1432-0746
Les Ulis
France
[en] techniques: interferometric ; binaries: close ; stars: low mass ; brown dwarfs ; planetary systems
[en] Context. A new four-telescope interferometric instrument called PIONIER has recently been installed at VLTI. It provides improved imaging capabilities together with high precision. <BR /> Aims: We search for low-mass companions around a few bright stars using different strategies, and determine the dynamic range currently reachable with PIONIER. <BR /> Methods: Our method is based on the closure phase, which is the most robust interferometric quantity when searching for faint companions. We computed the χ[SUP]2[/SUP] goodness of fit for a series of binary star models at different positions and with various flux ratios. The resulting χ[SUP]2[/SUP] cube was used to identify the best-fit binary model and evaluate its significance, or to determine upper limits on the companion flux in case of non-detections. <BR /> Results: No companion is found around <ASTROBJ>Fomalhaut</ASTROBJ>, <ASTROBJ>tau Cet</ASTROBJ> and <ASTROBJ>Regulus</ASTROBJ>. The median upper limits at 3σ on the companion flux ratio are respectively of 2.3 × 10[SUP]-3[/SUP] (in 4 h), 3.5 × 10[SUP]-3[/SUP] (in 3 h) and 5.4 × 10[SUP]-3[/SUP] (in 1.5 h) on the search region extending from 5 to 100 mas. Our observations confirm that the previously detected near-infrared excess emissions around Fomalhaut and tau Cet are not related to a low-mass companion, and instead come from an extended source such as an exozodiacal disk. In the case of <ASTROBJ>del Aqr</ASTROBJ>, in 30 min of observation, we obtain the first direct detection of a previously known companion, at an angular distance of about 40 mas and with a flux ratio of 2.05 × 10[SUP]-2[/SUP] ± 0.16 × 10[SUP]-2[/SUP]. Due to the limited u,v plane coverage, its position can, however, not be unambiguously determined. <BR /> Conclusions: After only a few months of operation, PIONIER has already achieved one of the best dynamic ranges world-wide for multi-aperture interferometers. A dynamic range up to about 1:500 is demonstrated on unresolved targets, but significant improvements are still required to reach the ultimate goal of directly detecting hot giant extrasolar planets. Based on observations obtained at the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI), Paranal, Chile.
Researchers
http://hdl.handle.net/2268/109531
10.1051/0004-6361/201117719
http://adsabs.harvard.edu/abs/2011A%26A...535A..68A
http://www.aanda.org/index.php?option=com_article&access=doi&doi=10.1051/0004-6361/201117719&Itemid=129 Copyright ESO 2011, published by EDP Sciences
http://de.arxiv.org/abs/1110.1178

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