Berger, J. -P. and Monnier, J. D. and Millan-Gabet, R. and Renard, S. and Pedretti, E. and Traub, W. and Bechet, C. and Benistry, M. and Carleton, N. and Haguenauer, P. and Kern, P. and Labeye, P. and Longa, F. and Lacasse, M. and Malbet, F. and Perraut, K. and Ragland, S. and Schloerb, P. and Schuller, P. A. and Thiébaut, E. (2011) First astronomical unit scale image of the GW Orionis triple system: Direct detection of a new stellar companion. Astronomy and Astrophysics, 529 . Art. No. L1. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20110504-073757041
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Context. Young and close multiple systems are unique laboratories to probe the initial dynamical interactions between forming stellar systems and their dust and gas environment. Their study is a key building block to understanding the high frequency of main-sequence multiple systems. However, the number of detected spectroscopic young multiple systems that allow dynamical studies is limited. GW Orionis is one such system. It is one of the brightest young T Tauri stars and is surrounded by a massive disk. Aims. Our goal is to probe the GW Orionis multiplicity at angular scales at which we can spatially resolve the orbit. Methods. We used the IOTA/IONIC3 interferometer to probe the environment of GW Orionis with an astronomical unit resolution in 2003, 2004, and 2005. By measuring squared visibilities and closure phases with a good UV coverage we carry out the first image reconstruction of GW Ori from infrared long-baseline interferometry. Results. We obtained the first infrared image of a T Tauri multiple system with astronomical unit resolution. We show that GW Orionis is a triple system, resolve for the first time the previously known inner pair (separation ρ ~ 1.4 AU) and reveal a new more distant component (GW Ori C) with a projected separation of ~ 8 AU with direct evidence of motion. Furthermore, the nearly equal (2:1) H-band flux ratio of the inner components suggests that either GW Ori B is undergoing a preferential accretion event that increases its disk luminosity or that the estimate of the masses has to be revisited in favour of a more equal mass-ratio system that is seen at lower inclination. Conclusions. Accretion disk models of GW Ori will need to be completely reconsidered because of this outer companion C and the unexpected brightness of companion B.
|Additional Information:||© 2011 ESO. Received 27 November 2010. Accepted 1 March 2011. Published online 25 March 2011. This work was supported by ASHRA, PNPS/INSU, and Michelson fellowship program. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France and getCal software from the NASA Exoplanet Science Institute, Caltech. Bibliographic references were provided by the SAO/NASA Astrophysics Data System. IONIC-3 has been developed by LAOG and CEA-LETI, and funded by the CNRS and CNES. We thank Russel White, Lee Hartmann and S. Meimon for useful discussions.|
|Subject Keywords:||binaries: general; stars: variables: T Tauri; Herbig Ae/Be; accretion, accretion disks; techniques: interferometric|
|Official Citation:||First astronomical unit scale image of the GW Orionis triple system - Direct detection of a new stellar companion J.-P. Berger, J. D. Monnier, R. Millan-Gabet, S. Renard, E. Pedretti, W. Traub, C. Bechet, M. Benisty, N. Carleton, P. Haguenauer, P. Kern, P. Labeye, F. Longa, M. Lacasse, F. Malbet, K. Perraut, S. Ragland, P. Schloerb, P. A. Schuller and E. Thiébaut A&A 529 L1 (2011) DOI: 10.1051/0004-6361/201016219|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||04 May 2011 16:59|
|Last Modified:||26 Dec 2012 13:12|
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