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A low optical depth region in the inner disk of the Herbig Ae star HR 5999

Benisty, M. and Renard, S. and Natta, A. and Berger, J. P. and Massi, F. and Malbet, F. and Garcia, P. J. V. and Isella, A. and Mérand, A. and Monin, J. L. and Testi, L. and Thiébaut, E. and Vannier, M. and Weigelt, G. (2011) A low optical depth region in the inner disk of the Herbig Ae star HR 5999. Astronomy and Astrophysics, 531 . Art. No. A84. ISSN 0004-6361.

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Context. Circumstellar disks surrounding young stars are known to be the birthplaces of planetary systems, and the innermost astronomical unit is of particular interest. Near-infrared interferometric studies have revealed a complex morphology for the close environment surrounding Herbig Ae stars. Aims. We present new long-baseline spectro-interferometric observations of the Herbig Ae star, HR 5999, obtained in the H and K bands with the AMBER instrument at the VLTI, and aim to produce near-infrared images at the sub-AU spatial scale. Methods. We spatially resolve the circumstellar material and reconstruct images in the H and K bands using the MiRA algorithm. In addition, we interpret the interferometric observations using models that assume that the near-infrared excess is dominated by the emission of a circumstellar disk. We compare the images reconstructed from the VLTI measurements to images obtained using simulated model data. Results. The K-band image reveals three main elements: a ring-like feature located at ~0.65 AU, a low surface brightness region inside 0.65 AU, and a central spot. At the maximum angular resolution of our observations (B/λ ~ 1.3 mas), the ring is resolved while the central spot is only marginally resolved, preventing us from revealing the exact morphology of the circumstellar environment. We suggest that the ring traces silicate condensation, i.e., an opacity change, in a circumstellar disk around HR 5999. We build a model that includes a ring at the silicate sublimation radius and an inner disk of low surface brightness responsible for a large amount of the near-infrared continuum emission. The model successfully fits the SED, visibilities, and closure phases in the H and K bands, and provides evidence of a low surface brightness region inside the silicate sublimation radius. Conclusions. This study provides milli-arcsecond resolution images of the environment of HR 5999 and additional evidence that in Herbig Ae stars, there is material in a low surface brightness region, probably a low optical depth region, located inside the silicate sublimation radius and of unknown nature. The possibility that the formation of such a region in a thick disk is related to disk evolution should be investigated.

Item Type:Article
Related URLs:
URLURL TypeDescription
Benisty, M.0000-0002-7695-7605
Berger, J. P.0000-0001-5025-0428
Isella, A.0000-0001-8061-2207
Testi, L.0000-0003-1859-3070
Additional Information:© 2011 ESO. Received 6 November 2010. Accepted 8 April 2011. Published online 17 June 2011. Based on observations collected at the VLTI (ESO Paranal, Chile) with programs 080.C-0056, 083.C-0298, 083.C-0144, 083.C- 0334, 083.C-0170, 083.C-0857, 083.C-0864, 083.C-0602, 084.C-0590, 085.C-0769, 085.C-0502. We thank the VLTI team at Paranal. M.B. acknowledges funding from INAF (grant ASI-INAF I/016/07/0). We thank the anonymous referee for useful comments that help improved the manuscript.
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)ASI-INAF I/016/07/0
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Subject Keywords:methods: observational; circumstellar matter; stars: pre-main sequence; stars: variables: T Tauri, Herbig Ae/Be; techniques: interferometric
Record Number:CaltechAUTHORS:20110912-070013015
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Official Citation:A low optical depth region in the inner disk of the Herbig Ae star HR 5999 M. Benisty, S. Renard, A. Natta, J. P. Berger, F. Massi, F. Malbet, P. J. V. Garcia, A. Isella, A. Mérand, J. L. Monin, L. Testi, E. Thiébaut, M. Vannier and G. Weigelt A&A 531 A84 (2011) DOI: 10.1051/0004-6361/201016091
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25283
Deposited By: Ruth Sustaita
Deposited On:12 Sep 2011 14:20
Last Modified:09 Mar 2020 13:18

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