A low optical depth region in the inner disk of the Herbig Ae star HR 5999
Abstract
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.
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.Attached Files
Published - Benisty2011p15737Astron_Astrophys.pdf
Files
Name | Size | Download all |
---|---|---|
md5:827d2494dec2661fcb5bae91f74202c1
|
1.6 MB | Preview Download |
Additional details
- Eprint ID
- 25283
- Resolver ID
- CaltechAUTHORS:20110912-070013015
- ASI-INAF I/016/07/0
- Agenzia Spaziale Italiana (ASI)
- Istituto Nazionale di Astrofisica (INAF)
- Created
-
2011-09-12Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field