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Modeling Spitzer Observations of VV Ser. I. The Circumstellar Disk of a UX Orionis Star

Pontoppidan, Klaus M. and Dullemond, Cornelis P. and Blake, Geoffrey A. and Boogert, A. C. Adwin and van Dishoeck, Ewine F. and Evans, Neal J., II and Kessler-Silacci, Jacqueline and Lahuis, Fred (2007) Modeling Spitzer Observations of VV Ser. I. The Circumstellar Disk of a UX Orionis Star. Astrophysical Journal, 656 (2). pp. 980-990. ISSN 0004-637X. doi:10.1086/510570.

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We present mid-infrared Spitzer IRS spectra of the UX Orionis star VV Ser, combined with interferometric and spectroscopic data from the literature covering UV to submillimeter wavelengths. The full set of data are modeled by an axisymmetric Monte Carlo radiative transfer code to test the prediction of Dullemond et al. that disks around UX Orionis stars are self-shadowed and seen nearly edge-on. Our model is consistent with all the available observational constraints, providing strong support for this interpretation. The mid-infrared SED is declining and exhibits weak silicate emission features, consistent with a self-shadowed geometry. MIPS imaging shows that the disk has a small grain dust mass as low as 0.8 × 10^(-7) M_⊙, which may be due to strong grain growth and settling. The grains in the upper layers of the puffed-up inner rim must be small (0.01-0.4 μm) to reproduce the colors (R_V ~ 3.6) of the optical light curve, while the silicate emission features indicate that grains in the outer disk (>1-2 AU) are somewhat larger (0.3-3.0 μm). If grains in the inner disk are small, the location of the puffed-up inner rim is estimated to be at 0.7-0.8 AU. This is almost twice the rim radius estimated from near-infrared interferometry. Since larger (more gray) grains are able to penetrate closer to the star for the same dust sublimation temperature, we suggest a model in which large grains in the disk midplane reach to within 0.25 AU of the star, while small grains in the disk surface create a puffed-up rim at ~0.7-0.8 AU.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Pontoppidan, Klaus M.0000-0001-7552-1562
Blake, Geoffrey A.0000-0003-0787-1610
van Dishoeck, Ewine F.0000-0001-7591-1907
Evans, Neal J., II0000-0001-5175-1777
Additional Information:© 2007 The American Astronomical Society. Received 2005 September 12; accepted 2006 September 29. The authors are grateful to Josh Eisner for providing a table with the PTI visibilities of VV Ser and Remo Tilanus for obtaining the SCUBA map in service mode. Support for this work was provided by NASA through Hubble Fellowship grant 01201.01, awarded by the Space Telescope Science Institute, which is operated by AURA, Inc., for NASA, under contract NAS5-26555. Astrochemistry in Leiden is supported by a Spinoza grant of the Netherlands Organization for Scientific Research (NWO). Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through contracts 1224608 and 1230779, issued by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. This research was supported by the European Research Training Network The Origin of Planetary Systems (PLANETS, contract HPRN-CT-2002-00308). The anonymous referee is thanked for constructive comments that have significantly improved the paper.
Funding AgencyGrant Number
NASA Hubble Fellowship01201.01
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
European Research Training NetworkHPRN-CT-2002-00308
Subject Keywords:accretion, accretion disks; circumstellar matter; infrared : stars; stars : formation; stars : pre-main-sequence
Issue or Number:2
Record Number:CaltechAUTHORS:20100223-140851773
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Official Citation:Modeling Spitzer Observations of VV Ser. I. The Circumstellar Disk of a UX Orionis Star Klaus M. Pontoppidan, Cornelis P. Dullemond, Geoffrey A. Blake, A. C. Adwin Boogert, Ewine F. van Dishoeck, Neal J. Evans II, Jacqueline Kessler-Silacci, and Fred Lahuis 2007 ApJ 656 980-990 doi: 10.1086/510570
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17567
Deposited By: Tony Diaz
Deposited On:02 Mar 2010 17:38
Last Modified:08 Nov 2021 23:36

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