Issue |
A&A
Volume 523, November-December 2010
|
|
---|---|---|
Article Number | A42 | |
Number of page(s) | 9 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/200810361 | |
Published online | 16 November 2010 |
Multi-wavelength study of the disk around the very low-mass star Par-Lup3-4⋆
1
Centro de Astrobiología (INTA-CSIC); LAEFF, P.O. Box 78,
28691
Villanueva de la Cañada,
Spain
e-mail: nhuelamo@cab.inta-csic.es
2
Laboratoire d’Astrophysique, Observatoire de Grenoble,
BP 53,
38041
Grenoble Cedex 9,
France
3
Astronomy Dpt., 601 Campbell Hall, UC Berkeley,
CA
94720
Berkeley,
USA
4
European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748
Garching,
Germany
5
Instituto de Astrofísica de Andalucía,
CSIC, Apdo. 3004,
18080
Granada,
Spain
6
Calar Alto Observatory, Centro Astronómico Hispano Alemán,
Almería,
Spain
7
European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Vitacura,
Santiago,
Chile
8
Atacama Large Millimeter/Submillimeter Array, Joint ALMA Office,
Av. Apoquindo 3650, Piso 18, Las Condes, Santiago, Chile
9
Max-Planck-Institut für Astronomie, Koenigstuhl 17, 69117
Heidelberg,
Germany
Received:
10
June
2008
Accepted:
27
August
2010
Context. Par-Lup3-4 is a very low-mass star (spectral type M5) in the Lupus III star-forming region. It shows spectroscopic evidence of accretion and mass-loss. In the optical and near-infrared, the object is underluminous by ≈ 4 mag when compared to objects of similar mass in the same association.
Aims. The aim of this work is to characterize the circumstellar environment of Par-Lup3-4 to better understand the origin of its underluminosity.
Methods. We have analyzed high angular resolution near-IR observations and searched for extended emission from a disk and/or an envelope. We have studied the spectral energy distribution (SED) of the target from the optical to the sub-millimeter regime, and compared it to a grid of radiative transfer models of circumstellar disks. Since the target is strongly variable, we modeled two different near-infrared datasets.
Results. The SED of Par-Lup3-4 resembles that of objects with edge-on disks seen in scattered light, that is, a double peaked-SED and a dip at ~10 μm. The diffraction-limited infrared observations do not show obvious extended emission, allowing us to put an upper limit of ~20 AU to the disk outer radius. Par-Lup3-4 is probably in a Class II (rather than a Class I) evolutionary stage, which is indicated by the lack of extended emission together with the non detection of a strong 9.8 μm silicate in absorption. This last feature is indeed seen in emission. We fitted the whole SED of Par-Lup3-4 with a single disk model. Our modeling predicts a disk inclination of 81° ± 6°, which agrees well with previous estimates, and provides a natural explanation for the under-luminosity of the target. The detection of the silicate feature in emission at such a high inclination might be related to a more complex disk structure (e.g. asymmetries, inhomogeneities) than the one assumed here. Our analysis allows us to put constraints on the disk inner radius, Rin ≤ 0.05 AU, which is very close to the dust sublimation radius, and the maximum size of the dust grains, amax ≥ 10 μm, which indicates that dust processing has already taken place in Par-Lup3-4. Some of the derived disk parameters vary depending on the modeled near-infrared data-set, which emphasizes the importance of taking variability into account when modeling the SED of young stellar objects.
Key words: stars: pre-main sequence / circumstellar matter / stars: individual: Par-Lup3-4
© ESO, 2010
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