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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 276835.0, MPI für Astronomie / Publikationen_mpia
First VLTI/MIDI observations of a Be star: Alpha Arae
Authors:Chesneau, O.; Meilland, A.; Rivinius, T.; Stee, Ph.; Jankov, S.; Domiciano de Souza, A.; Graser, U.; Herbst, T.; Janot-Pacheco, E.; Koehler, R.; Leinert, C.; Morel, S.; Paresce, F.; Richichi, A.; Robbe-Dubois, S.
Date of Publication (YYYY-MM-DD):2005
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:Astronomy and Astrophysics
Start Page:275
End Page:287
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present the first VLTI/MIDI observations of the Be star alpha Ara (HD 158 427), showing a nearly unresolved circumstellar disk in the N band. The interferometric measurements made use of the UT1 and UT3 telescopes. The projected baselines were 102 and 74 meters with position angles of 7 ° and 55°, respectively. These measurements put an upper limit on the envelope size in the N band under the uniform disk approximation of phimax= 4±1.5 mas, corresponding to 14 R*, assuming R*=4.8 Râ_™ and the Hipparcos distance of 74 pc. On the other hand the disk density must be large enough to produce the observed strong Balmer line emission. In order to estimate the possible circumstellar and stellar parameters we have used the SIMECA code developed by Stee et al. (1995, A&A, 300, 219) and Stee & Bittar (2001, A&A, 367, 532). Optical spectra taken with the échelle instrument Heros and the ESO-50 cm telescope, as well as infrared ones from the 1.6m Brazilian telescope were used together with the MIDI spectra and visibilities. These observations place complementary constraints on the density and geometry of the alpha Ara circumstellar disk. We discuss the potential truncation of the disk by a companion and we present spectroscopic indications of a periodic perturbation of some Balmer lines.
Free Keywords:techniques: high angular resolution; techniques: interferometric; stars: emission- line; Be; stars: winds; outflows; stars: individual: alpha Ara; circumstellar matter
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL: bib_query?b... [ID No:1]
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