Disk and wind interaction in the young stellar object MWC 297 spatially resolved with AMBER/VLTI
de Wit, W-J
Le Coarer, E
Domiciano de Souza, A
Hernandez Utrera, O
Le Contel, D
Le Contel, J-M
von der Lühe, O
Astronomy and Astrophysics
© ESO 2007
The young stellar object MWC 297 is an embedded B1.5Ve star exhibiting strong hydrogen emission lines and a strong near-infrared continuum excess. This object has been observed with the VLT interferometer equipped with the AMBER instrument during its first commissioning run. AMBER/VLTI is currently the only near infrared interferometer that can observe spectrally dispersed visibilities. MWC 297 has been spatially resolved in the continuum with a visibility of 0.50+0.08 −0.10 as well as in the Brγ emission line where the visibility decreases to 0.33±0.06. This change in the visibility with wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and of a stellar wind traced by the Brγ emission line and whose apparent size is 40% larger. We validate this interpretation by building a model of the stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric visibilities. We also reproduce the shape of the visibilities in the Brγ line as well as the profile of this line obtained at an higher spectral resolution with the VLT/ISAAC spectrograph, and those of the Hα and Hβ lines. The disk and wind models yield a consistent inclination of the system of approximately 20◦. A picture emerges in which MWC 297 is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing wind that has a much higher velocity in the polar region than at the equator. The AMBER/VLTI unique capability of measuring spectral visibilities therefore allows us for the first time to compare the apparent geometry of a wind with the disk structure in a young stellar system.
The AMBER project4 was founded by the French Centre National de la Recherche Scientifique (CNRS), the Max Planck Institute für Radioastronomie (MPIfR) in Bonn, the Osservatorio Astrofisico di Arcetri (OAA) in Firenze, the French Region "Provence Alpes Côte D’Azur" and the European Southern Observatory (ESO). The CNRS funding has been made through the Institut National des Sciences de l’Univers (INSU) and its Programmes Nationaux (ASHRA, PNPS, PNP). The OAA co-authors acknowledge partial support from MIUR grants to the Arcetri Observatory: A LBT interferometric arm, and analysis of VLTI interferometric data and From Stars to Planets: accretion, disk evolution and planet formation and from INAF grants to the Arcetri Observatory Stellar and Extragalactic Astrophysics with Optical Interferometry. C. Gil work was supported in part by the Fundação para a Ciência e a Tecnologia through project POCTI/CTE-AST/55691/2004 from POCTI, with funds from the European program FEDER.
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.
Astronomy and Astrophysics, 2007, Vol. 464, Number 1, pp. 43-53