EDP Sciences
Free access
Volume 496, Number 3, March IV 2009
Page(s) 777 - 786
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:200810730
Published online 14 January 2009
A&A 496, 777-786 (2009)
DOI: 10.1051/0004-6361:200810730

Edge-on disk around the T Tauri star [MR81] H$\alpha$ 17 NE in Corona Australis

R. Neuhäuser1, S. Krämer1, M. Mugrauer1, R. Köhler2, 3, T. O. B. Schmidt1, M. Ammler-von Eiff4, J. Alves5, S. Fiedler1, and N. Vogt6, 7

1  Astrophysikalisches Institut und Universitäts-Sternwarte, Friedrich-Schiller-Universität Jena, Schillergässchen 2-3, 07745 Jena, Germany
    e-mail: rne@astro.uni-jena.de
2  ZAH Landessternwarte, Königstuhl, 69117 Heidelberg, Germany
3  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
4  Centro de Astronomia e Astrofísica da Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
5  Calar Alto Observatory, Centro Astronomico Hispano-Aleman, C/q Jesus Durban Remon 2-2, 04004 Almeria, Spain
6  Departamento de Física y Astronomía, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Valparaíso, Chile
7  Instituto de Astronomía, Universidad Catolica del Norte, Avda. Angamos 0610, Antofagasta, Chile

Received 1 August 2008 / Accepted 14 November 2008

Aims. Using the speckle camera SHARP at the 3.5 m ESO NTT, Köhler and collaborators found an object $\sim $3.5 mag fainter in K only $1.3^{\prime \prime}$ north-east of the T Tauri star [MR81] H$\alpha 17$ in the Corona Australis (CrA) star-forming region, which could be either a brown dwarf or a T Tauri star with an edge-on disk. We attempt to study this faint object in detail.
Methods. We acquired deep VLT NACO near-infrared images at three epochs to determine, whether [MR81] H$\alpha 17$ and the nearby faint object are comoving and to measure the infrared colors of both objects. We obtained optical and infrared spectra of both objects with the VLT using FORS and ISAAC, respectively, to determine spectral types and temperatures as well as ages and masses.
Results. The T Tauri star [MR81] H$\alpha 17$ and the faint nearby object have a projected separation of 1369.58 mas, i.e. 178 AU at 130 pc. They share the same proper motion (~$ 5 \sigma$), so that they most certainly form a bound binary pair. The apparently fainter component [MR81] H$\alpha 17$ NE has a spectral type of M2e, while the apparently brighter component [MR81] H$\alpha 17$ SW, the previously known T Tauri star, has a spectral type of M4-5e. We can identify a nearly edge-on disk around [MR81] H$\alpha 17$ NE by visual inspection, which has a diameter of at least 30 to 50 AU. We are able to detect strong emission lines in [MR81] H$\alpha 17$ NE, which are almost certainly due to ongoing accretion. The NE object is detectable only by means of its scattered light.
Conclusions. If both objects are co-eval (2–3 Myr) and located at the same distance ($\sim $130 pc as CrA), then the apparently fainter [MR81] H$\alpha 17$ NE is more massive (primary) component with a nearly edge-on disk and the apparently brigther component [MR81] H$\alpha 17$ SW is less massive (companion). Both are low-mass T Tauri stars with masses of $\sim $0.5 and $0.23 \pm 0.05$ $M_{\odot}$, respectively.

Key words: astrometry -- stars: binaries: visual -- stars: formation -- stars: pre-main sequence

© ESO 2009