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Astron. Astrophys. 354, L9-L12 (2000)

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Letter to the Editor

On the possibility of ground-based direct imaging detection of extra-solar planets: the case of TWA-7 *

R. Neuhäuser 1, W. Brandner 2, A. Eckart 1, E. Guenther 3, J. Alves 4, T. Ott 1, N. Huélamo 1 and M. Fernández 1

1 MPI für Extraterrestrische Physik, Giessenbachstrasse 1, 85740 Garching, Germany
2 University of Hawaii, Institute for Astronomy, 2680 Woodlawn Dr., Honolulu, HI 96822, USA
3 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
4 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany

Received 23 September 1999 / Accepted 23 December 1999


We show that ground-based direct imaging detection of extra-solar planets is possible with current technology. As an example, we present evidence for a possible planetary companion to the young T Tauri star 1RXSJ104230.3-334014 (=TWA-7), discovered by ROSAT as a member of the nearby TW Hya association. In an HST NICMOS F160W image, an object is detected that is more than 9 mag fainter than TWA-7, located [FORMULA] south-east at a position angle of [FORMULA]. One year later using the ESO-NTT with the SHARP speckle camera, we obtained H- and K-band detections of this faint object at a separation of [FORMULA] and a position angle of [FORMULA]. Given the known proper motion of TWA-7, the pair may form a proper motion pair. If the faint object orbits TWA-7, then its apparent magnitudes of H=[FORMULA] and K=[FORMULA] mag yield absolute magnitudes consistent with a [FORMULA] yr old [FORMULA] M[FORMULA] mass object according to the non-gray theory by Burrows et al. (1997). At [FORMULA] pc, the angular separation of [FORMULA] corresponds to [FORMULA] AU, clearly within typical disk sizes. However, position angles and separations are slightly more consistent with a background object than with a companion.

Key words: stars: binaries: visual – stars: individual: TWA-7 – stars: late-type – stars: pre-main sequence

* Based on observations obtained at the European Southern Observatory, La Silla (ESO Proposals 62.I-0418 and 63.N-0178), and on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.

Send offprint requests to: R. Neuhäuser (rne@mpe.mpg.de)

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© European Southern Observatory (ESO) 2000

Online publication: January 31, 2000