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Astron. Astrophys. 334, 592-598 (1998)


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A search for substellar companions around nine weak-lined T-Tauri stars with the Planetary Camera 2 of the Hubble Space Telescope *

Paola Sartoretti 1, Robert A. Brown 2, David W. Latham 3 and Guillermo Torres 3

1 Institut d' Astrophysique de Paris, 98 bis Boulevard Arago, F-75014 Paris, France
2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138, USA

Received 9 December 1997 / Accepted 24 February 1998

Abstract

To search for substellar companions, we have obtained I -band images of 9 weak-lined T-Tauri stars in the Taurus-Auriga star-forming region using the Planetary Camera 2 of the Hubble Space Telescope. Except for a stellar companion close to HBC 407, we found no companions within [FORMULA] of any of our targets. We did find 23 faint objects outside a separation of [FORMULA]. For 12 of these, we have color information that implies they are background objects. Our sensitivity limit for companions separated by more than [FORMULA] is better than [FORMULA] mag. This limit degrades to [FORMULA] mag at a separation of about [FORMULA]. For the median apparent magnitude, [FORMULA] mag, and median age, [FORMULA] yr, of our targets, the above sensitivity limits correspond to companions with 18 and 55 Jupiter masses, respectively.

To complement the imaging program, radial-velocity observations of the 9 stars were obtained using the Center for Astrophysics Digital Speedometers. There is a hint of a long-term acceleration of about 2 km s-1 over ten years in the radial velocity of HBC 407, consistent with the evidence for a close companion to HBC 407 found in the HST images. In addition, one of our targets, HBC 392 was found to be a double-lined spectroscopic binary.

Key words: stars: pre-main sequence – stars: imaging – stars: low-mass, brown dwarfs – planetary systems

* Some of the observations reported here were obtained with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona

Send offprint requests to: P. Sartoretti,(sartoret@iap.fr)

© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998

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