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

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 <sup>3

1</sup> 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 of any of our targets. We did find 23 faint objects outside a separation of . For 12 of these, we have color information that implies they are background objects. Our sensitivity limit for companions separated by more than is better than mag. This limit degrades to mag at a separation of about . For the median apparent magnitude, mag, and median age, 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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