1998A&A...334..592S

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 8" of any of our targets. We did find 23 faint objects outside a separation of 8". For 12 of these, we have color information that implies they are background objects. Our sensitivity limit for companions separated by more than 1" is better than {DELTA}I=10mag. This limit degrades to {DELTA}I=5mag at a separation of about 0.2". For the median apparent magnitude, I=11mag, and median age, 10⁷yr, 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 2km/s 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.