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Published November 1993 | Published
Journal Article Open

The multiplicity of T Tauri stars in the star forming regions Taurus-Auriga and Ophiuchus-Scorpius: A 2.2 micron speckle imaging survey

Abstract

We present the results of a magnitude limited (K < =8.5 mag) speckle imaging survey of 69 T Tauri stars in the star forming regions Taurus-Auriga and Ophiuchus-Scorpius. Thirty-three companion stars were found with separations ranging from 0."07 to 2."5; nine are new detections. This survey reveals a distinction between the classical T Tauri stars (CTTS) and the weak-lined T Tauri stars (WTTS) based on the binary star frequency as a function of separation: the WTTS binary star distribution is enhanced at the closer separations (<50 AU) relative to the CTTS binary star distribution. We suggest that the nearby companion stars shorten the accretion time scale in multiple star systems, thereby accounting for the presence of WTTS that are coeval with many CTTS. The binary star frequency in the projected linear separation range 16 to 252 AU for T Tauri stars (60[± 17]%) is a factor of 4 greater than that of the solar-type main-sequence stars (16[±3]%). Given the limited separation range of this survey, the rate at which binaries are detected suggests that most, if not all, T Tauri stars have companions. We propose that the observed overabundance of companions of T Tauri stars is an evolutionary effect, in which triple and higher order T Tauri stars are disrupted by close encounters with another star or system of stars.

Additional Information

© 1993 American Astronomical Society. Received 1993 March 17; revised 1993 July 28. We thank the staff of Palomar Observatory, especially the night assistants Juan Carrasco and Will McKinley, for their assistance during the observations and J. Graham, D. McCarthy, A. Sargent, M. Simon, and B. T. Soifer for many helpful discussions. We are grateful to S. Beckwith, P. Gorham, C. HanifF, C. Koresko, and S. Kulkami for both shared telescope time and productive interactions and we are indebted to Fred Walter who kindly provided a target list of x-ray identified sources in the Oph-Sco regions prior to publication as well as many helpful comments in reviewing this paper. Tom Prince and the Caltech Conconcurrent Supercomputing Facility generously provided time on the Caltech NCUBE supercomputer for the speckle imaging data reduction. This research has made use of the SIMBAD data base, operated at CDS, Strasbourg, France. Infrared astrophysics at Caltech is supported by a grant from the NSF. A. G. currently receives support from NASA through Grant No. HF-1031.01-92A awarded by the Space Telescope Science Institute which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under Contract No. NAS5-26555.

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August 20, 2023
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