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Pre-Main Sequence Binaries: The ESO Imaging Survey

Published online by Cambridge University Press:  12 April 2016

H. Zinnecker ,
W. Brandner  and
B. Reipurth
H. Zinnecker
Affiliation:
Institut für Astronomie und Astrophysik, Universität Würzburg, D-8700 Würzburg, Germany
W. Brandner
Affiliation:
Institut für Astronomie und Astrophysik, Universität Würzburg, D-8700 Würzburg, Germany
B. Reipurth
Affiliation:
European Southern Observatory, La Silla, Chile

Abstract

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We have observed a complete sample of southern Hα emission line pre-main sequence (PMS) stars associated with the nearby dark clouds Chamaeleon and Ophiuchus in an effort to detect binary companions. We have used the high resolution CCD camera SUSI (0.13″ /pixel) at the ESO 3.5m New Technology Telescope (NTT). The observations were carried out in the Gunn z filter (0.95μ). As a result, we have discovered 28 companions out of 160 objects surveyed in the range of angular separation 0″.5 – 10″. We present histograms of semi-major axes and of brightness ratios of these PMS binaries. Taking small incompleteness corrections into account, the frequency of PMS binaries with semi-major axes in the range 100-1500 AU is 20%, while it is only 15% in same range for solar-type Main Sequence (MS) stars. Extrapolation yields a total PMS binary frequency of 70%. Evolutionary and environmental implications are briefly discussed.

Type
Pre-Main Sequence & Young Binaries
Information
International Astronomical Union Colloquium , Volume 135: Complementary Approaches to Double and Multiple Star Research , 1992 , pp. 50 - 59
Copyright
Copyright © Astronomical Society of the Pacific 1992

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