The Binary Frequency among Solar-Type Stars in Young Clusters: CYCLE4 High
Abstract
Recent ground-based observations have led to the unexpected conclusion that most and possibly all of the youngest, optically-visible solar-type pre-main sequence stars are members of binary or multiple star systems. However, this result is based solely on examination of stars located in sparsely populated, nearby star-forming complexes (e.g. Taurus) which are not representative of those that produce most of the stars which populate the Milky Way: giant molecular clouds (GMCs) which give birth to rich, dense clusters. We propose to take advantage of the high angular resolution and relatively wide field afforded by WFPC2 on HST to search for binary stars with angular separations of between 0.1" and 1" among a sample of about 120 stars located in 2 young (age approximately 1 Myr) clusters embedded within the nearest GMC: Orion (d = 460 pc). A sample this size will enable a statistically significant comparison between the binary frequency in the separation range 46 AU < r < 460 AU found for these young clusters, and that found for (1) older stars in the solar-neighborhood (expected binaries about 24/120); and (2) Taurus where most or all stars are binaries (expected binaries about 65/120). Our observations should thus provide a test of the hypothesis that all stars are born in binary/multiple systems, not only in regions like Taurus, but in rich clusters as well.
- Publication:
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HST Proposal
- Pub Date:
- January 1994
- Bibcode:
- 1994hst..prop.5355S