Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4892c Report Date: 09-May-96:20:06 Version: ********** Check-in Date: ********** 1.Proposal Title: DUPLICITY AMONG HYADES STARS CYCLE 3, HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GTO/AST 1004 Sub Category ASTROMETRY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone William H. Jefferys TEXAS, UNIVERSITY OF USA 512-471-4461 PROFESSOR OF ASTRONO ------------------------------------------------------------------------------------ 7. Abstract We propose to use FGS in the TRANS mode to examine, at high angular resolution, a representative sample of probable Hyades cluster members in an effort to establish the incidence of duplicity among Hyades stars. The frequency of multiple stars in stellar systems and populations represents a significant aspect of star formation and stellar evolution. Among Hyades stars brighter than V ~ 12.0, companions should be observable to Delta m ~ 2. Binaries of small Delta m should be readily detectable at V ~ 15. ------------------------------------------------------------------------------------ 8. Scientific Key Words: DUPLICITY; BINARIES; MULTIPLE STARS; HYADES ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 40.25 par: 0 10. Num targs pri: 41 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4892c PI: William H. Jefferys Proposal Title: DUPLICITY AMONG HYADES STARS CYCLE 3, HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ William H. Jefferys TEXAS, UNIVERSITY OF USA George F. Benedict TEXAS, UNIVERSITY OF USA Raynor L. Duncombe TEXAS, UNIVERSITY OF USA Otto G. Franz LOWELL OBSERVATORY USA Laurence W. Fredrick VIRGINIA, UNIVERSITY OF USA Paul D. Hemenway TEXAS, UNIVERSITY OF USA Peter J. Shelus TEXAS, UNIVERSITY OF USA William F. Van Altena YALE UNIVERSITY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Line 1, page 11 defines, for each target, an observation consisting of a set of continuous scans at a scan rate of 0.04 arcsec per sec and a scan length of 1.2 arcsec per interferometer axis. There are 30 scans/observation (total exposure time 900 seconds), sufficient to permit detection of close companions to a Delta- m ~ 2 mag for stars of V