SUMMARY OF PROPOSAL 42021 DR. MICHAEL FRANCIS CORCORAN GODDARD SPACE FLIGHT CENTER MD USA 20771 GREENBELT CODE 668 E-mail: CORCORAN@BARNEGAT.GSFC.NASA.GOV Tel: 1-301-286-5576 Fax: 1-301-286-1629 Medium: 4GBDAT Subject: STARS Title: COLLIDING WIND X-RAY EMISSION IN GAMMA VELORUM Abstract: Gamma Velorum (WC8+O9I) is a central object for the new and emerging field of colliding--wind studies. It is an eccentric Wolf-Rayet +O-star binary, with a period of 78.5 days. Understanding of colliding wind X-ray emission from Gamma Velorum has been significantly advanced by ASCA observations at phases 0.4 and 0.5. Detailed modelling of these ASCA observations using hydrodynamic simulations of colliding winds have enabled the first determination of stellar wind parameters by X-ray spectroscopy. We wish to extend our phase coverage of Gamma Vel. These observations will enable us to obtain a more complete picture of colliding winds, such as how binary separation affects X-ray emission, and enable more detailed spectral modelling of the system. Co-Is: 1 IAN STEVENS BIRMINGHAM UK (No Co-I contact data) 2 ALLAN WILLIS UCL UK 3 ANDREW POLLOCK C&S UK Target Name PRI RA Dec Time TC Off GIS SIS_Cts Obs ------------------- --- -------- -------- ---- -- --- --- ------- --- GAM VEL (PHASE 0) 0 122.3825 -47.3367 30 Y N P 0.03000 1 REMARKS: OBSERVATION COULD ALSO START ON 8 JUN 1996 FOR 30 KSEC Co-Ordinated Ob: Start: Mar 22, 1996 at 00 UT Stop: Mar 22, 1996 at 820 UT REMARKS: OBSERVATION COULD ALSO START ON 26 JUL 1996 FOR 20 KSEC Co-Ordinated Ob: Start: May 8, 1996 at 00 UT Stop: May 8, 1996 at 830 UT REMARKS: OBSERVATION COULD ALSO START ON 14 JUL 1996 FOR 20 KSEC. Co-Ordinated Ob: Start: Apr 26, 1996 at 00 UT Stop: Apr 26, 1996 at 533 UT