SUMMARY OF PROPOSAL 72003
NASA-GSFC/USRA
CODE 660.2
GREENBELT
MD USA 20771
Tel: 301-286-5576 Fax: 301-286-1629
Medium: CD ROM
Subject: STARS
THE X-RAY LIGHTCURVE OF WR 140: THE CONTINUING STORY
ABSTRACT
We have obtained {\it ASCA} X-ray spectra of the canonical colliding-wind binary star WR 140 (WC7+OB) during the PV, AO1, AO5 and AO6 intervals. We need continuing {\it ASCA} monitoring to measure the variability of the X-ray spectrum through the entire orbit. This X-ray lightcurve will provide the most accurate measure of the interaction region and redefine the physics of colliding-wind systems. The previous {\it ASCA} observations show that the spectrum has changed from a highly-absorbed, predominantly thermal spectrum to a less absorbed but {\it predominantly non-thermal} model. This is a very surprising result, not predicted in standard colliding wind models, and suggests that Fermi acceleration of particles at the wind shock boundary is important.
CO-INVESTIGATORS
| CO-I NAME | INSTITUTE | COUNTRY |
|---|
| THE XMEGA | GROUP | USA |
TARGETS
| TARGET NAME | PRI | RA | DEC | TIME | TC | OFF | GIS | SIS CNT | OBS |
|---|
| 1)WR 140 | A | 305.1162 | 43.8545 | 20 ks | N | N | P | 0.50000 | 2 |
TARGET 1
WE ASK ONE 20 KSEC OBSERVATION IN EACH OBSERVING WINDOW (APR-JUL & OCT-DEC); THE EXACT START TIME OF THE OBSERVATION IN EACH WINDOW IS UNIMPORTANT