## SUMMARY OF PROPOSAL 82023

#### DR MICHAEL F. CORCORAN CORCORAN@BARNEGAT.GSFC.NASA.GOV

GSFC/USRA
CODE 662 GSFC
GREENBELT
MD USA 20771
Tel: 301-286-5576 Fax: 301-286-1629
Medium: CD ROM
Subject: STARS

#### ABSTRACT

We propose to crown our semi-annual \ASCA\ monitoring program of the touchstone colliding-wind 7.94-year binary star WR140 (WC7+O) with a detailed series of \ASCA\ observations just prior to the 2001.14 periastron passage. Because of the high eccentricity, both emission and absorption are predicted to evolve very rapidly near periastron. A long look with \ASCA\ provides the first chance ever to observe in detail the change in $L_{x}$ and $N_{H}$ to allow critical tests of numerical hydrodynamic models. Of particular interest is to determine whether the rapid changes seen in the X-ray flux from $\eta$ Car near its putative periastron passage'' are also seen in WR 140.

1)WR 140
B
305.1162 43.8545
750 ks
N
N
P
1.60000
1
2)WR 140
B
305.1162 43.8545
250 ks
N
N
P
3.00000
1

#### TARGET 1

DURING FIRST OBSERVING WINDOW (15 APR 2000 TO 08 JUL 2000)

#### TARGET 2

DURING SECOND OBSERVING WINDOW (30 SEP 2000 TO 20 DEC 2000)