## SUMMARY OF PROPOSAL 62013

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

NASA-GSFC/USRA
CODE 660.2
GREENBELT
MD USA 20771
Tel: 301-286-5576 Fax: 301-286-1629
Medium: CD ROM
Subject: STARS

#### ABSTRACT

The extremely luminous, extremely massive star $\eta$ Car is perhaps the Galaxy's most enigmatic object. Periodic emission line equivalent width variations and changes in Pa-$\gamma$ radial velocity variations by Damineli and collaborators provide the strongest evidence to date that the star is a binary. If true this revises the fundamental understanding of the evolution of the system, the connection of $\eta$ Car to the Luminous Blue Variables (LBVs), and the nature of its atmospheric instabilities and the Great Eruption'' of the last century. {\it ASCA} can make perhaps the most conclusive test of this model by determining the level of variation in the hard X-ray spectrum as a result of colliding-winds during the next predicted periastron passage, expected to occur on Jan 1, 1998

#### TARGETS

1)ETA CAR/PERIASTRON?
1
161.2604-59.6803 50 ksN
N
P
0.40000
1
2)ETA CAR/POST-PERIAS.
1
161.2604-59.6803 20 ksN
N
P
0.60000
1

#### TARGET 1

WE WANT THIS OBSERVATION DURING THE DEC-FEB WINDOW; THE EXACT START TIME IS NOT IMPORTANT.

#### TARGET 2

WE WANT THIS OBSERVATION DURING THE JUN-AUG WINDOW; THE EXACT START TIME IS NOT IMPORTANT.