SUMMARY OF PROPOSAL 52015

DR. JEAN-PIERRE CAILLAULT
JPC@AKBAR.PHYSAST.UGA.EDU

UNIVERSITY OF GEORGIA

ATHENS
GEORGIA USA 30602-2451
Tel: 706-542-2883 Fax: 706-542-2492
Medium: 4GBDAT
Subject: STARS

DETERMINING THE NATURE OF THETA-1 ORI C'S X-RAY EMISSION


ABSTRACT

ROSAT HRI soft X-ray observations of the O7 V star Theta-1 Ori C have confirmed the 15.4 day rotational period first discovered from H-alpha and He II observations. This periodicity has also been detected in IUE observations of CIV absorption. These data suggest that Theta-1 Ori C is an oblique magnetic rotator, and, hence, may be the only known magnetic O-star. We propose to observe the Trapezium at Theta-1 Ori C's rotational phases 0.0 and 0.5 in order to determine the origin of its X-ray emission. These data will allow us to distinguish between a varying wind-absorption model and a model where the active-region is eclipsed by the star itself.

CO-INVESTIGATORS
CO-I NAME INSTITUTE COUNTRY
MARC GAGNEJILAUSA
JEFFREY LINSKYJILAUSA
JOHN STAUFFERCFAUSA

TARGETS

TARGET NAMEPRIRADECTIMETCOFFGISSIS CNTOBS
1)TRAPEZIUM
2
 83.8167 -5.3881 100 ksY
N
P
4.00000
2

TARGET 1

NEEDS TO BE OBSERVED AT ANY PHASE 0.0 AND AT ANY PHASE 0.5. THE TARGET CONSTRAINTS FORM SHOWS ONLY CONSTRAINTS FOR THE PHASE 0.5 OBSERVATION. SIMILAR CONSTRAINTS ARE NEEDED FOR PHASE 0.0.
Epoch: 48832.5000 Period: 15.42200000 Min: 0.4500Max: 0.5500