SUMMARY OF PROPOSAL 52010

DR. THOMAS R. AYRES
AYRES@VULCAN.COLORADO.EDU

UNIVERSITY OF COLORADO
CAMPUS BOX 389 (CASA)
BOULDER
CO USA 80309-0389
Tel: 303-492-4051 Fax: 303-492-4052
Medium: 2GB8MM
Subject: STARS

THE CORONA OF THE REMARKABLE HERTZSPRUNG-GAP GIANT HR9024 (G1 III)


ABSTRACT

X-ray coronae of Hertzsprung-gap giants are among the hottest known (log T > 7.2); reminiscent of flares on the Sun, or on classical flare stars. Yet, the F0-G1 giants as a group are not noted for transient UV or X-ray outbursts. The paradox (flare-temperature gas, but lack of overt flaring behavior) bears on the nature of coronal heating at the crucial evolutionary juncture where shallow convective envelopes first emerge; the key transition between hot-star and cool-star X-ray activity. ASCA can add unique insight by directly detecting the hottest coronal gas; short-term variability of the multi-keV X-rays; and anomalous coronal abundances. HR9024 (G1 III), an intriguing transition object within the transition class, is a promising target to continue our program.

CO-INVESTIGATORS
CO-I NAME INSTITUTE COUNTRY
ALEX BROWNU. COLORADO (CASA)USA
STEVE SKINNERU. COLORADO (JILA)USA

TARGETS

TARGET NAMEPRIRADECTIMETCOFFGISSIS CNTOBS
1)HD 223460 (HR 9024)
1
357.4208 36.4253 60 ksN
Y
P
0.75000
1