SUMMARY OF PROPOSAL 42003
DR. THOMAS R. AYRES
UNIVERSITY OF COLORADO
CO USA 80309-0389
BOULDER
CAMPUS BOX 389 (CASA)

  E-mail: AYRES@VULCAN.COLORADO.EDU	Tel: 303-492-4051	Fax: 303-492-7178
  Medium: 2GB8MM

Subject: STARS                                                       
  Title: HERTZSPRUNG-GAP CORONAE: HOW HOT AND VARIABLE?                                  


Abstract:
 The X-ray coronae of Hertzsprung-gap giants are among the hottest known (log T >
 7.3); reminiscent of flaring gas in solar active regions, or on RS CVn binaries and
 dMe stars. Yet, the F0-G1 giants as a class are not noted for transient UV or X-ray
 outbursts. The paradox (flare-temperature plasma, 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 highest excitation coronal gas; possible short-term variability of the
 multi-keV X-rays; and anomalies in the coronal abundances. 31 Comae (G0 III),
 well-studied at other wavelengths, is the most promising target.

 Co-Is:
   1  STEVE SKINNER       	U. COLORADO (JILA)            USA       
      (No Co-I contact data)
   2  ALEX BROWN          	U. COLORADO (CASA)            USA       


Target Name           PRI RA        Dec        Time TC  Off GIS SIS_Cts  Obs
-------------------   --- --------  --------   ---- --  --- --- -------  ---
HD 111812 (31 COM)     0  192.9250   27.5406    40   N   Y   P  0.58000   1