Cw. Ambruster et al., THE EXTREMELY ACTIVE SINGLE GIANT 1E-1751- REVISED PROPERTIES AND A REEVALUATION OF ITS EVOLUTIONARY STATUS(7046 EQUALS ET DRACONIS ), The Astrophysical journal, 479(2), 1997, pp. 960-969
New spectroscopic observations have resulted in significant revisions
to several of the orginally published properties of the X-ray bright,
chromospherically active star 1E 1751+7046: the spectral classificatio
n has been revised from K5 IV to K0 III, v sin i from 30-40 km s(-1) t
o 23 km s(-1), and the reported nondetection of the Li I 6707 Angstrom
line to a significant log epsilon(Li) = 1.8. Chromospheric and transi
tion region surface fluxes from IUE observations and the coronal surfa
ce flux from earlier Einstein data are close to saturation levels, and
comparable only to very active binaries, pre-main-sequence stars, and
FK Comae itself. IUE observations also recorded a flare. Fifteen new
radial velocity measurements show no evidence for a companion and are
consistent with intermediate or young disk membership. On the other ha
nd, we show the star to be located about 250 pc above the galactic pla
ne, suggesting an intermediate or old disk object. The new spectral cl
ass (T-eff) and limits on the luminosity indicate that 1E 1751 + 7046
is a low-mass star on its first ascent of the giant branch. Photometry
from the Four College Consortium Automatic Photometry Telescope is co
nsistent with the recently published photometric period of 13.98 days,
and the light curve is well fitted by a model consisting of two large
spots at latitudes of similar to 30 degrees and similar to 50 degrees
. There are currently only two possible evolutionary scenarios for thi
s anomalous star: (a) coalescence from a progenitor W UMa-type contact
binary; or (b) the dredge-up of both angular momentum and nuclear pro
cessed material in a low-mass (similar to 1-2.5 M-.) giant. A space mo
tion, obtainable once a parallax and proper motion are available from
Hipparcos, may resolve the age (old disk-young disk) uncertainty: youn
g disk motions would favor the angular momentum transfer scenario. The
re is no current theory that can account for the observed lithium abun
dance.