Astron. Astrophys. 322, 511-522 (1997)
Our main results can be summarized as follows:
- The photometric period of IN Comae is 5.913
0.005 days and not 1.2 days as claimed by
several earlier studies. We interpret it as the rotation period of
- The spectral classification is G5 0.5III-IV
(maybe III- but not IV) in agreement with its minimum radius of 7.8
0.2 and an effective
temperature of 5200 60 K. An inclination of
is therefore most likely.
- Our three Doppler images from March 1994 reveal mostly
low-latitude spots with a temperature of 4700
50 (rms) K. Only the Fe I -6411 line shows a
small, asymmetric polar spot of similar temperature.
- Surprisingly, some of the cool features from the strong calcium
line show up at significantly lower latitudes than in the weaker
iron-line maps. We tentatively suggest that we actually map an
optical-depth dependence of the flux ratio between spots and
- We detect "interstellar" absorption lines in the NaD spectrum of
IN Comae but suggest that their origin may be due to the
planetary nebula and not to interstellar absorption since the star is
located very close to the galactic north pole where no significant
interstellar reddening is obvious (in agreement with a recent study of
interstellar hydrogen towards the north galactic pole by Piskunov et
- From the width of the Ca II -K line, the
Wilson-Bappu relation gives a distance of about 700 pc.
- There is no detectable Li I 6707-Å line
indicating that IN Comae is an old star that had enough time to
deplete its surface lithium, which in turn is in agreement with its
location within the planetary nebulae LoTr-5.
© European Southern Observatory (ESO) 1997
Online publication: June 5, 1998