A&A Supplement series, Vol. 129, May I 1998, 541-552
Received September 5; accepted October 27, 1997
R.D. Oudmaijer
Send offprint request: R.D. Oudmaijer e-mail: r.oudmaijer@ic.ac.uk
Imperial College of Science, Technology and Medicine,
Blackett Laboratory, Prince Consort Road, London, SW7 2BZ, UK
Kapteyn Astronomical Institute, P.O. Box 800, NL-9700 AV Groningen, The
Netherlands
A high resolution optical spectrum of the post-red supergiant candidate
IRC+10420 is presented. The Utrecht Echelle Spectrograph observations, with
a total integration time of more than 9 hours, provide a spectral coverage
from 3850 Å to 1 
m, and a spectral resolution of 9 km s-1. The
spectrum is shown, and an identification list of lines in the spectrum
is provided. From a preliminary analysis of the spectrum we find that
the spectral type of IRC+10420 has changed from F8I+ in 1973 to mid- to
early A type now, confirming the results of Oudmaijer et al.\
(1996), who claimed a change in temperature based on photometric
changes. It is shown that most of the emission lines in the spectrum of
IRC+10420 are blue-shifted with respect to the systemic velocity traced by
circumstellar rotational CO emission, while the (few)
absorption lines - with the exception of some high excitation lines -
are red-shifted by 25 km s-1, which may suggest infall of material onto the
star. Finally, it is found that the interstellar extinction towards
IRC+10420 as traced by the Diffuse Interstellar Bands is very large, with an
inferred E(B-V) of 1.4 
0.5 compared to a total E(B-V) of 2.4.
keywords: stars: circumstellar matter -- stars: emission-line, Be -- stars: individual: IRC+10420 -- stars: AGB and post-AGB -- stars: supergiants