On the nature of the Herbig Be star V 380 Orionis ^*,**

¹ Istituto Astronomico, Università La Sapienza, Via G.M. Lancisi 29, 00161 Roma, Italy
² Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italia
³ Institut d'Astrophysique, CNRS, 98bis Boulevard Arago, 75014 Paris, France
⁴ Istituto di Astrofisica Spaziale, CNR, Area di Ricerca Tor Vergata, Via del Fosso del Cavaliere, 00133 Roma, Italy
⁵ Observatoire de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 04, France

Send offprint request to: C. Rossi

Received: 11 August 1997
Accepted: 16 December 1998

Abstract

We discuss new and archive spectroscopic and photometric observations of the Herbig Ae star V 380 Ori obtained between 1978 and 1995 and covering at different epochs the wavelength range from 1200 Å to 5 μm. The coordinated JHKLM and CVF infrared observations and optical spectroscopy made at ESO of March 1985 confirm the presence of a strong IR excess due to emission from hot cicumstellar dust. The comparison with IR photometry from the literature suggests the presence of oscillations, without secular variations. The optical spectrum of V 380 Ori, observed at ESO during 1983–1985, and at OHP in January 1995, remained substatially stable, and was all the time characterized by a large number of broad ( km s^-1) permitted emission lines, probably formed in a rotating optically thick disk. The strongest Fe ii  lines have complex profile with a principal central emission and a blue–shifted (-140 km s^-1) wind component, the redward component probably being occulted by the disk. The multiplet 42 lines have P Cygni absorption components shifted by -250 km s^-1 which should be associated with a teneous cool wind. We remark the secular behaviour of the stellar activity probe He i 5876 Å line, which is present in all our spectra as a broad emission, while in other times it was absent or in absorption. The ultraviolet (IUE) spectrum shows a short wavelength cut off at  Å typical of a B9–A0 star, with a rich absorption spectrum, which is thought to be produced in an optically thick stellar envelope or wind. The 2175 Å interstellar band strength is consistent with a mean galactic–type extinction law with an , much smaller than that derived from the visual (~0.5), which suggests an anomalous local UV extinction. The comparison of the archive IUE data shows that during 1978–1989 there was no significant flux variation, with the possible exception of the UV Mg ii emission line.