New Herbig Ae/Be stars confirmed via high-resolution optical spectroscopy

Abstract

We present FEROS high-resolution (R ∼ 45 000) optical spectroscopy of 34 Herbig Ae/Be star candidates with previously unknown or poorly constrained spectral types. Within the sample, 16 sources are positionally coincident with nearby (d < 250 pc) star-forming regions (SFRs). All the candidates have reported infrared excess. We determine the spectral type and luminosity class of the sources, derive their radial and projected rotational velocities, and constrain their distances employing spectroscopic parallaxes and photometry from the literature. We confirm 13 sources as Herbig Ae/Be stars and find one classical T Tauri star. Three sources are emission line early-type giants (B, A, and F stars with luminosity class III) and may be Herbig Ae/Be stars. One source is a main-sequence Atype star. Fourteen sources are post-main-sequence giant and supergiant stars (7 with Hα emission and 7 without). Two sources are extreme emission-line stars and no accurate spectral classification was possible because of strong veiling. Most of the sources appear to be background stars at distances over 700 pc. We show that high-resolution optical spectroscopy is a crucial tool for distinguishing young stars (in particular Herbig Be stars) from post-main sequence stars in samples taken from emission-line star catalogs based on low-resolution spectroscopy. Within the sample, three young stars (CD-38 4380, Hen 3-1145, and HD 145718) and one early-type luminosity class III giant with emission lines (Hen 3-416) are at distances closer than 300 pc and are positionally coincident with a nearby SFR. These 4 sources are likely to be nearby young stars and are interesting for follow-up observations at high-angular resolution. Furthermore, seven confirmed Herbig Ae/Be stars at d > 700 pc (Hen 2-80, Hen 3-1121 N&S, HD 313571, MWC 953, WRAY 15-1435, and Th 17-35) are inside or close (<5 ) to regions with extended 8 μm continuum emission and in their 20 vicinity have astronomical sources characteristic of SFRs (e.g., HII regions, molecular clouds, dark nebulae, masers, young stellar-objects). These 7 sources are likely to be members of SFRs.

Spitzerobservations of a circumstellar nebula around the candidate luminous blue variable MWC 930

“…These values rule out a post-AGB classification and make the star a candidate LBV. Subsequent studies confirmed the spectral classification as a B5-B9 star with emission lines that show P Cyg profiles (Carmona et al 2010) and Brackett emission lines in the near-IR without detectable CO bands (Venkata Raman & Anandarao 2008).…”

Keplerobservations of A–F pre-main-sequence stars in Upper Scorpius: discovery of six new δ Scuti and one γ Doradus stars

“…• EPIC 204399980 (HIP 79476 = HD 145718) has been studied spectroscopically in some detail by Carmona et al (2010). The spectrum displays an inverse P Cygni Hα profile, presumably a result of accretion, confirming the Herbig Ae nature of this star.…”

“…On this basis we believe that our estimate of T spec eff =8100±300 K is sound. In passing, we note that our CAOS spectrum allows us to evaluate the possible multiplicity of EPIC 204399980, by comparing our determination of V rad =−7.4±6.4 km s −1 with Carmona et al (2010)'s V rad =0±3 km s −1 . The two values agree within ∼ 1 σ, hence we conclude that at least with present data, there is no evidence of multiplicity for this star.…”

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

“…Where an appropriate synthetic spectrum was not available, we used a synthetic spectrum of similar spectral type as the star observed. For this purpose we used the interactive IDL-based software described in Carmona et al (2010). This tool allows the synthetic and target spectra to be displayed, and to calculate the radial velocity of the observed spectrum using the cross-correlation technique.…”