Large-scale variability in the profiles of Hα and Hβ in the spectrum of the Herbig B8e star MWC 419 and a model interpretation of it

Abstract

Spectroscopic data taken with a moderate resolution spectrograph in the region of the Hα and Hβ lines are presented for the Herbig B8e star MWC 419. The spectroscopic observations were accompanied by broad band BVR photometric measurements. The observations reveal a variability in the line profiles that is typical of Herbig Ae/Be stars with signs of a strong stellar wind. The greatest changes are observed in the region of the absorption components of the line profiles, which convert the profile from a type P CygII to P CygIII, as well as in the intensities of the central emission components. A model technique is used for quantitative interpretation of this variability and it shows that the P Cyg profile conversion of the absorption component can be explained in terms of a stellar wind model in which its distribution over latitude varies on a time scale of a few days.

FIRSTL-BAND INTERFEROMETRIC OBSERVATIONS OF A YOUNG STELLAR OBJECT: PROBING THE CIRCUMSTELLAR ENVIRONMENT OF MWC 419

“…As discussed earlier (Section 3.2), the accretion disk model requires an unrealistically large accretion rate, on the order of a few times 10 −5 M ⊙ yr −1 in order to fit the SED data. Simple estimates of the accretion rate for this star range from 5×10 −7 to 10 −6 M ⊙ yr −1 based on mass loss data and upper limits to radio emission at 3.6 cm (Kurchakov et al 2007;Boehm & Catala 1995;Skinner et al 1993). The necessity of an unrealistically large accretion rate in the accretion disk model is probably an artifact of the physically unrealistic assumption of a zero-thickness disk which causes the re-processing of radiation to be very inefficient.…”