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Paper: The Spectroscopic Variability of the Herbig Be Star HD 259431
Volume: 518, Physics of Magnetic Stars
Page: 138
Authors: Pogodin, M. A.; Pavlovskiy, S. ..; Drake, N. A.; Beskrovnaya, N. G.; Kozlova, O. V.; Alekseev, I. Y.; Fernandes, M. B.; Pereira, C. B.; Valyavin, G. G.; Miroshnichenko, A. S.; Gorda, S. Y.
Abstract: High-resolution spectra of the Herbig Be star HD 259431 obtained in 2010–2018 at four observatories (Crimean AO, ESO in Chile, OAN SPN in Mexico, and the Kourovka Observatory of Ural Federal University) are analyzed. The star demonstrates a spectrum rich in emission lines. The bulk of the lines exhibit double emission profiles and originate in the gaseous disk. The atmospheric lines are unusually shallow, and the majority of them are distorted by the circumstellar (CS) contribution. Previously, we have revealed that they are overlapped with an additional continuum emission. Using the observed ratio of the equivalent widths of the two He I lines at λ4009 and λ4026, we estimated the spectral type of the object as B5 V. We have also revealed that the additional continuum corresponds to the blue part of the black body spectrum. The Balmer emission lines Hβ –Hε show very variable profiles looking as either of the P Cyg type or a double-peaked emission line with a depression of the red wing. We found the period of this variability P = 2.84d and interpreted it as a signature of a rotating magnetosphere of the star with the magnetic axis inclined to the rotation axis. At different phases of rotation the observer can see either the accretion flow at high magnetic latitudes or the wind zone at lower latitudes. We estimated the inclination of the rotation axis i = 43° ± 3°.
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