2024MNRAS.528..122S -
Mon. Not. R. Astron. Soc., 528, 122-140 (2024/February-2)
Multitechnique study of the B[e] supergiant RMC 82.
SERIACOPI D.B., CARCIOFI A.C., DE AMORIM T.H., MAGALHAES A.M., VIEIRA R.G., DOMICIANO DE SOUZA A., RUBIO A., RUBINHO M.S., BEDNARSKI D., MOTA B.C., FAES D.M. and SILVA A.C.F.
Abstract (from CDS):
B[e] supergiants (sgB[e]) are rare objects whose evolutionary stage remains uncertain. Observationally, they display strong Balmer emission lines, infrared excess, and intrinsic polarization, indicating a non-spherical circumstellar envelope. We present a study of the sgB[e] RMC 82, using new spectropolarimetric data complemented by photometry from the ultraviolet (UV) to the mid-infrared. Our two-component model comprises a slow, dense equatorial wind wherein dust grains form and a fast polar wind. We applied the hdust radiative transfer code and Bayesian statistics to infer the parameters from a grid of 3240 pre-computed models. The model accurately reproduces the spectral energy distribution and polarized spectrum, but struggles to match the H α emission. Our results suggest a large mass-loss rate of $6.6 \times 10^{-6}\, \mathrm{{\rm M}_{\odot }\, yr^{-1}\, sr^{-1}}$. The dense wind is confined within an opening angle of 11°. The hottest dust grains are located at 277 R* with a temperature of 870 K. The dust grains are porous, with a density of 0.051 $\rm {g\, cm^{-3}}$. The central star was found to be significantly hotter than previous estimates (Teff = $27\, 000$ K). By comparing models with different components, we find that gas reprocesses a significant amount of UV radiation, shielding the dust. However, the dust also scatters UV photons back to the inner disc, increasing its temperature and H α emission. We conclude that self-consistent models, that account for the gas-dust interplay in the envelope, are essential for studying sgB[e] and similar objects.
Abstract Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
Journal keyword(s):
polarization - radiative transfer - scattering - circumstellar matter - supergiants - stars: winds, outflows
Simbad objects:
6
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