Neutral material around the B[e] supergiant star LHA 115-S 65: An outflowing disk or a detached Keplerian rotating disk?

Abstract

B[e] supergiants are surrounded by large amounts of hydrogen neutral material, traced by the emission in the optical [OI] lines. This neutral material is most plausibly located within their dense, cool circumstellar disks, which are formed from the (probably non-spherically symmetric) wind material released by the star. Neither the formation mechanism nor the resulting structure and internal kinematics of these disks (or disk-like outflows) are well known. However, rapid rotation, lifting the material from the equatorial surface region, seems to play a fundamental role. The B[e] supergiant LHA 115-S 65 (S65) in the SMC is one of the two most rapidly rotating B[e] stars known. Its almost edge-on orientation allows a detailed kinematical study of its optically thin forbidden emission lines. With a focus on the [OI] lines, we test the two plausible disk scenarios: the outflowing and the Keplerian rotating disk. Based on high- and low-resolution optical spectra, we investigate the density and temperature structure in those disk regions that are traced by the [OI] emission to constrain the disk sizes and mass fluxes needed to explain the observed [OI] line luminosities. In addition, we compute the emerging line profiles expected for either an outflowing disk or a Keplerian rotating disk, which can directly be compared to the observed profiles. Both disk scenarios deliver reasonably good fits to the line luminosities and profiles of the [OI] lines. Nevertheless, the Keplerian disk model seems to be the more realistic one, because it also agrees with the kinematics derived from the large number of additional lines in the spectrum. As additional support for the presence of a high-density, gaseous disk, the spectrum shows two very intense and clearly double-peaked [CaII] lines. We discuss a possible disk-formation mechanism, and similarities between S65 and the group of LBVs.

arXiv comment13 pages, 12 figures, accepted for publication in A&A

References in corpus (15)

• Stellar evolution with rotation XI: Wolf-Rayet star populations at different metallicities
• Be-star rotation: how close to critical?
• Bump Cepheids in the Magellanic Clouds: Metallicities, the Distances to the LMC and SMC, and the Pulsation-Evolution Mass Discrepancy
• Viscous Transonic Decretion in Disks of Be Stars
• B-type Supergiants in the SMC: Chemical compositions and comparison of static and unified models
• The influence of rotation in radiation driven wind from hot stars: New solutions and disk formation in Be stars
• Bona-fide, strong-variable galactic Luminous Blue Variable stars are fast rotators: detection of a high rotational velocity in HR Carinae
• On the Structure and Kinematics of Nebulae around LBVs and LBV Candidates in the LMC
• Outflowing disk formation in B[e] supergiants due to rotation and bi--stability in radiation driven winds
• On the optical--infra-red continuum emission from equatorial discs of supergiant B[e] stars
• S 111 and the polarization of the B[e] supergiants in the Magellanic Clouds
• From B[e] to A[e]. On the peculiar variations of the SMC supergiant LHA 115-S 23 (AzV 172)
• Accretion-Induced Collimated Fast Wind Model for Eta Carinae
• Ionization structure in the winds of B[e] supergiants: I. Ionization equilibrium calculations in a H plus He wind
• Ionization structure in the winds of B[e] supergiants II. Influence of rotation on the formation of equatorial hydrogen neutral zones

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