Nature and spectral variation of B-type emission-line stars with compact dusty envelopes:  HD 85567 and AS 386 Khokhlov Serik

The B[e] Phenomenon Possible explanations for the phenomenon: Discovery: Allen & Swings (1976, A&A, 47, 293) 65 objects with forbidden emission lines and IR excesses at =2 m, due to circumstellar dust Possible explanations for the phenomenon: Formation of a Planetary Nebula (PN) Interaction of an OB star with a cool companion Direct ejection of matter by a massive OB star

FS CMa Type Objects Half of the objects from the initial list of 65 Galactic stars that show the B[e] phenomenon were not identified as members of any group with known evolutionary state. They were called unclassified by Lamers et al. (1998). Miroshnichenko (2007) suggested that most unclassified objects were neither pre-main-sequence Herbig Ae/Be stars nor B[e] supergiants, but rather binary systems and separated them into a new group of FS CMa type objects.

Strong Line Emission Average H EW is an order of magnitude stronger than in Be stars ~100 times higher mass loss rates than typical for dwarf B and Be stars are required to explain these emission-line spectra

Emission-Line Strength Statistical comparison between Be and B[e] stars

Pre-Main-Sequence? A protostellar disk lack of cold dust (inner dust near young stars dissipates first) not associated with known star-forming regions or young clusters, where cold dust could be evaporated by UV radiation from surrounding hot stars

Binarity Signatures: Li 6708

Nature of FS CMa Stars Single stars? Too high mass loss rates for non-luminous objects (>106 Mʘ yr1 for 3−10 Mʘ) Interacting binaries? Can explain the presence of a lot of circumstellar matter! (e.g., models by Wellstein, Langer, & Braun 2001, van Rensbergen 2006, 2008): the gainer cannot take the entire mass, transferred from the donor

Spectral Energy Distribution HD 85567 AS 386 Solid lines – Kurucz model atmospheres for Teff = 15000 K (HD 85567) and 12000 K (AS 386)

HD 85567, V ~ 8.6 mag R.A. 9h50m Dec. −60°58´ 10´ x 10´ field around HD 85567 from the Digital Sky Survey. Optical high-resolution spectroscopy of HD 85567 was obtained at a 1.5 m telescope of CTIO (Chile) with the HIRON spectrograph ( R = 80,000). UBVRI photometry (Johnson-Cousins system) of a 10´ x 10´ field around HD 85567 were obtained at PROMPT robotic telescopes located at CTIO to constrain interstellar extinction near the object.

Fundamental parameters of HD 85567 Interstellar extinction in the direction of HD 85567. Teff relationship with the EW ratio the He I 4713 Å and the Si II 6347 Å lines and EW ratio He I 5875 Å and the Si II 6347 Å lines. Circles represent data for normal B – type stars (filled — OHP, open — TCO). Hertzsprung–Russell diagram showing evolutionary tracks of PMS stars from Tognelli et al. (2011) (thin solid lines) and rotating single stars from Ekstrom et al. (2012) (dashed lines).

Spectral variations of HD 85567 Variations of the Hβ line in the spectrum of HD 85567. Dotted lines show an expected profile of a normal star atmosphere (HR 1149) with Teff ~ 15000 K, log g ~ 4.0, and v sin i ~ 30 kms-1.

Hα line profile of HD 85567 A central peak is observed in some spectra. The heliocentric radial velocity is shown in kms-1, the intensity is normalized to the local continuum.

HD 85567: Conclusions We derived a distance to HD 85567 of 1.3±0.1 kpc, Teff =15000±1000 K (spectral type B4/B5), and an interstellar reddening of E(B - V ) = 0.50±0.02 mag and v sini = 32±5 kms-1. This leads to a luminosity of log L/Lʘ = 3.4±0.1. We found no significant radial velocity variations of the absorption lines in the spectra of HD 85567 obtained during two month-long periods of time in 2012 and 2015 Our analysis of the spectroscopic and photometric data available for the star led us to a conclusion that it cannot be a pre-main-sequence Herbig Ae/Be star. We argue that the circumstellar gas and dust were produced during the object’s evolution as most likely a binary system

AS 386, V ~ 10.9 mag R.A. 20h10m Dec. +38°09´ 8´ x 8´ field around AS 386 from the Digital Sky Survey. Optical high-resolution spectroscopic observations of AS 386 were obtained at McDonald Observatory (Texas, USA, R = 60,000), Observatorio Astronomico Nacional San Pedro Martir (OAN SPM, Baja California, Mexico, R = 18,000) and CFHT (Hawaii, USA, R = 65,000). BVR data in the Johnson-Cousins photometric system of a 8´ x 8´ field around HD 85567 were obtained 1 m telescope of the Tien-Shan Observatory (TSAO) of the Fesenkov Astrophysical Institute (Kazakhstan) and JHK bands were taken at the 1.1 m telescope AZT–24 at Campo Imperatore (Italy) .

Part of a CFHT spectrum of AS 386 Wavelength [Angstroems]

AS 386: Radial Velocity Variations The orbit is circular. Mass function: M2 sin i / (1+q)2 = 1.7 M

AS 386: Components’ Masses

AS 386: Near-IR brightness variations Filled circles – Campo Imperatore, open – 2MASS & Lick Observatory Possible secondary companion – M-star with a hot spot

AS 386: Conclusions The system seems to consist of a ~5 M visible star and an invisible (or much optically fainter) companion with a similar mass. The visible star spectrum is rich with absorption lines that indicate high abundances of such elements as Si, S, N, Ne. The near-IR light curve suggests the presence of several components, including a dusty envelope. Overall, the object is probably an evolved binary after an active mass-transfer phase.