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arXiv · 1803.03892

Toward Understanding the B[e] Phenomenon. VII. AS 386, a single-lined binary with a candidate black hole component

S. A. Khokhlov·A. S. Miroshnichenko·S. V. Zharikov·N. Manset·A. A. Arkharov·N. Efimova·S. Klimanov·V M. Larionov·A. V. Kusakin·R. I. Kokumbaeva·Ch. T. Omarov·K. S. Kuratov·A. K. Kuratova·R. J. Rudy·E. A. Laag·K. B. Crawford·T. K. Swift·R. C. Puetter·R. B. Perry·S. D. Chojnowski·A. Agishev·D. B. Caton·R. L. Hawkins·A. B. Smith·D. E. Reichart·V. V. Kouprianov·J. B. Haislip
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Abstract

We report the results of spectroscopic and photometric observations of the emission-line object AS 386. For the first time, we found that it exhibits the B[e] phenomenon and fits the definition of an FS CMa type object. The optical spectrum shows the presence of a B-type star with the following properties: T_ eff = 11000+/-500 K, log L/L_sun = 3.7+/-0.3, a mass of 7+/-1 M_sun, and a distance D = 2.4+/-0.3 kpc from the Sun. We detected regular radial velocity variations of both absorption and emission lines with the following orbital parameters: P_orb = 131.27+/-0.09 days, semi-amplitude K_1 = 51.7+/-3.0 km/s, systemic radial velocity gamma = -31.8+/-2.6 km/s, and a mass function of f(m) = 1.9+/-0.3 M_sun. AS 386 exhibits irregular variations of the optical brightness (V=10.92+/-0.05 mag), while the near-IR brightness varies up to ~0.3 mag following the spectroscopic period. We explain this behavior by a variable illumination of the dusty disk inner rim by the B-type component. Doppler tomography based on the orbital variations of emission-line profiles shows that the material is distributed near the B-type component and in a circumbinary disk. We conclude that the system has undergone a strong mass transfer that created the circumstellar material and increased the B-type component mass. The absence of any traces of a secondary component, whose mass should be >= 7 M_sun, suggests that it is most likely a black hole.

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S. A. Khokhlov, A. S. Miroshnichenko, S. V. Zharikov, N. Manset, A. A. Arkharov, N. Efimova, S. Klimanov, V M. Larionov, A. V. Kusakin, R. I. Kokumbaeva, Ch. T. Omarov, K. S. Kuratov, A. K. Kuratova, R. J. Rudy, E. A. Laag, K. B. Crawford, T. K. Swift, R. C. Puetter, R. B. Perry, S. D. Chojnowski, A. Agishev, D. B. Caton, R. L. Hawkins, A. B. Smith, D. E. Reichart, V. V. Kouprianov, J. B. Haislip. 2018-03-13. Toward Understanding the B[e] Phenomenon. VII. AS 386, a single-lined binary with a candidate black hole component. https://doi.org/10.3847/1538-4357%2Faab49d

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