Spectroscopy of the MAXI J1836-194 Optical Counterpart: Likely Be X-ray Binary
ATel #3614; S. B. Cenko, A. A. Miller, and J. S. Bloom (UC Berkeley) report on behalf of a larger collaboration:
on 31 Aug 2011; 07:32 UT
Credential Certification: S. Bradley Cenko (cenko@astro.berkeley.edu)
Subjects: Optical, Binary, Black Hole, Neutron Star, Star, Transient
We obtained a low resolution spectrum of the optical counterpart (ATEL #3613) of the recently discovered high-energy transient source MAXI J1836-194 (ATEL #3611) with the Gemini Multi-Object Spectrograph mounted on the 8 m Gemini South telescope. Observations began at 2:58 UT on 2011 August 31 and cover the wavelength range from 4000-10000 A.
The spectra exhibit broad, weak Balmer absorption, together with super-imposed narrow Balmer emission lines, all consistent with their rest frame wavelengths. By comparing these and additional absorption features with a stellar spectral atlas, we infer a spectral type of ~ Be, consistent with the blue colors inferred from the UVOT photometry (ATEL #3613). We therefore consider it likely that MAXI J1836-194 is an outburst from a Be (high-mass) X-ray binary.
We wish to thank the entire Gemini staff, in particular Ruben Diaz, for the prompt execution of these observations.
