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On the binary nature of 1RXS J162848.1-415241

M. A. P. Torres·M. R. Garcia·D. Steeghs·J. E. McClintock
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Abstract

We present spectroscopy of the optical counterpart to 1RXS J162848.1-41524, also known as the microquasar candidate MCQC J162847-4152. All the data indicate that this X-ray source is not a microquasar, and that it is a single-lined chromospherically active binary system with a likely orbital period of 4.9 days. Our analysis supports a K3IV spectral classification for the star, which is dominant at optical wavelengths. The unseen binary component is most likely a late-type (K7-M) dwarf or a white dwarf. Using the high resolution spectra we have measured the K3 star's rotational broadening to be vsini = 43 +/- 3 km/s and determined a lower limit to the binary mass ratio of q(=M2/M1)>2.0. The high rotational broadening together with the strong CaII H & K / Halpha emission and high-amplitude photometric variations indicate that the evolved star is very chromospherically active and responsible for the X-ray/radio emission.

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M. A. P. Torres, M. R. Garcia, D. Steeghs, J. E. McClintock. 2005-06-18. On the binary nature of 1RXS J162848.1-415241. https://doi.org/10.1086/432907

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