Journal Article

Inflow and outflow from the accretion disc of the microquasar SS 433: UKIRT spectroscopy

Sebastian Perez M. and Katherine M. Blundell

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 397, issue 2, pages 849-856
Published in print August 2009 | ISSN: 0035-8711
Published online July 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14979.x
Inflow and outflow from the accretion disc of the microquasar SS 433: UKIRT spectroscopy

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A succession of near-infrared (near-IR) spectroscopic observations, taken nightly throughout an entire cycle of SS 433's orbit, reveal (i) the persistent signature of SS 433's accretion disc, having a rotation speed of ∼500 km s−1, (ii) the presence of circumbinary disc recently discovered at optical wavelengths by Blundell, Bowler & Schmidtobreick (2008) and (iii) a much faster outflow than has previously been measured for the disc wind, with a terminal velocity of ∼1500 km s−1. The increased wind terminal velocity results in a mass-loss rate of ∼10−4 M yr−1. These, together with the newly (upwardly) determined masses for the components of the SS 433 system, result in an accurate diagnosis of the extent to which SS 433 has super-Eddington flows. Our observations imply that the size of the companion star is comparable with the semiminor axis of the orbit which is given by , where e is the eccentricity. Our relatively spectral resolution at these near-IR wavelengths has enabled us to deconstruct the different components that comprise the Brackett-γ (Brγ) line in this binary system, and their physical origins. With this line being dominated throughout our series of observations by the disc wind, and the accretion disc itself being only a minority (∼15 per cent) contribution, we caution against use of the unresolved Brγ line intensity as an ‘accretion signature’ in X-ray binaries or microquasars in any quantitative way.

Keywords: accretion, accretion discs; binaries: spectroscopic; stars: individual: SS 433; stars: winds, outflows

Journal Article.  5664 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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