Issue |
A&A
Volume 516, June-July 2010
|
|
---|---|---|
Article Number | A24 | |
Number of page(s) | 6 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/200913859 | |
Published online | 22 June 2010 |
SS 433: the accretion disk revealed in Hα
University of Oxford, Department of Physics, Keble Road, Oxford, OX1 3RH, UK
e-mail: m.bowler1@physics.ox.ac.uk
Received:
12
December
2009
Accepted:
17
April
2010
Context. The Galactic microquasar SS 433 is very luminous and ejects opposite jets at approximately one quarter the speed of light. It is regarded as a super-Eddington accretor but until recently there were no observations of accretion.
Aims. We present an analysis of spectroscopic optical data obtained before and during a major flare, which yield in Hα unambiguous evidence for the accretion disk.
Methods. Already published high resolution spectra, taken with a 3.6-m telescope almost nightly over 0.4 of a precession cycle, are analysed.
Results. The spectra, taken almost nightly in August and September 2004,
revealed a period of quiescence followed by activity
which culminated in the
accretion disk of SS 433 becoming visible. The visible material in the
accretion disk orbited the compact object at greater than 500 km
s-1, implying that the mass of the compact object is less than 37 . Evidence that an accretion stream
joins the disk at over 700 km s-1 suggests that the mass is considerably below this upper limit. The accretion disk
clearly orbits the centre of
mass of the binary system with the compact object, sharing its speed of approximately 175 km s-1. The mass of the
companion lies between 20 and 30
and it probably does not fill its Roche lobe.
Key words: stars: binaries: eclipsing / accretion, accretion disks
© ESO, 2010
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