![]() Thus if emission lines are formed in the shell after the time of detachment, the mean Doppler shift of the shell spectrum will reflect the velocity vector of the source at the time of detachment rather than at the time of formation of the emission lines. If the very luminous source is a member of a binary system, the trajectory of the centre of a shell of wind does not deviate as the star continues in its closed orbit. When close to the terminal velocity that expanding shell is effectively detached from the star and thereafter continues to expand with its centre following a straight-line trajectory, the velocity vector of which is equal to the velocity vector of the source at the time of detachment. It is accelerated rapidly to the terminal velocity, perhaps several thousand km s -1. We consider a very luminous star blowing a dense wind and a particular shell within that wind. Key words: binaries: close / stars: fundamental parameters / stars: winds, outflows The characteristic lifetime of H α emitting material is a few days, as observed for the relativistic bolides in the jets. Their properties are entirely consistent with an origin in a circumbinary disk. ![]() The broad component is undoubtedly formed in the wind from the accretion disk and the two narrow components carry no such signature. The structure of the stationary H α emission line is now well understood. It is also close to the timescales observed for the individual bolides that radiate H α in the relativistic jets.Ĭonclusions. This timescale is very close to what is required for the decay of H α from the putative circumbinary disk to be responsible for the narrow components of the H α emission line. If the decay is exponential, a mean lifetime of about two days is all that is required. The loss of memory by emission lines from the wind is easily understood quantitatively, if any parcel of wind that has been newly conditioned to radiate in H α continues its emission for a period of days. We analysed stationary H α spectra, taken almost nightly over two orbital periods of the binary system. The aim is to understand how this emission line is left with a blurred memory of the motion of the source of the wind. ![]() The centroid of the H α emission line formed in the wind has an imperfect memory of the motion of its source.Īims. This is formed in the wind blowing from the accretion disk of the compact object, which orbits the centre of mass of the binary at ~175 km s -1 with a 13-day period. The brilliant Balmer H α line in the stationary emission spectrum of the Galactic microquasar SS 433 has a broad component (~1000 km s -1). University of OxfordDepartment of Physics,Ĭontext.
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