Radio-emitting component kinematics in SS433

• Published in: Monthly notices of the Royal Astronomical Society Vol. 337; no. 2; pp. 657 - 665
• Main Authors: Stirling, A. M., Jowett, F. H., Spencer, R. E., Paragi, Z., Ogley, R. N., Cawthorne, T. V.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.12.2002
• Subjects: ISM: jets and outflows; radio continuum: stars; stars: individual: SS433; stars: individual: SS433; ISM: jets and outflows; radio continuum: stars
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1046/j.1365-8711.2002.05944.x

SS433 is a galactic X-ray binary source, variable across most wavelengths of observation. On arcsecond-scales the radio emission is composed of a bright core and the famous bipolar ‘corkscrew’ radio jets. A series of MERLIN observations at 5 GHz were taken in 1991 December and 1992 January. The emission from the radio jet was categorized by replacing discrete features with Gaussian flux-density profiles. These fitted components were used to derive proper motions, ejection position-angles and ejection dates for evolving features in the jets. The observed component position-angles and ejection dates were compared to those predicted by the kinematic model of epoch 1989. The position-angle of the precession cone was refined to 98.°2±0.°2. A discrepancy was discovered in the observed precessional phase which was leading that of the kinematic model by 7–10 d. This observed discrepancy was in agreement with a transient deviation in precessional phase as measured by the redshifts of optical bullets at a similar time. Analysis of the proper motions of all the fitted components leads to a distance measurement of 4.61 ± 0.35 pc. A pair of symmetrically ejected knots with a velocity much lower than 0.26cwere also discovered. Their ejection time overlapped with a period of unusual Doppler shift residuals and fragmentation of optical bullets. These events may represent the first evidence for an interaction between radio components and optical bullets.