SS 433: Distance Determination with Radio Images
Jared H. Crossley
14 May 2003
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Outline
• Introduction: SS 433 and W 50• Research question and thesis• The kinematic model of SS 433• Findings
– Jet deceleration
– Velocity-distance degeneracy
• Conclusions• Study limitations and future work
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Introduction
• SS 433 was discovered in late 1970’s, very complex optical emission
• Lies at the center of supernova remnant
W 50Dubner, et al. (1998)
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Intro continued…
• One of the brightest X-ray binaries; only one with persistent evolving large scale radio jets
• A kinematic model of jet structure was developed and revised over the past 20+ years
http://www.astro.soton.ac.uk/~rih/
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Research Question• Emission from W 50 places the system at a
distance of 3 kiloparsecs (1 parsec = 3.3 light-years)
• Fitting models of SS 433 to observed data results in a distance of 5 kpc.
• I show that the model-fitting method may be flawed, by providing evidence of – Jet deceleration, not accounted for – A velocity-distance degeracy
Thesis
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Model Parameters1. P – precession period
2. t0 – time where precession phase is zero
3. v – speed of matter in beams
4. i – inclination of precession cone axis
5. θ – half opening angle of cone
6. D – distance to object 7. χ – position angle of
cone axis8. s – handedness of
precession9. δ – declination
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
8.5 GHz VLA
16 Dec 1996
8.5 GHz VLA
13 Jan 1997
1.5 GHz VLBA
6 Mar 1998
15 GHz VLA
5 Mar 1998
Jet Deceleration D = 4.8, 5, and 5.2 kpc
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
8.5 GHz VLA
16 Dec 1996
8.5 GHz VLA
13 Jan 1997
15 GHz VLA
5 Mar 1998
1.5 GHz VLBA
6 Mar 1998
Velocity-Distance Degeneracy v/c = 0.2647, D = 5 kpcv/c = 0.15 , D = 3 kpc
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Conclusions
• Evidence of jet deceleration with distance from the core
• Velocity-distance degeneracy exists in the model
• Distances obtained from spatial modeling of jet structure must be re-evaluated
14 May 2003 SS 433: Distance Determination with Radio Images
Jared Crossley
Limitations & Future Work
• This study was limited by using only four epochs of observations
• Further corroboration of the above results should employ a larger number of epochs, distributed evenly in jet phase
Thanks to Michael Rupen, Vivek Dhawan, and Amy Mioduszewski (NRAO) for their help with this project.