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.