A Precessing Jet in the CH Cyg Symbiotic System

Jets have been detected in only a few symbiotic binaries to date, and CH Cyg is one of them. In 2001, a non-relativistic jet was detected in CH Cyg for the first time in X-rays. We carried out coordinated Chandra, HST, and VLA observations in 2008 to study the propagation of this jet and its interaction with the circumbinary medium. We detected the jet with Chandra and HST and determined that the apex has expanded to the South from about 300 AU to about 1400 AU, with the shock front propagating with velocity < 100 km/s. The shock front has significantly slowed down since 2001. Unexpectedly, we also discovered a powerful jet in the NE-SW direction, in the X-ray, optical and radio. This jet has a multi-component structure, including an inner jet and a counter-jet at about 170 AU, and a SW component ending in several clumps extending out to approximately 750 AU. The structure of the jet and the curvature of the outer portion of the SW jet suggest an episodically powered precessing jet, or a continuous precessing jet with occasional mass ejections or pulses. We carried out detailed spatial mapping of the X-ray emission and correlation with the optical and radio emission. X-ray spectra were extracted of the central source, inner NE counter jet, and the brightest clump at a distance of approximately 500 AU from the central source. We discuss the initial results of our analyses, including the multi-component spectral fitting of the jet-components and of the central source.

💡 Research Summary

The symbiotic binary CH Cygni is one of the few systems in which jets have been directly observed, and it provides a rare laboratory for studying jet–environment interactions in a non‑relativistic context. After the first X‑ray detection of a south‑ward jet in 2001, the authors performed a coordinated multi‑wavelength campaign in 2008 using the Chandra X‑ray Observatory, the Hubble Space Telescope (HST), and the Very Large Array (VLA). The south‑ward jet, originally located at ~300 AU from the central binary, had expanded to ~1,400 AU by 2008, but its shock front velocity had dropped to less than 100 km s⁻¹, indicating substantial deceleration as the jet ploughed into the dense circumbinary medium. In addition to this “old” jet, the authors discovered a previously unknown NE–SW jet that is visible in X‑ray, optical emission lines (e.g., Hα,