Broad absorption line symbiotic stars: highly ionized species in the fast outflow from MWC 560

Abstract

In symbiotic binaries, jets and disk winds may be integral to the physics of accretion onto white dwarfs from cool giants. The persistent outflow from symbiotic star MWC 560 (=V694 Mon) is known to manifest as broad absorption lines (BALs), most prominently at the Balmer transitions. We report the detection of high-ionization BALs from C IV, Si IV, N V, and He II in International Ultraviolet Explorer spectra obtained on 1990 April 29-30, when an optical outburst temporarily erased the obscuring 'iron curtain' of absorption troughs from Fe II and similar ions. The C IV and Si IV BALs reached maximum radial velocities at least 1000 km/s higher than contemporaneous Mg II and He II BALs; the same behaviors occur in the winds of quasars and cataclysmic variables. An iron curtain lifts to unveil high-ionization BALs during the P Cygni phase observed in some novae, suggesting by analogy a temporary switch in MWC 560 from persistent outflow to discrete mass ejection. At least three more symbiotic stars exhibit broad absorption with blue edges faster than 1500 km/s; high-ionization BALs have been reported in AS 304 (=V4018 Sgr), while transient Balmer BALs have been reported in Z And and CH Cyg. These BAL-producing fast outflows can have wider opening angles than has been previously supposed. BAL symbiotics are short-timescale laboratories for their giga-scale analogs, broad absorption line quasars (BALQSOs), which display a similarly wide range of ionization states in their winds.

Accepted to MNRAS (v2: minor expository revisions); 8 pages, 3 figures, 2 tables, centered on A4 paper [for most 8.5x11 printers, set scaling to None/100% and leave auto-centering on]

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Cited by in corpus (4)

• Regulation of accretion by its outflow in a symbiotic star: the 2016 outflow fast state of MWC 560
• Long-term X-ray Variability of the Symbiotic System RT Cru based on Chandra Spectroscopy
• X-ray Variability in the Symbiotic Binary RT Cru: Principal Component Analysis
• Flickering of the jet-ejecting symbiotic star MWC 560