http://arxiv.org/abs/1802.07743
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 low-ionization broad absorption lines (BALs), most prominently at the Balmer transitions, and as high-ionization BALs from metastable He I*. We report the detection of higher-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 faster 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; exclusively high-ionization BALs have been reported in AS 304 (=V4018 Sgr), while instead 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.
A. Lucy, C. Knigge and J. Sokoloski
Fri, 23 Feb 18
37/64
Comments: submitted to MNRAS; comments welcome; 8 pages, 3 figures, 2 tables, centered on A4 paper [for most 8.5×11 printers, set scaling to None/100% and leave auto-centering on]