Bipolar Jets and Orbital Dynamics of the Supersoft X‐Ray Source RX J0019.8+2156

Abstract

Between 1994 July and 1997 February we monitored the optical spectrum of RX J0019.8]2156. This supersoft X-ray source is one of only two accreting white dwarfs in the Galaxy that are thought to be burning hydrogen on their surface as a consequence of a high rate of mass transfer from a binary companion. Accurate orbital ephemerides are derived from radial velocity measurements for the white dwarf, which are obtained from strong He II emission lines with a stable velocity semiamplitude of K \ 71.2^3.6 km s~1. We report the discovery of transient, low-velocity, bipolar jets. These jets are represented by redshifted-blueshifted pairs of emission lines from H and He II with an outÑow velocity of v cos (i) D 815 km s~1, where i is the binary inclination angle. When present, the jet lines seen in Ha also exhibit an orbital modulation of 71 km s~1, which strengthens the interpretation that this is the orbital velocity of the white dwarf and also indicates that the jets are oriented nearly perpendicular to the orbital plane. On most occasions, the H emission line proÐles are further altered by P Cygni absorption e †ects, and the strength of this absorption is also dependent on binary phase. We show that the jets and the P Cygni features have very di †erent temporal characteristics and binary phase dependence ; thus, we conclude that the outÑowing material and the absorbing wind must have essentially di †erent geometries. Finally, the measured mass function is combined with binary evolution models to suggest a limit on the inclination angle, i \ 40¡. A particular model invoked to explain a high rate of mass transfer requires 16¡ \ i \ 25¡. However, at such small inclination it is difficult to explain the large amplitude of the orbital light curve (D0.5 mag). Alternatively, the results could signify substantial vertical structure in the accretions disks of supersoft X-ray sources. By contrast, a simple model Ðt to the jet outÑow lines indicates an orbital inclination angle of 35¡ \ i \ 60¡.

Simultaneous Photometry and Spectroscopy of the Supersoft X-Ray Source RX J0019.8+2156 (QR Andromedae)

“…This is particularly evident in the work of Deufel et al (1999), who show data for many minima. However, in their study of the jets in QR And, Becker et al (1998) found that the He II emission lines from the jets showed exactly the same phasing and amplitude as the central line (the one we have measured). They concluded that since the jets must be centered on the compact star, the central He II therefore outlines its orbital motion.…”

“…The strongest emission line is He II j4686, a typically dominant line in SSS and X-ray binary spectra. Note that during these low-dispersion observations the satellite "" jet ÏÏ lines (e.g., Becker et al 1998 ;Tomov et al 1998 ;Cowley et al 1998) were not present.…”

“…Based on the radial velocity variations of the system, they inferred a secondary star mass of less than 0.5 assuming the compact star is a white M _ , dwarf. Several groups have found evidence of high-velocity "" jets ÏÏ (about^800 km s~1 ; e.g., Becker et al 1998 ;Tomov et al 1998 ;Cowley et al 1998) visible particularly at He II (j4686), Ha, and Hb. The strengths of these jet lines are variable on a timescale of months, and they are not always present.…”

High-Velocity Jets in Recurrent Nova Outbursts

“…In some of these objects as well as U Sco, nonspherical or jetlike mass ejections are suggested (Taylor et al 1989;Shore 2002). High-velocity bipolar outflows are reported in the supersoft X-ray source RS J0513Ϫ6951 (Crampton et al 1996;Southwell, Livio, & Pringle 1997;Hutchings et al 2002), and low-velocity bipolar jets are observed in a supersoft X-ray source (Becker et al 1998).…”

Cataclysmic variables: New frontiers in multi-wavelength research

“…Winds, on the other hand, are not so well collimated, and exhibit velocities ranging from approximately 10% to 100% of the WD escape velocity, v esc [14]. Evidence for the presence of outflows in the form of Doppler shifted emission features and P Cyg absorption features has been found in the optical spectra of 4 supersoft X-ray binaries [15,16,17,18,19]. The main Balmer lines of the galactic sources RX J0019.8+2156 and MR Vel , as well as the Large Magellanic Cloud (LMC) source RX J0513.9-6951, exhibit P Cyg absorption profiles, together with sharp Doppler-shifted emission features, which are ascribed to emission from collimated jets.…”