Observations of V592 Cas - An Outflow at Optical Wavelengths

TL;DR

This study presents optical spectra of V592 Cas revealing episodic, phase-dependent outflows with high velocities, suggesting asymmetry and potential origins in disk hotspots, with no direct link to optical brightness variations.

Contribution

First detailed optical spectral analysis of V592 Cas's outflow, highlighting its episodic, asymmetric nature and potential origin in disk hotspots.

Findings

Outflows reach velocities of 5000 km/sec.

Wind signatures are phase-dependent and episodic.

No clear correlation between optical brightness and outflow strength.

Abstract

We present new red optical spectra of V592 Cas aimed at exploring the properties of the outflow of this system in a spectral region where the underlying white dwarf and the accretion disk do not contribute significantly to the observed absorption components of the H-alpha and HeI line profiles. We use the H-alpha emission line to study the wind, which appears as pronounced blueshifted P-Cygni absorption troughs whose low velocity end contaminates the blue side of the emission line profile. The wind appears to be episodic in nature, with multiple events reaching velocities of 5000km/sec in H-alpha. Similar (but weaker) wind signatures appear in the HeI5876AA line but are absent in HeI6678AA. Our data suggest that during wind episodes the wind is phase dependent and is visible for half the orbit of the system. Considering that V592 Cas is viewed almost face-on, the symmetry axis of the outflow can not be orthogonal to the disk and/or the outflow must have some other inherent asymmetry in outflow geometry. A possible origin of the wind is in a disk hotspot, either at the initial impact point of the accretion stream on the disk edge or as a result of disk overflow (similar to SW Sextantis stars). Simultaneous optical photometry during one night of our spectroscopic observations indicate that there is no clear relationship between the optical brightness variations and the strength of the outflow in this system.