Liverpool Telescope and Swift Observations of V392 Persei
ATel #12951; F. J. Murphy-Glaysher (LJMU), M. J. Darnley (LJMU), K. L. Page (Leicester)
on 22 Jul 2019; 19:47 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)
Subjects: Optical, Ultra-Violet, X-ray, Cataclysmic Variable, Nova
Referred to by ATel #: 13381
The previously identified dwarf nova V392 Persei experienced its first reported (thermonuclear) nova eruption on or around 2018 April 29 (see CBAT). The eruption and subsequent decline have been followed extensively from the ground and from low-Earth orbit (see ATel #11588, #11590, #11594, #11601, #11605, #11617, #11647, #11846, #11872, #11905 and #11926, ARAS, and Darnley & Starrfield 2018 for further details).
On around 2019 July 18, V392 Per exited Sun constraint for the second time post-eruption. Liverpool Telescope photometric and spectroscopic observations, along with X-ray spectroscopy and near-ultraviolet photometry from the Neil Gehrels Swift Observatory, were obtained at the earliest opportunity.
Prior to entering the second Sun constraint, on around 2019 April 26, the optical and UV decline (following the 2018 eruption) had slowed substantially, but the system had not returned to pre-eruption levels. The optical spectra were dominated by broad forbidden lines of [O III] at 4959 and 5007 Å, all on top of a red (due to high extinction) continuum. The X-ray spectra had remained broadly consistent over the last observing period and could be fitted acceptably with a single hot APEC model.
These post-Sun constraint observations show that the behaviour of the system has not altered during the three months of inaccessibility, particularly the optical and NUV light curves and the X-ray spectroscopy. However, the Liverpool Telescope spectra indicate that the nebular phase of the eruption may have begun to wane.
Liverpool Telescope and Swift observations of the system are planned to continue, albeit at lower cadence, as the system slowly returns to its quiescent state. As a known dwarf nova, it will be interesting to see how long it will take for disk instability outbursts to resume.
