Transient emission of selected CRTS Cataclysmic Variables

Abstract

We present optical photometric and spectroscopic observations of three SU UMa-type dwarf novae, i.e. AR Pic, QW Ser and V521 Peg, conducted in 2016 and 2017. These sources were selected from the Catalina Real-Time Transient Survey and observed during quiescence, outburst (AR Pic and QW Ser) and superoutburst (V521 Peg). For AR Pic, strong flickering in the light curves and an asymmetric double-peaked Hβ emission line in the spectra, confirmed the presence of a very active hot spot. During outburst, detected on 18 February 2017, it exhibited a ∼ 3.3 magnitude brightening. The projected velocity of the inner edge of the accretion disc is ∼ 2000 km s −1. An outburst of QW Ser was detected on 8 August 2016. Absorption lines, characteristic of an optically thick disc during outburst, were detected and an outflow velocity of ∼ 1000 km s −1 was determined. Optical spectra during the superoutburst of V521 Peg were obtained for the first time, confirming the superoutburst nature of the outburst, as also observed in other SU UMa-type dwarf novae. The superoutburst was detected on 1 September 2017. Welldefined superhumps were observed, with an average superhump period of P sh ∼ 1.48 hr. A mass ratio of q ∼ 0.14 was determined from the period excess of ε ∼ 3%.

Investigation of WZ Sge-type Dwarf Nova ASASSN-19oc: Optical Spectroscopy and Multicolor Light Curve Analysis

“…Such a spectrum, in which high-order Balmer absorption dominates during an initial outburst stage, is typical for DNe (Hessman et al 1984). In particular, it was also observed in other SU UMa-type stars, for example, in V521 Peg, QW Ser (Szegedi et al 2017), V344 Lyr, RZ LMi (Han et al 2020), and PNV J00215475+5231007 (Taguchi 2023). The spectra of 11 DNe during outbursts (AR And, X Leo, CZ Ori, etc.)…”