The SW Sex-type star 2MASS J01074282+4845188: an unusual bright accretion disk with non-steady emission and a hot white dwarf

TL;DR

This study presents detailed observations of the unusual nova-like star 2MASS J01074282+4845188, revealing a bright, non-steady accretion disk, a very hot white dwarf, and characteristics consistent with SW Sex-type cataclysmic variables.

Contribution

The paper provides the first comprehensive light curve modeling and spectral analysis of 2MASS J01074282+4845188, highlighting its unique features and classification as an SW Sex-type nova-like star.

Findings

Deepest permanent eclipse among known nova-like stars.

High temperature of the accretion disk during quiescence.

Evidence of non-steady emission in the accretion disk.

Abstract

We present new photometric and spectral observations of the newly discovered nova-like eclipsing star 2MASS J01074282+4845188. To obtain a light curve solution we used model of a nova-like star whose emission sources are a white dwarf surrounded by an accretion disk, a secondary star filling its Roche lobe, a hot spot and a hot line. 2MASS J01074282+4845188 shows the deepest permanent eclipse among the known nova-like stars. It is reproduced by covering the very bright accretion disk by the secondary component. The luminosity of the disk is much bigger than that of the rest light sources. The determined high temperature of the disk is typical for that observed during the outbursts of CVs. The primary of 2MASS J01074282+4845188 is one of the hottest white dwarfs in CVs. The temperature of 5090 K of its secondary is also quite high and more appropriate for a long-period SW Sex star. It might be explained by the intense heating from the hot white dwarf and the hot accretion disk of the target. The high mass accretion rate $\dot{M} = 8\times 10^{-9} M_{\sun}$ yr$^{-1}$, the broad and single-peaked H$\alpha$ emission profile, and the presence of an S-wave are sure signs for the SW Sex classification of 2MASS J01074282+4845188. The obtained flat temperature distribution along the disk radius as well as the deviation of the energy distribution from the black-body law are evidence of the non-steady emission of the disk. The close values of the disk temperature and the parameter $\alpha_{g}$ of 2MASS J01074282+4845188 and those of the cataclysmic stars at eruptions might be considered as an additional argument for the permanent active state of nova-like stars.