EXPLORANDO VARIÁVEIS CATACLÍSMICAS COM SIMILARIDADES OBSERVACIONAIS DE ANÃS BRANCAS ACRETANTES MAGNÉTICAS E NÃO-MAGNÉTICAS

Abstract

Cataclysmic Variables (CVs) are binary systems in which a white dwarf (WD) accretes matter from a companion star on or near the main sequence. Some of the uncertainties about these systems revolve around the following points: population studies and determination of parameter space at the threshold between systems harboring accreting magnetic and non-magnetic white dwarfs. These points were addressed in this work through a multispectral analysis. In the first approach, we used a sample of systems classified as dwarf novae (DNs), yet with optical spectral characteristics similar to those of low-luminosity intermediate polar-like X-ray sources (LLIPs), LLIPs, and polars. In the second approach, we focused on characterizing CVs identified in S-PLUS. The work utilized (i) a collection of observations, with optical spectroscopy performed using GMOS/Gemini-South and X-ray observations with the Swift satellite, along with optical and ultraviolet photometry from the same satellite, (ii) observations and information from public databases such as light curves from the TESS satellite and the ASAS-SN project, optical spectroscopy from LAMOST and SDSS, magnitude and distance measurements from the GAIA satellite, and flux measurements from the eROSITA satellite, and (iii) information available in the literature. In terms of population, we characterized and confirmed 11 new CVs based on characteristic lines from Balmer Series of H, HeI, and HeII at 4686 Å. Additional confirmation of this nature for four systems came through X-ray observations performed with the Swift telescope. The observed X-ray luminosities were consistent with those expected for LLIPs and DNs. One system stands out, in which we determined an orbital period of 1.81 hours, revealed in TESS light curves, whose orbital and spectral characteristics are consistent with those of IPs and certain NAs. However, the non-detection of the white dwarf spin period from TESS observations suggests it is an DN. Furthermore, two of these eleven systems were identified, based on spectral similarities (notably in HeII 4686 emissions, Hα, and Hβ), as polars. Regarding the parameter space between CVs, polars tend to have lower equivalent widths for Hα and Hβ lines, with a relationship suggesting higher EW(Hα) values are associated with higher Hβ values. In polars, the ratio EW(Hα)/EW(Hβ) as a function of EW(HeII 4686) indicates that intense emissions of HeII at 4686 Å are preferentially associated with optically thick astrophysical environments to Hα photons. Additionally, polars exhibit greater variation in EW(HeII 4686)/EW(Hα), always exceeding 0.2, but without correlation with EW(Hα) values. On the other hand, DNs and LLIPs show greater dispersion in EW(Hα) and EW(Hβ) values, extending up to approximately 200 Å. HeII emission at 4686 Å in DNs and LLIPs is always associated with EW(HeII 4686) values below 15 Å indicating relatively weak emissions compared to polars. There is no distinction among HeII 4686, Hα, and Hβ emissions between DNs and LLIPs studied, making differentiation based solely on these lines impossible. The ratio EW(HeII 4686)/EW(Hα) for DNs and LLIPs is consistently low, below 0.2, reflecting weak HeII emissions at 4686 Å compared to Hα. Furthermore, no significant trends were observed between equivalent widths and orbital periods of the systems in any of the classes.