XMM-Newtonand TESS observations of the highly variable polar V496 UMa
Makaleler > Tam Makale · 2022
Yazarlar: Samet Ok, Axel Schwope
Astronomy & Astrophysics, Uluslararası, Wos, 2022, cilt 662, ss A116-A116
DOI: 10.1051/0004-6361/202142813
Özet
Aims.We studied the temporal and spectral behavior of V496 UMa from the optical to the X-ray regimes. Methods.We used archivalXMM-Newtonand TESS observations obtained in 2017 and 2019, respectively, to perform a spectral and timing analysis of the highly variable magnetic CV. Results.The light curves of the TESS andXMM-Newtonsatellites reveal a double-humped pattern modulated with the periodicity of 91.058467 ± 0.00001 min. V496 UMa displays a two-pole accretion geometry in the high accretion state. X-ray spectra from these regions are composed of thermal plasma radiation and soft blackbody components with almost identical temperatures and a total accretion rate ofṀ = 1.4(8) × 10−11 M⊙yr−1. The X-ray centers of the humps show longitudinal shifts of −18° and 4°, and shifts around photometric phase zero of −172° and −186°, for the main hump and second hump, respectively. The long-term ZTF light curves reveal high and low accretions states. Low-state ZTF and SDSS photometric data are consistent with an 0.8 M⊙white dwarf at 10 000 K and a main-sequence donor star with a spectral type of M5.0 at aGaiadetermined distance of 758 pc. Conclusions.V496 UMa is a very bright polar in X-rays when it is in the high state. Due to its unusual geometric structure, mass accretion onto the second accretion pole is interrupted occasionally. This discontinuous behavior does not follow a certain pattern in time and has been observed so far only in the high state. The X-ray light curves display clear evidence of an accretion stream at the photometric phase ofϕ = 0.81, which does not show up in optical light curves. An accurate period was derived using the combined TESS andXMM-Newtondata, which differs by 3.8σfrom published results.