X-rays and TESS observations of symbiotic binary stars
Nuñez, N. E.; Mukai, K.; Sokoloski, J. L.; Luna, G. J. M.; Oliveira, A. S.; Lima, I. J.; Walter, F. M.; Palivanas, N.
Abstract
Symbiotic stars are strongly interacting binaries composed of a white dwarf accreting from its red giant companion. We studied five symbiotics stars: BD~Cam, V1261~Ori, NQ~Gem, CD~-27~8661, CD~-36~8436 using observations from the Swift/XRT and XMM-Newton satellites in X-rays and from TESS in the optical. The X-ray spectra were fit with absorbed optically thin thermal plasma models, with either single- or multi- temperature. The spectra are all compatible with that arising from the most internal region of the accretion disk; the boundary layer. The TESS observations of these five systems show the presence of flickering, would be related with the existence of an accretion disk. These five symbiotics thus belong to the accretion-powered type, a finding supported by their low X-ray luminosity as well as flickered light curves.