Related papers: Quest for the Donor Star in the Magnetic Precatacl…
V1082 Sgr is a cataclysmic variable with accretion luminosity above $10^{34}$erg s$^{-1}$, indicating a mass transfer rate above $10^{-9}M_{\odot}$yr$^{-1}$. However, its K type companion was suggested to be under-filling its Roche lobe…
We studied two objects identified as a Cataclysmic Variables (CVs) with periods exceeding the natural boundary for Roche lobe filling ZAMS secondary stars. We present observational results for V1082 Sgr with 20.82 h orbital period, an…
We present a long-term light curve of the precataclysmic variable (CV) V1082 Sgr obtained by the K2-mission over the course of 81 days. We analyze the entire complex light curve as well as explore several sections in detail with a sliding…
We conducted a multi-wavelength study to unveil the properties of the extremely long-period cataclysmic variable V479 And. We performed series of observations, including moderate to high spectral resolution optical spectrophotometry, X-ray…
The overwhelming majority of CVs have orbital periods shorter than 10 hr. However, a few have much longer periods, and their formation and existence pose challenges for the CV evolution models. These extremely long-period CVs must host…
Context. We present time-resolved spectroscopy and photometry of HS 0218+3229, a new long-period cataclysmic variable discovered within the Hamburg Quasar Survey. It is one of the few systems that allow a dynamical measurement of the masses…
Context: A detailed study of the close interacting binary V4142\,Sgr based on photometric and spectroscopic analysis is presented.This system belongs to the enigmatic class of Algol-like variables showing a long photometric cycle of unknown…
Intermediate resolution (0.5-1 Angs) optical spectroscopy of the cataclysmic variable SY Cnc reveals the spectrum of the donor star. Our data enable us to resolve the orbital motion of the donor and provide a new orbital solution, binary…
We present phase-resolved spectroscopy and photometry of the optical counterpart to the X-ray binary IGR J19308+0530. Ellipsoidal modulations in the light curve show that the F-type companion star in the system is Roche lobe filling. The…
We present time-resolved optical and ultraviolet spectroscopy and photometry of V1460~Her, an eclipsing cataclysmic variable with a 4.99\,h orbital period and an overluminous K5-type donor star. The optical spectra show emission lines from…
We report the discovery of 1RXH J082623.6-505741, a 10.4 hr orbital period compact binary. Modeling extensive optical photometry and spectroscopy reveals a $\sim 0.4 M_{\odot}$ K-type secondary transferring mass through a low-state…
The orbital period of V Sge is decreasing at a rate which increased from dP/dt=-(4.11\pm 0.33)\times 10^{-10} in 1962 to -(5.44\pm 0.61)\times 10^{-10} in 2022. This implies that the mass trahsfer from the secondary component is…
Recently the first finding of a spin period of an accreting neutron star in M31 is reported. The observed spin period is 1.2 s and it shows 1.27 d modulations due to orbital motion. From the orbital information, the mass donor could not be…
The donor in the microquasar GRS 1915+105 is a low-mass giant. Such a star consists of a degenerate helium core and a hydrogen-rich envelope. Both components are separated by a hydrogen burning shell. The structure of such an object is…
We present a dynamical study of the intermediate polar cataclysmic variable YY Dra based on time-series observations in the $K$ band, where the donor star is known to be the major flux contributor. We covered the $3.97$-h orbital cycle with…
We report the discovery of ZTF J0127+5258, a compact mass-transferring binary with an orbital period of 13.7 minutes. The system contains a white dwarf accretor, which likely originated as a post-common envelope carbon-oxygen (CO) white…
The binary parameters of the microquasar GRS 1915+105 have been determined by the detection of Doppler-shifted 12CO and 13CO lines in its K-band spectrum (Greiner et al., 2001, Nature, 414, 522). Here, we present further analysis of the…
We constrain the binary parameters of the eclipsing accreting X-ray binary IGR J17451--3022 and the nature of its donor star. The donor mass, its radius, and the system inclination angle are computed based on the system orbital period and…
Among the 28,000 targeted stars in K2 Field 10 is the white dwarf WD 1202-024 (EPIC 201283111), first noted in the SDSS survey (SDSS 120515.80-024222.7). We have found that this hot white dwarf (Teff = 22,640 K) is in a very close orbit (P…
We present the first detection of the mass donor star in the cataclysmic variable WZ Sge. Phase resolved spectroscopy reveals narrow Balmer emission components from the irradiated secondary star during the 2001 outburst. Its radial velocity…