Related papers: The low mass ratio contact binary system V728 Herc…
Recent studies of massive binaries with putative black hole companions have uncovered a phase of binary evolution that has not been observed before, featuring a bloated stripped star that very recently ceased transferring mass to a…
Hubble Space Telescope observations of Uranus- and Neptune-crossing object (65489) Ceto/Phorcys (provisionally designated 2003 FX128) reveal it to be a close binary system. The mutual orbit has a period of 9.554 +/- 0.011 days and a…
We present the results of an optical and X-ray monitoring campaign on the short-period massive SB2 binary HD 152218. Combining our HiRes spectroscopic data with previous observations, we unveil the contradictions between the published…
Aims: Study the high-mass X-ray binary X-7 in M33 using broad-band optical data. Methods: We used recently published CFHT r' and i' data for variable stars in M33 to extract the light curve of the optical counterpart of X-7. We combined…
The study of very short-period contact binaries provides an important laboratory in which the most important and problematic astrophysical processes of stellar evolution take place. Short-period contact systems, such as CC Com are…
Luminous Blue Variables (LBVs) are massive stars caught in a post-main sequence phase, during which they are losing a significant amount of mass. As, on one hand, it is thought that the majority of massive stars are close binaries that will…
We present the high precession photometric studies in V band and spectroscopic studies centered around H-alpha line for two extreme mass-ratio short period contact binaries ASAS J082243+1927.0 (V1) and ASAS J085710+1856.8 (V2). The…
Three Algol-type binary systems (IO Cep, IM Cep and TX Ari) showing cyclic orbital period changes are studied. The combination of time of minimum data from the ground-based observations together with high precision photometric data from the…
This work studies the significance of the lightcurve intrinsic variability in the numerical modeling of contact binaries. Using synthetic light curves we are showing that the starspot-based intrinsic variability increases the apparent mass…
Photometric analysis of $BVR_C$ light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11) days. Photometric parameters are determined, as well. The analysis yielded to…
We report the detection of eclipses in LSPM J1112+7626, which we find to be a moderately bright (I_C = 12.14 +/- 0.05) very low-mass binary system with an orbital period of 41.03236 +/- 0.00002 days, and component masses M_1 = 0.395 +/-…
V444 Cyg is a WN5+O6 V eclipsing binary system that exhibits a secular variation in its orbital period due to the loss of matter from the Wolf-Rayet star through its powerful stellar wind. This makes it possible to obtain a dynamical…
\alpha^1 Her is the second closest Asymptotic Giant Branch (AGB) star to the Sun, and the variable luminous M5 Ib-II member of a triple stellar system containing G8 III and A9 IV-V components. However, the mass of this important star was…
Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the eighth set of ten close binary systems: AB And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP Peg, V335…
We revisit various sets of published results from X-ray and optical studies of the Galactic black hole (BH) candidate MAXI J0637-430, which went into outburst in 2019. Combining the previously reported values of peak outburst luminosity,…
Radial velocity measurements and simple sine-curve fits to the orbital velocity variations are presented for the third set of ten contact binary systems: CN And, HV Aqr, AO Cam, YY CrB, FU Dra, RZ Dra, UX Eri, RT LMi, V753 Mon, OU Ser. All…
V746 Cas is known to be a triple system composed of a close binary with an alternatively reported period of either 25.4d or 27.8d and a third component in a 62000d orbit. The object was also reported to exhibit multiperiodic light…
We report the detection of large-amplitude, rapid radial velocity (RV) variations and line-splitting in high-resolution Keck/NIRSPEC spectra of the M9 dwarf LP 413-53. We attribute these features to binary motion. Analyzing data spanning 15…
We performed the first light curve analysis of GW Leo and a new ephemeris is obtained for QT Boo. In the present photometric study of two contact binary systems, we found that the period of these binary systems is decreasing at a rate of…
We report the discovery of a new catacysmic variable system, RXJ051541+0104.6. The optical spectrum has a blue continuum with superposed H~I and He~I and II emission lines. The soft X-ray spectrum is well fit with a 50~eV black body. The…