Related papers: The active W UMa type binary star V781 Tau revisit…
We present the first UBV and uvby photometric observations for the short period variable star HV Ursae Majoris classified as a field RRc variable. The observed differences between the consecutive minima and the lack of colour variations…
Cygnus X-1 is a binary star system that is comprised of a black hole and a massive giant companion star in a tight orbit. Building on our accurate distance measurement reported in the preceding paper, we first determine the radius of the…
For more than half a century, the puzzling W-type phenomenon in contact binaries has challenged astrophysicists. In these systems, the less massive component exhibits a higher surface temperature than its more massive companion, which is a…
We aim at searching for secular evolution of the orbital period in the short-period binary system WR 127 (WN3b+O9.5V, $P = 9.555^d$). We performed new low-resolution spectroscopic observations of WR 127 on 2.5-m CMO SAI telescope to…
The ~2 Myr old classical T Tauri star CI Tau shows periodic variability in its radial velocity (RV) variations measured at infrared (IR) and optical wavelengths. We find that these observations are consistent with a massive planet in a…
We characterize ${\sim} 71,200$ W UMa type (EW) contact binaries, including ${\sim} 12,600$ new discoveries, using ASAS-SN $V$-band all-sky light curves along with archival data from Gaia, 2MASS, AllWISE, LAMOST, GALAH, RAVE, and APOGEE.…
71 Tau was discovered to be a $\delta$ Scuti star by Horan (1979, AJ 84, 1770). To our knowledge no other photometry of this star has been published. 71 Tau is the second brightest X-ray source in the Hyades and has been shown to be…
Context. Both the stellar activity and the accretion processes of young stellar objects can induce variations in their radial velocity (RV). This variation is often modulated on the stellar rotation period and may hide a RV signal from a…
ASAS J174406+2446.8 was originally found as a $\delta$ Scuti-type pulsating star with the period P=0.189068 $days$ by ASAS survey. However, the LAMOST stellar parameters reveal that it is far beyond the red edge of pulsational instability…
We present new multiband CCD photometry for AA UMa made on 8 nights between January and March 2009; the $R$ light curves are the first ever compiled. Historical light curves, as well as ours, display partial eclipses and inverse O'Connell…
We present photometric and spectroscopic data analysis and orbital period study of an early-type interacting binary system V382 Cyg by using all the available data. We made a simultaneous light and radial velocity curve solution. The…
We present new long-term CCD photometry for EP And acquired during the period 2007 to 2012. The light curves display total eclipses at primary minima and season-to-season light variability. Our synthesis for all available light curves…
We carry out a re-analysis of the photometric data in Cousin RI bands which was taken under the Nainital Microlensing Survey during 1998 to 2002 with the aim to detect gravitational microlensing events in the direction of M31. Here, we do…
We report the results from our analysis of 8 years of the data for the gamma-ray binary LS I +61 303, obtained with the Large Area Telescope onboard the Fermi Gamma-Ray Space Telescope. We find a significant dip around the binary's…
Time-resolved observations of a 6' x 6' field, containing the position error boxes of the X-ray source 1WGA J1958.2+3232, were performed in June 1999 with the 91 cm Catania telescope, equipped with a Photon Counting Intensified CCD. The…
WR 31a (Hen 3-519) is likely a post-luminous blue variable (LBV) star that is evolving to become a classical Wolf-Rayet star. Multicolor (UBVR) photopolarimetric observations of WR 31a were obtained over nine nights in early 2007. The…
We report here the first results from a 15-yr long variability monitoring of the z=2.0 quasar QSO B1312+7837. It shows luminosity changes with a period P~6.13 yr (P~2.04 yr at rest frame) and an amplitude of ~0.2mag, superimposed on a…
Images of the Kuiper belt object (126719) 2002 CC249 obtained in 2016 and 2017 using the 6.5m Magellan-Baade Telescope and the 4.3m Discovery Channel Telescope are presented. A lightcurve with a periodicity of 11.87+/-0.01 h and a…
We report results of a spectropolarimetric monitoring of the young Sun-like star V1298~Tau based on data collected with the near-infrared spectropolarimeter SPIRou at the Canada-France-Hawaii Telescope between late 2019 and early 2023.…
With an orbital period of about 3.078 days, the double-lined spectroscopic binary HD 48099 is, still now, the only short-period O+O system known in the Mon OB2 association. Even though an orbital solution has already been derived for this…