Related papers: Determination of the basic parameters of the dwarf…

We present the first orbital elements for the massive close binary, HD 115071, a double-lined spectroscopic binary in a circular orbit with a period of 2.73135 +/- 0.00003 days. The orbital semiamplitudes indicate a mass ratio of M_2/M_1 =…

V2491 Cygni (Nova Cygni 2008 No.2) was detected as a transient supersoft X-ray source with the Swift XRT as early as 40 days after the outburst, suggesting a very massive white dwarf (WD) close to the Chandrasekhar limit. We present a…

We present fast timing photometric observations of the intermediate polar V2069 Cygni (RX J2123.7+4217) using the Optical Timing Analyzer (OPTIMA) at the 1.3 m telescope of Skinakas Observatory. The optical (450-950 nm) light curve of V2069…

ASAS photometric observations of LS 1135, an O-type SB1 binary system with an orbital period of 2.7 days, show that the system is also eclipsing. This prompted us to re-examine the spectra used in the previously published spectroscopic…

We present the first detection of photometric variability of a spectroscopically-confirmed Y dwarf. The Infrared Array Camera on board the Spitzer Space Telescope was used to obtain times series photometry at 3.6 and 4.5 microns over a…

The Cyg OB2 #5 system is thought to consist of a short-period (6.6 d) eclipsing massive binary orbited by an OB-star orbiting with a period of ~6.7 yr; these stars in turn are orbited by a distant early B-star with a period of thousands of…

$\theta$ Cygni is an F3 spectral-type main-sequence star with visual magnitude V=4.48. This star was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were…

We present red spectra in the region 7000-8300A of the eclipsing dwarf nova IP Peg, with simultaneous narrow-band photometry centered at 7322A. We show that by placing a second star on the slit we can correct for the telluric absorption…

We present a second paper related to the analyses of high-dispersion spectroscopic observations of the magnetic cataclysmic variable AE Aquarii. We focus our efforts on the study of the emission lines and their radial velocities. We detect…

We present high and intermediate resolution spectroscopy of the X-ray nova Centaurus X-4 during its quiescent phase. Our analysis of the absorption features supports a K3-K5V spectral classification for the companion star, which contributes…

An analysis of accurate radial velocities (RVs) of the Be star gamma Cas from 295 Reticon spectrograms secured between October 1993 and May 2000 allowed us to prewhiten the RVs for the long-term changes and to obtain the first orbital RV…

We use a combination of X-shooter spectroscopy, ULTRACAM high-speed photometry and SOFI near-infrared photometry to measure the masses and radii of both components of the eclipsing post common envelope binaries SDSS J1212-0123 and GK Vir.…

We determine the age of the eclipsing binary V380 Cygni, whose components have a significant mass ratio, $M_B/M_A\approx$ 0.6. Because this binary exhibits spectral lines of both components, the values of masses and radii could be…

The Kepler light curve of DF Cyg is unparalleled in precision and cadence for any RV Tau star to date spanning a baseline of $\sim$4 years and clearly displaying the signature pulsating behavior of alternating deep and shallow minima as…

Chandra data of the X-ray source [PMH2004] 47 were obtained in the ACIS Survey of M 33 (ChASeM33) in 2006. During one of the observations, the source varied from a high state to a low state and back, in two other observations it varied from…

We study properties of the superorbital modulation of the X-ray emission of Cyg X-1. We find that it has had a stable period of about 300 d in soft and hard X-rays and in radio since 2005 until at least 2010, which is about double the…

We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which had been ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a…

In the first paper of this series, we presented a detailed high-resolution spectroscopic study of CPD - 41degr7742, deriving for the first time an orbital solution for both components of the system. In this second paper, we focus on the…

Q Cygni (Nova Cygni 1876) is the third oldest old novae (after WY Sge and V841 Oph) with a long orbital period of 10.08 hours and spectroscopic peculiarities in the optical including the presence of variable wind outflow revealed by optical…

(Abridged) We present spectroscopic and photometric observations of the eclipsing system V1061 Cyg (P = 2.35 days). We show that it is a hierarchical triple in which the third star is visible in the spectra. We combine the radial velocities…