Related papers: The active W UMa type binary star V781 Tau revisit…

We present the first extensive photometric results of CL Aur from our BVRI CCD photometry made on 22 nights from 2003 November through 2005 February. Fifteen new timings of minimum light were obtained. During the past 104 years, the orbital…

The photometric analysis and spectroscopic study of the long period low mass ratio deep contact binary KN Per were executed. The light curves of BV(RI)$_c$-band were from the Ningbo Bureau of Education and Xinjiang Observatory Telescope…

Prompted by X-ray detections from multiple surveys, we investigated the A-type star HD 63021 and found that it is a double-lined spectroscopic binary with highly variable emission associated with the primary star. Analysis of our…

For several hours on 2008 April 19 the T Tauri spectroscopic binary DQ Tau was observed to brighten, reaching a maximum detected flux of 468 mJy and likely making it (briefly) the brightest object at 3 mm in the Taurus star-forming region.…

As part of an All-Sky Automated Survey for SuperNovae (ASAS-SN) search for sources with large flux decrements, we discovered a transient where the quiescent, stellar source, ASASSN-V J192114.84+624950.8, rapidly decreased in flux by…

We report here the tentative discovery of a Jovian planet in orbit around the rapidly pulsating subdwarf B-type (sdB-type) eclipsing binary NY Vir. By using new determined eclipse times together with those collected from the literature, we…

We present an analysis of long-term optical monitoring observations and optical spectroscopic observations of the counterpart to CXOU J205847.5+414637 (high mass X-ray binary system). We search for a variability in the light curve of Be…

The secondary of the famous young binary RW Aur is much less studied than the primary. To compensate this shortcoming, we present here the results of UBVRIJHK photometric, VRI polarimetric and optical spectral observations of RW Aur B. The…

In this work, we present a detailed investigation of five contact binary systems of the W Ursae Majoris (W UMa) type. Multiband photometric observations were conducted using ground-based telescopes in both the northern and southern…

Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the ninth set of ten close binary systems: V395 And, HS Aqr, V449 Aur, FP Boo, SW Lac, KS Peg, IW Per, V592 Per, TU UMi, FO Vir. The first…

The minimum mass ratio for tidal stability of a contact binary containing two unevolved main-sequence stars is calculated to be $\qmin\simeq0.09$ in the case of a mostly radiative primary, and is higher if an appreciable fraction of the…

FU Tau A is a young very low mass object in the Taurus star forming region which was previously found to have strong X-ray emission and to be anomalously bright for its spectral type. In this study we discuss these characteristics using new…

We have detected a strong periodicity of 1.80+/-0.05 hours in photometric observations of the brown dwarf Kelu-1. The peak-to-peak amplitude of the variation is ~1.1% (11.9+/-0.8 mmag) in a 41nm wide filter centred on 857nm and including…

From the radial velocities of the N IV 4058 and He II 4686 emission lines, and the N V 4604-20 absorption lines, determined in digital spectra, we report the discovery that the X-ray bright emission line star Wack 2134 (= WR 21a) is a…

Studies of planetary systems of stars in star-forming regions and young clusters open a window on the formative stages of planetary evolution. We obtained high-cadence high-resolution infrared spectroscopy of the solar-mass Taurus…

Observations of the light curve for the 3.7-day Cepheid RT Aur both before and since 1980 indicate that the variable is undergoing an overall period increase, amounting to +0.082 +-0.012 s/yr, rather than a period decrease, as implied by…

Analyses of very accurate CoRoT space photometry, past Johnson V photoelectric photometry and high-resolution \'echelle spectra led to the determination of improved and consistent fundamental stellar properties of both components of AU Mon.…

Tightest known quadruple systems VW LMi consists of contact eclipsing binary with P_12 = 0.477551 days and detached binary with P_34 = 7.93063 days revolving in rather tight, 355.0-days orbit. This paper presents new photometric and…

We performed new photometric observations for two contact binaries (i.e., CRTS J025408.1+265957 and CRTS J012111.1+272933), which were observed by the 1.0-m telescope at Xingjiang Astronomical Observatory. From our light curves and several…

Variability of the spin period of the white dwarf in the V405 Aur (RX J0558.0+5353) system using our observations and previously published maxima timings is analyzed. As the phase light curve contains two nearly equal photometric waves, one…