Related papers: Study of the peculiar variable star Khavchenko 1

This work is a continuation of the studies of the ultrafast variability of line profiles in the spectra of early-type stars. Line profile variations (LPVs) in the spectrum a chemically peculiar A0Vp star $\alpha^2\,$CVn are investigated…

Extensive time-resolved observations of Kuiper Belt object 2001 QG298 show a lightcurve with a peak-to-peak variation of 1.14 +-0.04 magnitudes and single-peaked period of 6.8872 +- 0.0002 hr. The mean absolute magnitude is 6.85 magnitudes…

We present ten years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F$-$G spectral types;…

All data available in B band for the BL Lac object MRK421 from 22 publications are used to construct a historical light curve, dating back to 1900. It is found that the light curve is very complicated and consists of a set of outbursts with…

A search of the first Data Release of the VISTA Variables in the Via Lactea (VVV) Survey discovered the exceptionally red transient VVV-WIT-01 ($H-K_s=5.2$). It peaked before March 2010, then faded by $\sim$9.5 mag over the following two…

We present high cadence (1-10 hr^-1) time-series photometry of the eruptive young variable star V1647 Orionis during its 2003-2004 and 2008-2009 outbursts. The 2003 light curve was obtained mid-outburst at the phase of steepest luminosity…

The enigmatic star KIC 8462852, informally known as "Boyajian's Star", has exhibited unexplained variability from both short timescale (days) dimming events, and years-long fading in the Kepler mission. No single physical mechanism has…

Spectra of planetary nebulae (PNe) are characterised by strong forbidden emission lines and often also by an infrared (IR) excess. A few PNe show dust obscuration events and/or harbour long-period binaries. Some post-asymptotic giant branch…

We present the light curve of an unusual variable object, OGLE #7, detected during the OGLE search for microlensing events. After one season of being in a low, normal state, the star brightened by more than 2~mag with a characteristic…

Nova-like variables are high-accretion-rate cataclysmic variables (CVs) that, in contrast to dwarf novae, do not undergo outbursts caused by thermal-viscous instability. However, a small group of nova-likes, classified as AH Pic-type stars,…

We present time-series observations, spectra and archival outburst data of a newly-discovered variable star in Hercules, Var Her 04. Its orbital period, mass ratio, and outburst amplitude resemble those of the UGWZ-type subclass of UGSU…

The X-ray source 1E 1207.4-5209 is a compact central object in the G296.5+10.0 supernova remnant. Its spin period of 424 ms, discovered with the Chandra X-ray Observatory, suggests that it is a neutron star. The X-ray spectrum of this…

(Abridged) We studied the brightness and spectral evolution of the young eruptive star V1647 Ori during its recent outburst in the period 2004 February - 2006 Sep. We performed a photometric follow-up in the bands V, R_C, I_C, J, H, K_s as…

GSC 4560-02157 is a new eclipsing cataclysmic variable with an orbital period of $0.265359$ days. By using the published $V-$ and $R-$band data together with our observations, we discovered that the $O-C$ curve of GSC 4560-02157 may shows a…

We report extensive photometry of the dwarf nova V660 Herculis. During our campaign, lasting from August 2003 to November 2004, we recorded one bright eruption which turned out to be a superoutburst lasting about 15 days and having…

The recurrence of a previously documented eclipse of a solar-like pre--main-sequence star in the young cluster IC 348 has been observed. The recurrence interval is 4.7 $\pm 0.1$ yr and portions of 4 cycles have now been seen. The duration…

We investigate the question whether there is a real difference in the light change between stars classified as semiregular (SRV) or irregular (Lb) variables by analysing photometric light curves of 12 representatives of each class. Using…

We present spectroscopy of seven cataclysmic variable stars with orbital periods P(orb) greater than 5 hours, all but one of which are known to be dwarf novae. Using radial velocity measurements we improve on previous orbital period…

A majority part of magnetic chemically peculiar (mCP) stars of the upper main sequence exhibits strictly periodic light, magnetic, radio, and spectral variations that can be fully explained by the model of a rigidly rotating main-sequence…

Photometric observations and analysis of FY Lac were performed in order to determine the variability characteristics, using measurements taken at Loiano site of Bologna Astronomical Observatory and AAVSO data. The star shows a Long Term…