Related papers: Optical spectroscopy of the dwarf nova U Geminorum

We have discovered a dwarf nova (DN) of type SU UMa in Kepler data which is 7.0 arcsec from the G-type exoplanet survey target KIC 4378554. The DN appears as a background source in the pixel aperture of the foreground G star. We extracted…

About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. OVIII) in their optical spectra when entering the white dwarf cooling sequence. The recent discovery of a both spectroscopic and photometric variable…

We present the discovery of a peculiar dwarf nova KSP-OT-201712a using high-cadence, multi-color observations made with the Korea Microlensing Telescope Network. KSP-OT-201712a exhibits a rare presence of outbursts during standstills as…

A CCD photometry of the dwarf nova MASTER OT J172758.09 +380021.5 was carried out in 2019 during 134 nights. Observations covered three superoutbursts, five normal outbursts and quiescence between them. The available ASASSN and ZTF data for…

We report the analysis of time-series of infrared $JHK_s$ photometry of the dwarf nova V2051 Oph in quiescence with eclipse mapping techniques to investigate structures and the spectrum of its accretion disc. The light curves after removal…

Deep optical CCD images of the supernova remnant G 32.8-0.1 were obtained where filamentary and diffuse emission was discovered. The images were acquired in the emission lines of Halpha+[N II] and [S II]. Filamentary and diffuse structures…

We present an analysis of the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) far ultraviolet snapshot spectrum of the dwarf nova BZ UMa taken during quiescence. We find that the flux continuum is consistent with that…

The disc instability model accounts well for most of the observed properties of dwarf novae and soft X-ray transients, but the rebrightenings, reflares, and echoes occurring at the end of outbursts or shortly after in WZ Sge stars or soft…

We present time-resolved optical spectroscopy of the dwarf nova CSS100603:112253-111037. Its optical spectrum is rich in helium, with broad, double-peaked emission lines produced in an accretion disc. We measure a line flux ratio…

We performed deep optical observations of the area of the new supernova remnant G 69.4+1.2 in the emission lines of [O III], Halpha+[N II] and [S II]. The low ionization images reveal diffuse and filamentary emission in the central and…

We present time-resolved spectroscopy and photometry of CSS 120422:111127+571239 (= SBS1108+574), a recently discovered SU UMa-type dwarf nova whose 55-minute orbital period is well below the CV period minimum of ~78 minutes. In contrast…

Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed…

We present the ultraviolet spectrum of the SW Sex star and nova-like variable DW UMa in an optical low state, as observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope (HST). The data are well described…

We present here new observations of the eccentric debris ring surrounding the Gyr-old solar-type star HD 202628: at millimeter wavelengths with ALMA, at far-infrared wavelengths with \textit{Herschel}, and in scattered light with…

We present constraints on the deuterium to hydrogen ratio (D/H) in the metal-poor gas cloud at redshift $z=0.701$ towards QSO 1718+4807. We use new Keck spectra in addition to Hubble Space Telescope (HST) and International Ultraviolet…

We investigated the nature of the hitherto unresolved elliptical infrared emission in the centre of the ~20000 AU disc silhouette in M 17. We combined high-resolution JHKsL'M' band imaging carried out with NAOS/CONICA at the VLT with [Fe…

The 3D Radioastronomical Approach to Doppler tomography has been used to study the H$\alpha$ emission sources in U Coronae Borealis. These 3D tomograms provide greater resolution than the projected 2D version and highlight the jet-like gas…

We present the first reliable determination of the orbital period of the recurrent nova V2487 Oph (Nova Oph 1998). We derived a value of $0.753 \pm 0.016$ d ($18.1 \pm 0.4$ h) from the radial velocity curve of the intense He II…

We report on a 39 ks observation of the 7.7-s low-mass X-ray binary pulsar 4U1626-67 with the High Energy Transmission Grating Spectrometer (HETGS) on the Chandra X-Ray Observatory. This ultracompact system consists of a disk-accreting…

We present a detailed study of the MASTER OT J030227.28+191754.5 outburst in 2021-2022, reaching an amplitude of 10.2 mag and a duration of 60 d. The detections of (1) the double-peaked optical emission lines, and (2) the early and ordinary…