Related papers: The ambiguous transient ASASSN-17hx. A possible no…

We detected the second historical outburst of the 1920 nova IM Nor. Accurate astrometry of the outbursting object revealed the true quiescent counterpart having a magnitude of R=17.0 mag and B=18.0 mag. We show that the quiescent…

The discovery of novae as sources of ~GeV gamma-rays highlights the key role of shocks and relativistic particle acceleration in these transient systems. Although there is evidence for a spectral cut-off above energies ~1-100 GeV at…

We present outburst and quiescence spectra of the classical nova KT Eri and discuss the appearance of a sharp HeII 4686 Ang emission line, whose origin is a matter of discussion for those novae that showed a similar component. We suggest…

Novae are now firmly established as a high-energy (>100 MeV) gamma-ray source class by the Fermi Large Area Telescope (LAT). In symbiotic binary systems such as V407 Cyg 2010, there is a firm theoretical framework for the production of…

We have monitored the return to quiescence of novae previously observed in outburst as supersoft X-ray sources, with optical photometry of the intermediate polar (IP) V4743 Sgr and candidate IP V2491 Cyg, and optical spectroscopy of these…

The total masses ejected during classical nova eruptions are needed to answer two questions with broad astrophysical implications: Can accreting white dwarfs be pushed towards the Chandrasekhar mass limit to yield type Ia supernovae? Are…

Recent interpretations of narrow, variable absorption lines detected in some Type Ia supernovae suggest that their progenitors are surrounded by dense, circumstellar material. Similar variations detected in the symbiotic recurrent nova…

On 2018, April 29, a bright classical nova (CN) Per 2018 was discovered. Its progenitor is a well-known dwarf nova V392 Per. In this contribution, we analyze $UBVR_{C}I_{C}$ photometry and optical spectroscopy of the CN V392 Per. From the…

The study of novae is continued and a self-consistent updated physical model for classical/recurrent novae derived from multi-wavelength observations is presented. In particular, observations of novae support the origin of the optical…

We report on the discovery of AT2018lqh (ZTF18abfzgpl) -- a rapidly-evolving extra-galactic transient in a star-forming host at 242 Mpc. The transient g-band light curve's duration above half-maximum light is about 2.1 days, where 0.4/1.7…

We investigate the expected rates and bolometric light-curve properties of stripped-envelope electron-capture supernovae (ECSNe) using stellar models from the Binary Population and Spectral Synthesis (BPASS) code. We find that 0.8 per cent…

Swift J174610.4-290018 is a peculiar transient X-ray source in the Galactic center. First detected by Swift at the onset of an outburst in February 2024, it has since been observed intentionally and serendipitously by multiple X-ray…

We study the long-term evolution of ejecta formed in a binary neutron star (BNS) merger that results in a long-lived remnant NS by performing a hydrodynamics simulation with the outflow data of a numerical relativity simulation as the…

We present optical photometric and spectroscopic observations of the 02es-like type Ia supernova (SN) 2022ywc. The transient occurred in the outskirts of an elliptical host galaxy and showed a striking double-peaked light curve with an…

Peaking at 3.7 mag on 2020 July 11, YZ Ret was the second-brightest nova of the decade. The nova's moderate proximity (2.7 kpc from Gaia) provided an opportunity to explore its multi-wavelength properties in great detail. Here we report on…

Supergiant fast X-ray transients are a new class of high mass X-ray binaries recently discovered with INTEGRAL. Hours long outbursts from these sources have been observed on numerous occasions at luminosities of ~1E36-1E37 erg/s, whereas…

We present the photometric and spectroscopic evolution of the Type II supernova (SN II) SN 2017ivv (also known as ASASSN-17qp). Located in an extremely faint galaxy (M$_r=-10.3$ mag), SN 2017ivv shows an unprecedented evolution during the…

Type Ia supernovae are thought to be the outcome of the thermonuclear explosion of a carbon/oxygen white dwarf in a close binary system. Their optical light curve is powered by thermalized gamma-rays produced by the radioactive decay of…

We present a spectral analysis of XMM-Newton data of ten dwarf novae, nine of which were observed during a quiescent state. The X-ray spectra indicate the presence of a hot, optically thin plasma with a temperature distribution consistent…

We report on the discovery and observations of the extremely luminous optical transient CSS100217:102913+404220 (CSS100217 hereafter). Spectroscopic observations show this transient was coincident with a galaxy at redshift z=0.147, and…