Related papers: V605 Aquilae: a born again star, a nova or both?
The precise origin of Type Ia supernovae (SNe Ia) is unknown despite their value to numerous areas in astronomy. While it is a long-standing consensus that they arise from an explosion of a carbon/oxygen white dwarf, the exact progenitor…
The genesis and chemical patterns of the metal poor stars in the galactic halo remains an open question. Current models do not seem to give a satisfactory explanation for the observed abundances of Lithium in the galactic metal-poor stars…
The source of the Galactic Lithium (Li) has long been a puzzle. With the discovery of Li in novae, extensive research has been conducted. However, there still exists a significant disparity between the observed abundance of lithium in novae…
The close correlation between cooling flows and emission-line nebulae in clusters of galaxies has been recognized for over a decade and a half, but the physical reason for this connection remains unclear. Here we present deep optical…
We present an analysis of elemental abundances of ejecta of the recurrent nova RS Oph using published optical and near-infrared spectra during the 2006 outburst. We use the CLOUDY photoionization code to generate synthetic spectra by…
Aquila X-1 is a prototypical neutron star low mass X-ray binary and one of the most studied X-ray transients. We present optical spectroscopy obtained with the Gran Telescopio Canarias (10.4 m) during the 2016 outburst, the brightest in…
A nova is a cataclysmic event on the surface of a white dwarf in a binary system that increases the overall brightness by several orders of magnitude. Although binary systems with a white dwarf are expected to be overabundant in globular…
The evolution of central stars of planetary nebulae can proceed in several distinct ways, either leading to H-deficiency or to H-normal surface composition. Several new simulations of the evolution channels that lead to H-deficiency are now…
Nova Cen 2013 (V1369 Cen) is the fourth bright nova observed panchromatically through high resolution UV+optical multi epoch spectroscopy. It is also the nova with the richest set of spectra (both in terms of data quality and number of…
In the favored progenitor scenario, Type Ia supernovae arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star;…
Our photometric and spectroscopic monitoring shows that starting with 2020 June 4, day +217 from optical maximum and well into its advanced nebular stage, Nova Sct 2019 began displaying a series of nine large amplitude flares (up to…
Every supernova hitherto observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin,…
Massive stars end their short lives in spectacular explosions, supernovae, that synthesize new elements and drive galaxy evolution. Throughout history supernovae were discovered chiefly through their delayed optical light, preventing…
The radio light curves of novae rise and fall over the course of months to years, allowing for detailed observations of the evolution of the nova shell. However, the main parameter determined by radio models of nova explosions - the mass of…
During the late stages of their evolution, Sun-like stars bring the products of nuclear burning to the surface. Most of the carbon in the Universe is believed to originate from stars with masses up to a few solar masses. Although there is a…
The planetary nebula (PN) A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using HST images we have detected the angular expansion of these knots and derived an age of…
The evidence for the presence of optically thick winds, produced by classical novae after optical maximum, has been challenged in recent papers. In addition, signs of orbital phase dependent photometric variations, sometimes seen quite…
In this work, we analyze the ongoing brightening of the poorly studied symbiotic star V4141 Sgr and examine its long-term variability. We present new low-resolution spectroscopic observations of the system in its bright state and combine…
The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it…
The helium flash, occurring in stars of 0.6-2.0 M$_\odot$ at the end of the red giant branch, is not observable via optical means due to the energy of the process being used to lift the core out of degeneracy. Neutrinos, which are linked to…