Related papers: Novae Ejecta as Discrete Adiabatically Expanding G…
A helium nova occurs on a white dwarf (WD) accreting hydrogen-deficient matter from a helium star companion. When the mass of a helium envelope on the WD reaches a critical value, unstable helium burning ignites to trigger a nova outburst.…
In this work, optical observations of the nova V5584 Sgr are presented. These observations cover different phases including pre-maximum, early decline, and nebular. The spectra are dominated by hydrogen Balmer, Fe II, and O I lines with…
Thermonuclear supernovae (SNe) are the result of the nuclear transformation of carbon/oxygen (C/O) white dwarfs (WDs) to the radioactive element $^{56}\mathrm{Ni}$ and intermediate mass elements (IMEs) like Ca, Ar, etc. Most progenitor…
We propose a method to identify the companion stars of type Ia supernovae (SNe Ia) in young supernova remnants (SNRs) by recognizing distinct features of absorption lines due to Fe I appearing in the spectrum. If a sufficient amount of Fe I…
Classical novae are among the most frequent transient events in the Milky Way, and key agents of ongoing nucleosynthesis. Despite their large numbers, they have never been observed in soft $\gamma$-ray emission. Measurements of their…
A high-resolution spectroscopic survey of postoutburst novae reveals short-lived heavy element absorption systems in a majority of novae near maximum light, having expansion velocities of 400-1000 km/s and velocity dispersions between…
We present observations of the unusual optical transient SN 2010U, including spectra taken 1.03 days to 15.3 days after maximum light that identify it as a fast and luminous Fe II type nova. Our multi-band light curve traces the fast…
Quark-novae leave behind quark stars with a surrounding metal-rich fall-back (ring-like) material. These compact remnants have high magnetic fields and are misconstrued as magnetars; however, several observational features allow us to…
Multiwavelength radiation from relativistic particles accelerated at shocks in novae and other astrophysical sources carries a wealth of information about the outflow properties and the microphysical processes at work near the shocks. The…
Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these…
The optical spectroscopic observations of ASASSN-18fv observed from 2018 March 24 to 2019 Jan 26 are presented. The optical spectra are obtained from Mirranook, Vainu Bappu and South African Astronomical observatories. The spectra are…
The Fermi LAT discovery that classical novae produce >100 MeV gamma-rays establishes that shocks and relativistic particle acceleration are key features of these events. These shocks are likely to be radiative due to the high densities of…
Classical and recurrent nova explosions occur on top of white dwarfs accreting H-rich matter from a companion main sequence or red giant star, in a close binary system. In the recent years, since the launch of the Fermi gamma-ray satellite…
Using a hybrid binary population synthesis approach, we modelled the formation and evolution of populations of accreting WDs for differing star formation histories. We found that the delay time distribution of SNe Ia in the single…
There is a wide consensus in the astrophysics community that the mechanism underlying the observed Classical Nova eruptions is a surface thermonuclear runaway. We start this short review with the main observational facts that lead to the…
The hydrogen-rich envelopes accreted by white dwarf stars from their red dwarf companions lead to thermonuclear runaways observed as classical nova eruptions peaking at up to 1 Million solar luminosities. Virtually all nova progenitors are…
It has been suggested that most Be/X-ray binaries are low X-ray luminosity nearby objects, containing white dwarfs (Chevalier & Ilovaisky 1998). We show that existing evidence indicates that all known Be/X-ray binaries are relatively bright…
We show that several features reminiscent of short-hard Gamma-ray Bursts (GRBs) arise naturally when Quark-Novae occur in low-mass X-ray binaries born with massive neutron stars (> 1.6M_sun) and harboring a circumbinary disk. Near the end…
The 135 classical novae that we have discovered in M87 with two $\textit{Hubble Space Telescope}$ imaging surveys appear to be strongly concentrated along that galaxy's jet. Detailed simulations show that the likelihood that this…
We present the results of a systematic analysis of a group of Type II plateau supernovae that span a large range in luminosities, from faint objects like SN 1997D and 1999br to very luminous events like SN 1992am. The physical properties of…