Related papers: A magnetic white dwarf formed through a binary mer…
There is a striking and unexplained dearth of brown dwarf companions in close orbits (< 3AU) around stars more massive than the Sun, in stark contrast to the frequency of stellar and planetary companions. Although rare and relatively…
The formation channels and predicted populations of double-white dwarfs (DWDs) are important because a subset will evolve to be gravitational-wave sources and/or progenitors of Type Ia supernovae. Given the observed population of…
Using the Zwicky Transient Facility (ZTF), Burdge et al. (2020) discovered systems of eclipsing double white dwarfs (EDWDs) having orbital periods <1 hr. From the properties of 3 of the discovered systems, I estimate a merger rate of DWDs,…
Binary systems of a hot subdwarf B (sdB) star + a white dwarf (WD) with orbital periods less than 2-3 hours can come into contact due to gravitational waves and transfer mass from the sdB star to the WD before the sdB star ceases nuclear…
The Hubble Space Telescope observation of the double white dwarf (WD) binary SDSS J125733.63$+$542850.5 reveal that the massive WD has a surface gravity log$g_1\sim8.7$ (which implies a mass of $M_1\sim1.06~{\rm M_\odot}$) and an effective…
White dwarf stars have been used for decades as precise and accurate age indicators. This work presents a test of the reliability of white dwarf total ages when spectroscopic observations are available. We conduct follow-up spectroscopy of…
White dwarf (WD) binary mergers are possible progenitors to a number of unusual stars and transient phenomena, including type Ia supernovae. To date, simulations of mergers have not included magnetic fields, even though they are believed to…
We study the full evolution of a 1.313 Msun white dwarf star that descended from a 9 Msun main-sequence progenitor with an initial metallicity of Z=0.02. Using MESA r24.08.01, we calculate its entire evolution from pre-ZAMS to the WD…
Polluted white dwarfs are generally accreting terrestrial-like material that may originate from a debris belt like the asteroid belt in the solar system. The fraction of white dwarfs that are polluted drops off significantly for white…
White dwarfs are the burnt out cores of Sun-like stars and are the final fate of 97% of all stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements, apart…
Magnetic fields generated by a dynamo mechanism due to differential rotation during stellar mergers are often proposed as an explanation for the presence of strong fields in certain classes of magnetic stars, including high field magnetic…
More than half of all main-sequence (MS) stars have one or more companions, and many of those with initial masses <8 M$_\odot$ are born in hierarchical triples. These systems feature two stars in a close orbit (the inner binary) while a…
Magnitude-limited samples have shown that 20-25 per cent of cataclysmic variables contain white dwarfs with magnetic fields of Mega Gauss strength, in stark contrast to the approximately 5 per cent of single white dwarfs with similar…
Low mass white dwarfs are the remnants of disrupted red giant stars in binary millisecond pulsars and other exotic binary star systems. Some low mass white dwarfs cool rapidly, while others stay bright for millions of years due to stable…
Low-mass white dwarfs (LMWDs) are believed to be exclusive products of binary evolution, as the Universe is not yet old enough to produce them from single stars. Because of the strong tidal forces operating during the binary interaction…
Low-mass helium-core white-dwarfs (WDs) with masses below 0.5 Msun are known to be formed in binary star systems but unexpectedly a significant fraction of them seem to be single. On the other hand, in Cataclysmic Variables (CVs) a large…
Many white dwarfs are observed in compact double white dwarf binaries and, through the emission of gravitational waves, a large fraction are destined to merge. The merger remnants that do not explode in a Type Ia supernova are expected to…
Ultramassive white dwarfs with masses $M\gtrsim 1.1\,{\rm M}_\odot$ probe extreme physics near the Chandrasekhar limit. Despite the rapid increase in observations, it is still unclear how many harbour carbon-oxygen (CO) versus oxygen-neon…
Today, Type Ia supernovae are essential tools for cosmology, and recognized as major contributors to the chemical evolution of galaxies. The construction of detailed supernova progenitor models, however, was so far prevented by various…
We present new observations of very faint white dwarfs (WDs) in the rich open star cluster NGC 2099 (M37). Following deep, wide field imaging of the cluster using CFHT, we have now obtained spectroscopic observations of candidate WDs using…