相关论文: The non-explosive stellar merging origin of the ul…
We present a spectro-photometric analysis of 2880 cool white dwarfs within 100 pc of the Sun and cooler than Teff = 10,000 K, with grizy Pan-STARRS photometry and Gaia trigonometric parallaxes available. We also supplement our data sets…
This paper reports a Galactic kinematical and dynamical analysis of 1003 main-sequence carbon stars. The sample is drawn from the Sloan Digital Sky Survey, and cross-matched with Gaia DR3 to obtain 6-dimensional positions and velocities…
Merger of a white dwarf binary creates a differentially rotating object which is expected to generate strong magnetic fields. Kinetic energy stored in differential rotation is partially dissipated in the magnetically dominated corona, which…
We report on studies of Classical Nova (CN) explosions where we follow the evolution of thermonuclear runaways (TNRs) on Carbon Oxygen (CO) white dwarfs (WDs). We vary both the mass of the WD (from 0.6 M$_\odot$ to 1.35 M$_\odot$) and the…
The present paper focuses on the evolution of hydrogen-deficient white dwarfs with the aim of exploring the consequences of different initial envelope structures on the carbon abundances expected in helium-rich, carbon-contaminated DQ white…
The origin of magnetic white dwarfs (MWDs) has been a long-standing puzzle. Proposed origin mechanisms have included: fossil fields frozen in from the progenitor convective core; a dynamo in the progenitor envelope; crystallization dynamos…
We investigate whether the recently-observed population of high-velocity white dwarfs can be derived from a population of binaries residing initially within the thin disk of the Galaxy. In particular we consider binaries where the primary…
Binaries of two white dwarfs (WDs) are an important class of astrophysical objects that are theorized to lead to Type Ia supernovae and are also used to gain insight into complex processes involved in stellar binary evolution. We report the…
The first solids that form as a cooling white dwarf (WD) starts to crystallize are expected to be greatly enriched in actinides. This is because the melting points of WD matter scale as $Z^{5/3}$ and actinides have the largest charge $Z$.…
The surface abundances of extreme helium (EHe) and R Coronae Borealis (RCB) stars are discussed in terms of the merger of a carbon-oxygen white dwarf with a helium white dwarf. The model is expressed as a linear mixture of the individual…
The progenitors of Type Ia Supernovae (SNe Ia) are still unknown, despite significant progress during the last years in theory and observations. Violent mergers of two carbon--oxygen (CO) white dwarfs (WDs) are one candidate suggested to be…
Seismological observations with the Whole Earth Telescope (WET) allow the determination of the subsurface compositional structure of white dwarf stars. The hot DO PG 1159 has a helium surface layer with a mass of 0.001 Msun, while the…
Early excess emission observed in Type Ia supernovae (SNe Ia) within $\sim1$ day of explosion provides a critical window into their progenitor systems. In the present study, we investigate formation of the circumstellar matter (CSM) in…
Optical spectroscopic observations of white dwarf stars selected from catalogs based on the Gaia DR2 database reveal nine new gaseous debris disks that orbit single white dwarf stars, about a factor of two increase over the previously known…
The mass function of hydrogen-rich atmosphere white dwarfs has been frequently found to reveal a distinctive high-mass excess near 1Msun. However, a significant excess of massive white dwarfs has not been detected in the mass function of…
Hydrogen deficient stars include the cool R CrB variable (RCBs) and hydrogen-deficient carbon (HdCs) giants through extreme helium stars (EHes) to the very hot helium-rich subdwarfs (He-sdO and O(He) stars) and white dwarfs. With surfaces…
We present an overview of the sample of northern hemisphere white dwarfs within 40 pc of the Sun detected from $Gaia$ Data Release 2 (DR2). We find that 521 sources are spectroscopically confirmed degenerate stars, 111 of which were first…
Galaxy mergers are pivotal events in the evolutionary history of galaxies, with their impact believed to be particularly significant in dwarf galaxies. We report the serendipitous identification of an isolated merging dwarf system with a…
Doubly-degenerate binary systems consisting of two white dwarfs both composed of carbon and oxygen and close enough that mass is transferred from the less massive to the more massive are possible progenitors of type Ia supernovae. If the…
White dwarfs and neutron stars are stellar objects with masses comparable to that of our sun. However, as the endpoint stages of stellar evolution, these objects do not sustain any thermonuclear burning and therefore can no longer support…