Related papers: The Binary Fraction of Low Mass White Dwarfs
We present 594 radial velocity measurements for 71 white dwarfs obtained during our search for binary white dwarfs and not reported elsewhere. We identify three excellent candidate binaries, which require further observations to confirm our…
We describe new radial velocity and X-ray observations of extremely low-mass white dwarfs (ELM WDs, ~0.2 Msol) in the Sloan Digital Sky Survey Data Release 4 and the MMT Hypervelocity Star survey. We identify four new short period binaries,…
We present radial velocity observations of four extremely low-mass (0.2 Msol) white dwarfs. All four stars show peak-to-peak radial velocity variations of 540 - 710 km/s with 1.0 - 5.9 hr periods. The optical photometry rules out…
Knowing the masses of the components of binary systems is very useful to constrain the possible scenarios that could lead to their existence. While it is sometimes possible to determine the mass of the primary star, for single-lined…
We present the discovery of 17 low mass white dwarfs (WDs) in short-period P<1 day binaries. Our sample includes four objects with remarkable log(g)~5 surface gravities and orbital solutions that require them to be double degenerate…
White dwarfs (WDs) are powerful tools to study the evolutionary history of stars and binaries in the Galaxy. But do we understand their multiplicity from a theoretical point of view? This can be tested by a comparison with the sample of WDs…
We study a complete, colour-selected sample of double-degenerate binary systems containing extremely low mass (ELM) <0.25 Msol white dwarfs (WDs). We show, for the first time, that Milky Way disk ELM WDs have a merger rate of approximately…
Extremely low mass (ELM) white dwarfs (WDs) with masses <0.25 Msun are rare objects that result from compact binary evolution. Here, we present a targeted spectroscopic survey of ELM WD candidates selected by color. The survey is 71%…
Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical…
In recent years, approximately 150 low-mass white dwarfs (WDs), typically with masses below 0.4 solar masses, have been discovered. Observational evidence indicates that most of these low-mass WDs are found in binary systems, supporting…
Recently, a large number of low-mass (<0.30 M_sun) helium white dwarfs (He WDs) have been discovered as a result of several surveys campaigns such as WASP, ELM, Kepler or SDSS. The far majority of them have as companion another compact…
As the descendants of stars with masses less than 8 M$_{\odot}$ on the main sequence, white dwarfs provide a unique way to constrain planetary occurrence around intermediate-mass stars (spectral types BAF) that are otherwise difficult to…
Stars are stretched by tidal interactions in tight binaries, and changes to their projected areas introduce photometric variations twice per orbit. Hermes et al. (2014, ApJ, 792, 39) utilized measurements of these ellipsoidal variations to…
We present the discovery of 15 extremely low mass (5 < log{g} < 7) white dwarf candidates, 9 of which are in ultra-compact double-degenerate binaries. Our targeted ELM Survey sample now includes 76 binaries. The sample has a lognormal…
From a sample of spectra of 439 white dwarfs (WDs) from the ESO-VLT Supernova-Ia Progenitor surveY (SPY), we measure the maximal changes in radial-velocity (DRVmax) between epochs (generally two epochs, separated by up to 470d), and model…
Approximately 150 low-mass white dwarfs, with masses below 0.4Msun, have been discovered. The majority of these low-mass WDs are observed in binary systems as they cannot be formed through single-star evolution within the Hubble time. In…
Low-mass white dwarfs can either be produced in low-mass X-ray binaries by stable mass transfer to a neutron star, or in a common-envelope phase with a heavier white dwarf companion. We have searched 8 low-mass white dwarf candidates…
White dwarfs (WDs) represent the final evolutionary stage of most stars, typically originating from progenitor stars with masses below approximately 8 $M_{\odot}$ to 10 $M_{\odot}$. Formation through single-star evolution generally requires…
Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low mass white dwarf candidates serendipitously discovered in a survey for hypervelocity B-type stars.…
Measuring the masses of companions to single-line spectroscopic binary stars is (in general) not possible because of the unknown orbital plane inclination. Even when the mass of the visible star can be measured, only a lower limit can be…