scholarly journals Gravitational Redshifts for Hyades White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 378-383 ◽  
Author(s):  
G. Wegner ◽  
I. N. Reid ◽  
R. K. McMahan
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Space Velocity ◽  
Open Clusters ◽  
Galactic Clusters

Precise white dwarf gravitational redshifts can only be obtained utilizing systems of known distance and space velocity. Binaries with known orbits such as 40 Eri B are rare, and although common proper motion pairs have proven highly useful(Wegner 1973: Koester 1987: Wegner & Reid 1987), there are some problems in their interpretation. Another approach is to employ white dwarfs in open clusters; they not only have known systemic velocities, but also provide information on the progenitors of the white dwarfs. Of the nearby galactic clusters, the Hyades currently give the best information for achieving accurate gravitational redshifts: the members are relatively bright and nearby and their kinematics are well known.

scholarly journals The Initial–Final Mass Relationship of White Dwarfs in Common Proper Motion Pairs and Open Clusters

2006 ◽  
Vol 2 (S240) ◽  
pp. 380-382
Author(s):  
S. Catalán ◽  
I. Ribas ◽  
J. Isern ◽  
E. García–Berro ◽  
C. Allende Prieto
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Open Clusters ◽  
Type Star ◽  
Spectroscopic Observations ◽  
Final Mass ◽  
Semi Empirical ◽  
Relationship Of

AbstractWe have studied white dwarfs in common proper motion pairs (CPMPs) to improve the semi-empirical initial–final mass relationship of white dwarfs. In this contribution, we report new results obtained from spectroscopic observations of both members of several CPMPs composed of an F, G or K type star and a DA white dwarf.

The completeness of Gaia-selected samples of white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 170-174
Author(s):  
Terry D. Oswalt ◽  
Jay B. Holberg ◽  
Edward M. Sion
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Color Index ◽  
Apparent Magnitude ◽  
Order Of Magnitude ◽  
Gaia Dr2 ◽  
Photometric Color

AbstractThe Gaia DR2 has dramatically increased the ability to detect faint nearby white dwarfs. The census of the local white dwarf population has recently been extended from 25 pc to 50 pc, effectively increasing the sample by roughly an order of magnitude. Here we examine the completeness of this new sample as a function of variables such as apparent magnitude, distance, proper motion, photometric color index, unresolved components, etc.

scholarly journals White Dwarfs in Cataclysmic Binaries

1979 ◽  
Vol 53 ◽  
pp. 417-425 ◽  
Author(s):  
Brian Warner
Keyword(s):  
Direct Measurement ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Binary Systems ◽  
Fundamental Property ◽  
Wide Binary ◽  
Trigonometric Parallax ◽  
Select Group ◽  
Cataclysmic Binaries

For isolated stars, identification as a white dwarf may be effected in several ways. The fundamental property of abnormally low luminosity can be detected through direct measurement of trigonometric parallax or indirectly through large proper motion (accompanied by appropriate photometric properties). The presence of greatly pressure broadened absorption lines is another unambiguous criterion. Rapid light oscillations of the kind reviewed by Robinson are another hallmark of a select group of white dwarfs. Any or all of these criteria may be used to classify a star as a white dwarf and in general can be applied to members of wide binary systems.

scholarly journals On the Separations of Common Proper Motion Binaries Containing White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 454-457
Author(s):  
T.D. Oswalt ◽  
E.M. Sion
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Main Sequence ◽  
Late Type ◽  
Class A ◽  
Color Class

Luyten [1,2] and Giclas et al. [3,4] list over 500 known common proper motion binaries (CPMBs) which, on the basis of proper motion and estimated colors, are expected to contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. Preliminary assessments of the CPMBs suggest that nearly all are physical pairs [5,6]. In this paper we address the issue of whether significant orbital expansion has occurred as a consequence of the post-MS mass loss expected to accompany the formation of the WDs in CPMBs.Though the CPMB sample remains largely unobserved, a spectroscopic survey of over three dozen CPMBs by Oswalt [5] found that nearly all faint components of Luyten and Giclas color class “a-f” and “+1”, respectively, or bluer were a WD. This tendency was also evident in a smaller sample studied by Greenstein [7]. Conversely, nearly all CPMBs having two components of color class “g-k” and “+3” or redder were MS+MS pairs. With the caveat that such criteria discriminate against CPMBs containing cool (but rare) WDs, they nonetheless provide a crude means of obtaining statistically significant samples for the comparison of orbital separations: 209 highly probable WD+MS pairs and 109 MS+MS pairs.

scholarly journals The kinematics of the white dwarf population from the SDSS DR12

2017 ◽  
Vol 12 (S330) ◽  
pp. 201-202
Author(s):  
B. Anguiano ◽  
A. Rebassa-Mansergas ◽  
E. García-Berro ◽  
S. Torres ◽  
K. Freeman ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Radial Distance ◽  
Space Velocity ◽  
Galactic Disc ◽  
Present Sample ◽  
Secular Evolution ◽  
The North

AbstractWe use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalog to date, to study the evolution of the kinematical properties of the population of white dwarfs in the Galactic disc. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalog are available the true three-dimensional components of the stellar space velocity are obtained. This subset of the original sample comprises 20,247 objects, making it the largest sample of white dwarfs with measured three-dimensional velocities. Furthermore, the volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance RG = 7.8 kpc to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = −0.5 kpc to 0.5 kpc. We examine the mean components of the stellar three-dimensional velocities, as well as their dispersions with respect to the Galactocentric and vertical distances. We confirm the existence of a mean Galactocentric radial velocity gradient, ∂〈VR〉/∂RG = −3 ± 5 km s−1 kpc−1. We also confirm North-South differences in 〈Vz〉. Specifically, we find that white dwarfs with Z > 0 (in the North Galactic hemisphere) have 〈Vz〉 < 0, while the reverse is true for white dwarfs with Z < 0. The age-velocity dispersion relation derived from the present sample indicates that the Galactic population of white dwarfs may have experienced an additional source of heating, which adds to the secular evolution of the Galactic disc.

scholarly journals The Search for Brown Dwarfs around White Dwarfs

2003 ◽  
Vol 211 ◽  
pp. 289-292 ◽  
Author(s):  
J. Farihi ◽  
E. E. Becklin ◽  
B. Zuckerman
Keyword(s):  
Spectral Type ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Near Field ◽  
Brown Dwarfs ◽  
Wide Field ◽  
M Dwarfs ◽  
Recent Phase ◽  
Motion Search

The infrared search for substellar companions to nearby white dwarfs has been going on for a little more than a decade. The most recent phase has been a wide field proper motion search carried out primarily at Steward Observatory, where we are complete down to J = 18. Earlier phases included near field searches at the IRTF and Keck Observatory. In the last year we have discovered ten previously unrecognized faint proper motion companions. Of the recent discoveries, most are white dwarfs and a few M dwarfs. GD165B, discovered in 1988 as part of our program, is still the only known companion to a white dwarf with spectral type later than M.

scholarly journals 15. Cooling of White Dwarfs

1971 ◽  
Vol 42 ◽  
pp. 97-115 ◽  
Author(s):  
H. M. van Horn
Keyword(s):  
Recent Work ◽  
White Dwarf ◽  
White Dwarfs ◽  
Current Knowledge ◽  
Galactic Clusters ◽  
Precise Relationship

A knowledge of the precise relationship between the age and luminosity of a white dwarf can in principle be used to determine the compositions of the white dwarfs in galactic clusters. To this end the assumptions in Mestel's theory of white dwarf cooling are critically reviewed, and the results of recent work aimed at relaxing these restrictions are briefly summarized. It is concluded that on the basis of current knowledge an accuracy of the order of 10 or 20% in the age-luminosity relation should be attainable.

scholarly journals A catalogue of white dwarfs in Gaia EDR3

2021 ◽  
Author(s):  
N P Gentile Fusillo ◽  
P-E Tremblay ◽  
E Cukanovaite ◽  
A Vorontseva ◽  
R Lallement ◽  
...  
Keyword(s):  
Effective Temperature ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Absolute Magnitude ◽  
Sloan Digital Sky Survey ◽  
Atmospheric Models ◽  
Sky Survey ◽  
Cross Match ◽  
Temperature Surface

Abstract We present a catalogue of white dwarf candidates selected from Gaia early data release three (EDR3). We applied several selection criteria in absolute magnitude, colour, and Gaia quality flags to remove objects with unreliable measurements while preserving most stars compatible with the white dwarf locus in the Hertzsprung-Russell diagram. We then used a sample of over 30 000 spectroscopically confirmed white dwarfs and contaminants from the Sloan Digital Sky Survey (SDSS) to map the distribution of these objects in the Gaia absolute magnitude-colour space. Finally, we adopt the same method presented in our previous work on Gaia DR2 to calculate a probability of being a white dwarf (PWD) for ≃ 1.3 million sources which passed our quality selection. The PWD values can be used to select a sample of ≃ 359 000 high-confidence white dwarf candidates. We calculated stellar parameters (effective temperature, surface gravity, and mass) for all these stars by fitting Gaia astrometry and photometry with synthetic pure-H, pure-He and mixed H-He atmospheric models. We estimate an upper limit of 93 per cent for the overall completeness of our catalogue for white dwarfs with G ≤ 20 mag and effective temperature (Teff) &gt;7000 K, at high Galactic latitudes (|b| &gt; 20○). Alongside the main catalogue we include a reduced-proper-motion extension containing ≃ 10 200 white dwarf candidates with unreliable parallax measurements which could, however be identified on the basis of their proper motion. We also performed a cross-match of our catalogues with SDSS DR16 spectroscopy and provide spectral classification based on visual inspection for all resulting matches.

scholarly journals 4. Trigonometrical Parallaxes of LB 3303 and LB 3459

1971 ◽  
Vol 42 ◽  
pp. 21-23 ◽  
Author(s):  
J. Churms ◽  
A. D. Thackeray
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs

Radcliffe spectra of this star in 1961 confirmed Luyten's suspicion on the basis of colour and proper motion that this object is a bright white dwarf. The profile of Hγ was found to be closely similar to that of o2 Eri B. Hill and Hill have published photometry yielding V = 11.40. The only known white dwarfs brighter than this are Sirius B, o2 Eri B, Procyon B, Feige 34 and CD −38° 10980.

scholarly journals Effective Temperatures of White Dwarfs

1970 ◽  
Vol 7 ◽  
pp. 96-102
Author(s):  
J. B. Oke
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Proper Motions ◽  
Stellar Astronomy ◽  
Effective Temperatures ◽  
Motion Studies ◽  
Work Done

Of all the fields of stellar astronomy, the study of white dwarfs has been most influenced by work done on proper motions. From proper motion studies, particularly by Luyten and Giclas in recent years, many white dwarf candidates have been found. These candidates have been studied intensively, particularly by Greenstein who has obtained spectra and Eggen who has measured magnitude and colors. As a result, many new white dwarfs have been discovered, and we now have many examples of most types of white dwarfs. It is, therefore, possible to study each group separately and to find relationships between the various types of white dwarfs.

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