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 Gaia white dwarfs within 40 pc II: the volume-limited Northern hemisphere sample

2020 ◽  
Vol 499 (2) ◽  
pp. 1890-1908 ◽  
Author(s):  
Jack McCleery ◽  
Pier-Emmanuel Tremblay ◽  
Nicola Pietro Gentile Fusillo ◽  
Mark A Hollands ◽  
Boris T Gänsicke ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Mass Range ◽  
Wide Binary ◽  
William Herschel ◽  
Initial Selection ◽  
Gaia Dr2 ◽  
Kinematic Properties

ABSTRACT 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 identified as white dwarf candidates from Gaia DR2 and followed up recently with the William Herschel Telescope and Gran Telescopio Canarias. Three additional white dwarf candidates remain spectroscopically unobserved and six unresolved binaries are known to include a white dwarf but were not in our initial selection in the Gaia DR2 Hertzsprung–Russell diagram. Atmospheric parameters are calculated from Gaia and Pan-STARRS photometry for all objects in the sample, confirming most of the trends previously observed in the much smaller 20 pc sample. Local white dwarfs are overwhelmingly consistent with Galactic disc kinematics, with only four halo candidates. We find that DAZ white dwarfs are significantly less massive than the overall DA population ($\overline{M}_\mathrm{DAZ}$ = 0.59 M⊙, $\overline{M}_\mathrm{DA}$ = 0.66 M⊙). It may suggest that planet formation is less efficient at higher mass stars, producing more massive white dwarfs. We detect a sequence of crystallized white dwarfs in the mass range from 0.6 $\lesssim M/\mbox{$\mathrm{M}_\odot $}\ \lesssim$ 1.0 and find that the vast majority of objects on the sequence have standard kinematic properties that correspond to the average of the sample, suggesting that their nature can be explained by crystallization alone. We also detect 26 double degenerates and white dwarf components in 56 wide binary systems.

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.

scholarly journals A new white dwarf companion around the Δμ star GJ 3346

2020 ◽  
Vol 494 (3) ◽  
pp. 3481-3490
Author(s):  
M Bonavita ◽  
C Fontanive ◽  
S Desidera ◽  
V D’Orazi ◽  
A Zurlo ◽  
...  
Keyword(s):  
Effective Temperature ◽  
White Dwarf ◽  
Proper Motion ◽  
Main Sequence ◽  
Archival Data ◽  
Data Sets ◽  
Selection Methods ◽  
Open Time ◽  
Substellar Companions ◽  
Gaia Dr2

ABSTRACT We present the discovery of a white dwarf companion at ∼3.6 arcsec from GJ 3346, a nearby (π ∼ 42 mas) K star observed with SPHERE@VLT as part of an open time survey for faint companions to objects with significant proper motion discrepancies (Δμ) between Gaia DR1 and Tycho-2. Syrius-like systems like GJ 3346 AB, which include a main-sequence star and a white dwarf, can be difficult to detect because of the intrinsic faintness of the latter. They have, however, been found to be common contaminants for direct imaging (DI) searches. White dwarfs have in fact similar brightness to substellar companions in the infrared, while being much brighter in the visible bands like those used by Gaia. Combining our observations with Gaia DR2 and with several additional archival data sets, we were able to fully constrain the physical properties of GJ 3346 B, such as its effective temperature (11 × 103 ± 500 K) as well as the cooling age of the system (648 ± 58 Myr). This allowed us to better understand the system history and to partially explain the discrepancies previously noted in the age indicators for this object. Although further investigation is still needed, it seems that GJ 3346, which was previously classified as young, is in fact most likely to be older than 4 Gyr. Finally, given that the mass (0.58 ± 0.01 M⊙) and separation (85 au) of GJ 3346 B are compatible with the observed Δμ, this discovery represents a further confirmation of the potential of this kind of dynamical signatures as selection methods for DI surveys targeting faint, substellar companions.

scholarly journals A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455−282, WD0621−376, and WD2211−495

2019 ◽  
Vol 487 (3) ◽  
pp. 3470-3487 ◽  
Author(s):  
Simon P Preval ◽  
Martin A Barstow ◽  
Matthew Bainbridge ◽  
Nicole Reindl ◽  
Thomas Ayres ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Hubble Space Telescope ◽  
Line Of Sight ◽  
Hot Metal ◽  
Dwarf Stars ◽  
High Resolution Data ◽  
White Dwarf Stars ◽  
Order Of Magnitude ◽  
Far Ultraviolet

ABSTRACT Using newly obtained high-resolution data (R ∼ 1 × 105) from the Hubble Space Telescope, and archival UV data from the Far Ultraviolet Spectroscopic Explorer, we have conducted a detailed UV survey of the three hot, metal-polluted white dwarfs WD0455−282, WD0621−376, and WD2211−495. Using bespoke model atmospheres, we measured Teff, log g, and photospheric abundances for these stars. In conjunction with data from Gaia, we measured masses, radii, and gravitational redshift velocities for our sample of objects. We compared the measured photospheric abundances with those predicted by radiative levitation theory, and found that the observed Si abundances in all three white dwarfs, and the observed Fe abundances in WD0621−376 and WD2211−495, were larger than those predicted by an order of magnitude. These findings imply not only an external origin for the metals, but also ongoing accretion, as the metals not supported by radiative levitation would sink on extremely short time-scales. We measured the radial velocities of several absorption features along the line of sight to the three objects in our sample, allowing us to determine the velocities of the photospheric and interstellar components along the line of sight for each star. Interestingly, we made detections of circumstellar absorption along the line of sight to WD0455−282 with three velocity components. To our knowledge, this is the first such detection of multicomponent circumstellar absorption along the line of sight to a white dwarf.

scholarly journals Gaia DR2 white dwarfs in the Hercules stream

2019 ◽  
Vol 629 ◽  
pp. L6 ◽  
Author(s):  
Santiago Torres ◽  
Carles Cantero ◽  
María E. Camisassa ◽  
Teresa Antoja ◽  
Alberto Rebassa-Mansergas ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Age Distribution ◽  
Thick Disk ◽  
Velocity Space ◽  
Dwarf Stars ◽  
The Past ◽  
White Dwarf Stars ◽  
Dynamic Variables ◽  
Gaia Dr2

Aims. We analyzed the velocity space of the thin- and thick-disk Gaia white dwarf population within 100 pc by searching for signatures of the Hercules stellar stream. We aimed to identify objects belonging to the Hercules stream, and by taking advantage of white dwarf stars as reliable cosmochronometers, to derive a first age distribution. Methods. We applied a kernel density estimation to the UV velocity space of white dwarfs. For the region where a clear overdensity of stars was found, we created a 5D space of dynamic variables. We applied a hierarchichal clustering method, HDBSCAN, to this 5D space, and identified those white dwarfs that share similar kinematic characteristics. Finally, under general assumptions and from their photometric properties, we derived an age estimate for each object. Results. The Hercules stream was first revealed as an overdensity in the UV velocity space of the thick-disk white dwarf population. Three substreams were then found: Hercules a and Hercules b, formed by thick-disk stars with an age distribution that peaked 4 Gyr in the past and extends to very old ages; and Hercules c, with a ratio of 65:35 of thin to thick stars and a more uniform age distribution that is younger than 10 Gyr.

Testing white dwarf cosmochronology using wide double white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 197-201
Author(s):  
Tyler Heintz ◽  
JJ Hermes
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Mass Relation ◽  
Final Mass ◽  
Gaia Dr2

AbstractWe present a sample of nearly 650 widely separated double white dwarf binaries found using Gaia DR2 astrometry. We derive preliminary total ages for each white dwarf in our sample using Gaia photometry and compare the total ages of both components of each binary in our sample. We find agreement within 3 sigma between the two ages ∼85% of the time with median age uncertainties of ∼3.5 Gyr depending on which initial-final mass relation is used. When a subsample with the most precise ages is used, the agreement within 3 sigma drops to ∼70% with median age uncertainties of 300-600 Myr.

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 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) >7000 K, at high Galactic latitudes (|b| > 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.

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