J/ApJ/889/49 The ELM Survey. VIII. Final double WD binaries (Brown+, 2020)
The ELM Survey.
VIII. Ninety-eight double white dwarf binaries.
Brown W.R., Kilic M., Kosakowski A., Andrews J.J., Heinke C.O.,
Agueros M.A., Camilo F., Gianninas A., Hermes J.J., Kenyon S.J.
<Astrophys. J., 889, 49-49 (2020)>
=2020ApJ...889...49B 2020ApJ...889...49B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple; Stars, white dwarf; Spectra, optical;
Radial velocities; Stars, masses; Stars, distances; Proper motions
Keywords: White dwarf stars; Compact binary stars; Galaxy stellar content
Abstract:
We present the final sample of 98 detached double white dwarf (WD)
binaries found in the Extremely Low Mass (ELM) Survey, a spectroscopic
survey targeting <0.3M☉ He-core WDs completed in the Sloan
Digital Sky Survey footprint. Over the course of the survey we
observed ancillary low-mass WD candidates like GD 278, which we show
is a P=0.19d double WD binary, as well as candidates that turn out to
be field blue straggler/subdwarf A-type stars with luminosities too
high to be WDs given their Gaia parallaxes. Here, we define a clean
sample of ELM WDs that is complete within our target selection and
magnitude range 15<g0<20mag. The measurements are consistent with
100% of ELM WDs being 0.0089<P<1.5d double WD binaries, 35% of which
belong to the Galactic halo. We infer that these are mostly He+CO WD
binaries given the measurement constraints. The merger rate of the
observed He+CO WD binaries exceeds the formation rate of stable
mass-transfer AM CVn binaries by a factor of 25, and so the majority
of He+CO WD binaries must experience unstable mass transfer and merge.
The systems with the shortest periods, such as J0651+2844, are
signature LISA verification binaries that can be studied with
gravitational waves and light.
Description:
We observed a total of 230 low-mass WD candidates with >3 spectroscopic
observations.
Most of our spectroscopy was obtained with the 6.5m MMT telescope and
the Blue Channel spectrograph.
We also acquired time-series spectra for the brightest g<17mag objects
at the 1.5m Fred Lawrence Whipple Observatory (FLWO) telescope with
the FAST spectrograph, and starting in 2017, the 4.1m Southern
Astrophysical Research (SOAR) telescope using the Goodman High
Throughput spectrograph.
For purposes of completeness, we also include radial velocity
measurements acquired at the 8m Gemini telescopes with GMOS and the 4m
Mayall telescope using the Kitt Peak Ohio State Multi-Object
Spectrograph.
See Section 2.3.
We engaged in a long-term radio campaign using the Robert C. Byrd
Green Bank Telescope (GBT) to target ELM WD candidates with the
highest minimum companion masses. The results from semesters
GBT/05C-041, GBT/06A-051, GBT/07C-072, and GBT/10A-046 are previously
published (Agueros+ 2009ApJ...697..283A 2009ApJ...697..283A & 2009ApJ...700L.123A 2009ApJ...700L.123A and
Kilic+ 2013MNRAS.434.3582K 2013MNRAS.434.3582K). Here, we report the results for the 20
candidates observed in the semesters GBT/12A-431 and GBT/14A-438. The
20 candidates were published in previous ELM Survey papers, but their
radio observations were not. See Section 3.3.1.
We obtained Chandra X-ray Observatory observations for 10 low-mass ELM
candidates. Eight are previously published (Kilic+ 2013MNRAS.434.3582K 2013MNRAS.434.3582K ;
2014MNRAS.438L..26K 2014MNRAS.438L..26K and 2016MNRAS.460.4176K 2016MNRAS.460.4176K). We present the results
for the final 2 candidates with Chandra observations, J0147+0113 and
J2245+0750 here. See Section 3.3.2.
Finally, we obtained time-series optical photometry for the newly
discovered P=0.048d WD binary J1738+2927 on UT 2018 May 16. We
acquired images using the Agile frame-transfer camera and the BG40
filter on the 3.5m telescope at the Apache Point Observatory (APO).
See Section 3.4.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 39 4338 Radial velocity measurements
table2.dat 189 230 Measured and derived parameters
table3.dat 105 128 Binary parameters
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See also:
B/psr : ATNF Pulsar Catalogue (Manchester+, 2005)
III/129 : Spectroscopically Identified White Dwarfs (McCook+, 1987)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
II/350 : VLT Survey Telescope ATLAS (Shanks+, 2015)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
I/343 : Gaia-PS1-SDSS (GPS1) proper motion catalog (Tian+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
I/351 : The extended Gaia-PS1-SDSS (GPS1+) proper motion cat. (Tian+, 2020)
J/MNRAS/287/867 : Edinburgh-Cape Blue Object Survey. Zone 1. (Kilkenny+ 1997)
J/ApJ/647/303 : Spectroscopic survey of hypervelocity stars (Brown+, 2006)
J/ApJS/167/40 : SDSS4 confirmed white dwarfs catalog (Eisenstein+, 2006)
J/MNRAS/382/1377 : SDSS WD main-sequence binaries (Rebassa-Mansergas+, 2007)
J/MNRAS/402/620 : SDSS WD main-sequence binaries (Rebassa-Mansergas+, 2010)
J/ApJ/723/1072 : The ELM survey. I. Low-mass white dwarfs (Brown+, 2010)
J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)
J/A+A/536/A43 : SDSS WD main-sequence bin. XII. (Nebot Gomez-Moran+, 2011)
J/ApJ/743/138 : Spectroscopic survey of bright WDs (Gianninas+, 2011)
J/ApJ/751/55 : MMT hypervelocity star survey. II. (Brown+, 2012)
J/ApJS/204/5 : SDSS DR7 white dwarf catalog (Kleinman+, 2013)
J/MNRAS/429/2143 : Hidden population of AM CVns in the SDSS (Carter+, 2013)
J/A+A/557/A19 : Mass & age of extreme low-mass white dwarfs (Althaus+, 2013)
J/ApJ/794/35 : Binary WDs atmospheric parameters (Gianninas+, 2014)
J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015)
J/ApJ/812/167 : The ELM survey. VI. 11 new ELM WD bin. (Gianninas+, 2015)
J/ApJ/818/155 : The ELM survey. VII. 15 new ELM WD cand. (Brown+, 2016)
J/MNRAS/455/3413 : New WD and subdwarf stars in SDSS DR12 (Kepler+, 2016)
J/A+A/595/A35 : Low-mass helium WDs evolutionary models (Istrate+, 2016)
J/ApJ/839/23 : Subdwarf A stars vs ELM WDs radial velocities (Brown+, 2017)
J/MNRAS/471/4218 : 4 low-mass white-dwarf candidates velocities (Kilic+, 2017)
J/MNRAS/472/4173 : Bright white dwarfs for high-speed photometry (Raddi+, 2017)
J/MNRAS/475/2480 : Extremely-low mass white dwarf star (Pelisoli+, 2018)
J/A+A/617/A6 : Seven new pulsating sdA stars (Bell+, 2018)
J/A+A/638/A131 : Radial velocities of 643 DA white dwarfs (Napiwotzki+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier (JHHMM+DDMM)
12- 25 F14.9 d HJD Heliocentric Julian Date; JD-2450000
27- 33 F7.2 km/s HRV [-600/697] Heliocentric radial velocity
35- 39 F5.2 km/s e_HRV [2/84] Uncertainty in HRV
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier (JHHMM+DDMM)
12- 13 I2 h RAh Hour of Right Ascension (J2000)
15- 16 I2 min RAm Minute of Right Ascension (J2000)
18- 23 F6.3 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of Declination (J2000)
38- 43 F6.3 mag gmag [12.7/20.6] Apparent g band magnitude;
dereddened (1)
45- 49 F5.3 mag e_gmag [0.003/0.1] Uncertainty in gmag
51- 55 I5 K Teff [6679/37250] Effective temperature (2)
57- 59 I3 K e_Teff [90/570] Uncertainty in Teff
61- 65 F5.3 [cm/s2] log(g) [4.6/8.1] log surface gravity (2)
67- 71 F5.3 [cm/s2] e_log(g) [0.04/0.4] Uncertainty in log(g)
73 I1 --- WD White dwarf flag (1=True; 122 occurrences)
75 I1 --- ELM ELM white dwarf flag (1=True; 79 occurrences)
77 I1 --- Clean ELM white dwarf in clean sample (1=True;
62 occurrences)
79 I1 --- Disk ? Object that orbits in the disk (1=True;
81 occurrences)
81- 85 F5.3 Msun Mass [0.14/0.7] Mass (3)
87- 91 F5.3 Msun e_Mass [0.01/0.05] Uncertainty in Mass
93- 97 F5.2 mag gMag [4.6/11.3] Absolute g band magnitude (3)
99-102 F4.2 mag e_gMag [0.03/1] Uncertainty in gMag
104-109 F6.3 kpc Dist [0.08/10.3] Heliocentric distance (3)
111-115 F5.3 kpc e_Dist [0.006/4] Uncertainty in Dist
117-123 F7.4 mas plx [-0.8/13]? Parallax (4)
125-132 F8.4 mas e_plx [0.03/1.6]? Uncertainty in plx
134-142 F9.4 mas/yr pmRA [-132/235] Proper motion along RA (4)
144-151 F8.4 mas/yr e_pmRA [0.04/5] Uncertainty in pmRA
153-161 F9.4 mas/yr pmDE [-179/51] Proper motion along DE (4)
163-168 F6.4 mas/yr e_pmDE [0.04/5] Uncertainty in pmDE
171-189 I19 --- Gaia Gaia DR2 source identifier
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Note (1): From SDSS except for 5 cases when it is derived from PanStarrs g or
Gaia G.
Note (2): Corrected for 3D effects following Tremblay+ (2015ApJ...809..148T 2015ApJ...809..148T).
Note (3): Derived using the models of Althaus+ (2013A&A...557A..19A 2013A&A...557A..19A) and
Istrate+ (2016A&A...595A..35I 2016A&A...595A..35I), but are only valid for objects marked
WD=1.
Note (4): For the eight candidates without Gaia 5-parameter solutions, we list
proper motions from Gaia-PanStarrs1 (Tian+ 2017, I/343)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier (JHHMM+DDMM)
12- 13 I2 --- Nobs [5/78] Number of spectroscopic observations
15- 21 F7.5 d Per [0.0088/1.6] Binary orbital period
23- 29 F7.5 d e_Per [1e-5/0.11] Uncertainty in Per
31- 35 F5.1 km/s K [26/618] Radial velocity semi-amplitude
37- 41 F5.1 km/s e_K [1/115] Uncertainty in K
43- 48 F6.1 km/s gamma [-352/199] Systemic velocity corrected for
gravitational redshift
50- 54 F5.1 km/s e_gamma [1.6/161] Uncertainty in gamma
56- 59 F4.2 Msun M2 [0.02/2.3] Minimum secondary mass
61- 65 F5.2 [yr] logtau [6/12.7] log maximum gravitational merger
timescale
67- 67 I1 --- Alias? [0/1] Binary with a significant period
alias (1=True)
69- 76 F8.2 --- Delchi2 [0/11372] The χ2 at Palias relative
to the global χ2 minimum
78- 84 F7.5 d Palias [0.0098/1.82] Period of the alias
86- 91 F6.2 10-21 Strain [0.17/160]? Characteristic strain times the
S/N boost (1)
93- 98 F6.2 10-21 E_Strain [0.05/138]? The 84.1% uncertainty in Strain
100-105 F6.2 10-21 e_Strain [0.04/45]? The 15.9% uncertainty in Strain
--------------------------------------------------------------------------------
Note (1): Where Strain=hc (the Characteristic strain) times ((4yr)*f)0.5
(S/N boost from the number of cycles during the LISA observation
time; the values plotted in Figure 10).
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History:
From electronic version of the journal
References:
Brown et al. Paper I. 2010ApJ...723.1072B 2010ApJ...723.1072B Cat. J/ApJ/723/1072
Kilic et al. Paper II. 2011ApJ...727....3K 2011ApJ...727....3K
Brown et al. Paper III. 2012ApJ...744..142B 2012ApJ...744..142B
Kilic et al. Paper IV. 2012ApJ...751..141K 2012ApJ...751..141K
Brown et al. Paper V. 2013ApJ...769...66B 2013ApJ...769...66B Cat. J/ApJ/769/66
Gianninas et al. Paper VI. 2015ApJ...812..167G 2015ApJ...812..167G Cat. J/ApJ/812/167
Brown et al. Paper VII. 2016ApJ...818..155B 2016ApJ...818..155B Cat. J/ApJ/818/155
Brown et al. Paper VIII. 2020ApJ...889...49B 2020ApJ...889...49B This catalog
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Jul-2021