J/ApJ/933/94 The ELM survey. IX. Low-mass SDSS+Gaia WD binaries (Brown+, 2022)
The ELM survey.
IX. A complete sample of low-mass white dwarf binaries in the SDSS footprint.
Brown W.R., Kilic M., Kosakowski A., Gianninas A.
<Astrophys. J., 933, 94 (2022)>
=2022ApJ...933...94B 2022ApJ...933...94B
ADC_Keywords: Stars, white dwarf ; Stars, double and multiple ;
Spectra, optical ; Radial velocities ; Stars, masses ;
Effective temperatures ; Stars, distances; Colors
Keywords: Compact binary stars ; White dwarf stars ; DA stars
Abstract:
We present the discovery of 17 double white dwarf (WD) binaries from
our ongoing search for extremely low mass (ELM) <0.3M☉ WDs,
objects that form from binary evolution. Gaia parallax provides a new
means of target selection that we use to evaluate our original ELM
Survey selection criteria. Cross-matching the Gaia and Sloan Digital
Sky Survey (SDSS) catalogs, we identify an additional 36 ELM WD
candidates with 17<g<19mag and within the 3σ uncertainties of
our original color selection. The resulting discoveries imply the ELM
Survey sample was 90% complete in the color range -0.4<(g-r)0←0.1mag
(approximately 9000K<Teff<22000K). Our observations complete the
sample in the SDSS footprint. Two newly discovered binaries,
J123950.370-204142.28 and J232208.733+210352.81, have orbital periods
of 22.5 and 32 minutes, respectively, and are future Laser
Interferometer Space Antenna gravitational-wave sources.
Description:
We use Gaia -DR2 and -eDR3 and SDSS DR16 multipassband photometry to
identify extremely low mass (ELM) white dwarf (WD) candidates.
Fifty-seven objects jointly satisfy the Gaia eDR3 parallax and SDSS
color selection criteria with 17<g<19mag. These objects are the
highest-probability ELM WD candidates in the SDSS footprint.
Table 1 presents the list of all selected candidates.
See Section 2.
Our observational strategy is to obtain a spectrum for each target,
and then follow-up likely ELM WDs with time-series spectroscopy. We
began observations in late 2018 after the release of Gaia DR2.
We obtained spectra for all 39 of the previously unobserved objects at
the 6.5m MMT telescope with the Blue Channel spectrograph
(3550-4500Å coverage at 1.2Å spectral resolution).
For seven southern targets, we obtained additional spectra at the 6.5m
Magellan telescope with the MagE spectrograph (R=4800) and at the 4.1m
SOAR telescope with the Goodman High Throughput spectrograph (spectral
resolution of 2.5Å). SOAR observations were obtained as part of the
NOAO Programs 2019A-0134 and 2021A-0007.
We also obtained time-series spectroscopy of J010128.690+040159.00 at
the Apache Point Observatory 3.5m telescope with the Dual Imaging
Spectrograph (DIS).
See Section 3.1.
Additionally, we used Gemini South GMOS to acquire time-series imaging
of J123950.370-204142.28 on UT 2021 June 28 as part of the program
GS-2021A-DD-108. We obtained 161 back-to-back g-band exposures over a
66 minute baseline to test for photometric variability.
See Section 3.6.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 171 60 *Measured and derived white dwarf parameters
table2.dat 59 17 Binary parameters
fig6.dat 36 305 Radial velocity measurements
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Note on table1.dat: J0130-0530, J0820+4543, and J2151+2730 were selected with
Gaia DR2 and do not belong in the Gaia eDR3-based sample, but are ELM
WD binaries included here for completeness.
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See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/ApJ/743/138 : Spectroscopic survey of bright WDs (Gianninas+, 2011)
J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)
J/ApJ/751/55 : MMT hypervelocity star survey. II. (Brown+, 2012)
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/ApJ/812/167 : The ELM survey. VI. 11 ELM WD binaries (Gianninas+, 2015)
J/MNRAS/446/4078 : New WD stars in SDSS DR10 (Kepler+, 2015)
J/A+A/595/A35 : Low-mass helium WDs evolutionary models (Istrate+, 2016)
J/MNRAS/455/3413 : New WD and subdwarf stars in SDSS DR12 (Kepler+, 2016)
J/ApJ/839/23 : Subdwarf A stars vs ELM WDs radial velocities (Brown+, 2017)
J/MNRAS/471/4218 : 4 low-mass WD candidates velocities (Kilic+, 2017)
J/MNRAS/475/2480 : Extremely-low mass WD star (Pelisoli+, 2018)
J/MNRAS/488/2892 : Gaia DR2 extremely low-mass WD candidates (Pelisoli+, 2019)
J/ApJ/892/L35 : He+He WD SDSS J232230.20+050942.0 RVels (Brown+, 2020)
J/ApJ/889/49 : The ELM Survey. VIII. Double WD binaries (Brown+, 2020)
J/A+A/641/A157 : Limb-darkening coefficients for WDs (Claret+, 2020)
J/ApJ/894/53 : ELM Survey South. I. RVs for 6 ELM WDs (Kosakowski+, 2020)
J/MNRAS/508/3877 : Catalogue of WDs in Gaia EDR3 (Gentile+, 2021)
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- 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 I1 --- Pub [0/1] Previously published object (1)
40 I1 --- Bin [0/1] Binary with an orbital solution
(1=true; 38 occurrences)
42- 47 F6.3 mag g0mag [16/19] De-reddened SDSS g band AB magnitude
49- 53 F5.3 mag e_g0mag [0.01/0.04] Uncertainty in g0mag
55- 60 F6.3 mag (g-r)0 [-0.4/-0.11] De-reddened SDSS (g-r) color
62- 66 F5.3 mag e_(g-r)0 [0.016/0.05] Uncertainty in (g-r)0
68- 72 F5.3 mag (u-g)0 [0.01/1.02] De-reddened SDSS (u-g) color
74- 78 F5.3 mag e_(u-g)0 [0.02/0.1] Uncertainty in (u-g)0
80- 84 I5 K Teff [8927/22614] Effective temperature
86- 88 I3 K e_Teff [90/920] Uncertainty in Teff
90- 94 F5.3 [cm/s2] logg [4.4/8] log surface gravity
96-100 F5.3 [cm/s2] e_logg [0.02/0.3] Uncertainty in log(g)
102-106 F5.3 Msun Mass [0.17/0.6] Stellar mass
108-112 F5.3 Msun e_Mass [0.01/0.1] Uncertainty in Mass
114-118 F5.2 mag gMAG [3.6/11.5] Absolute SDSS g band AB magnitude
120-123 F4.2 mag e_gMAG [0.05/0.5] Uncertainty in gMag
125-129 F5.3 kpc Dspec [0.19/8.3] Spectroscopic derived distance
131-135 F5.3 kpc e_Dspec [0.019/3.5] Uncertainty in Dspec
137-143 F7.4 mas plx [-0.03/3.4] Gaia EDR3 parallax
145-150 F6.4 mas e_plx [0.07/0.4] Uncertainty in plx
153-171 I19 --- Gaia Gaia EDR3 source identifier
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Note (1): Code set to 1 if previously published in Brown+ 2020, J/ApJ/892/L35
and 2020, J/ApJ/889/49 (Paper VIII); 21 occurrences
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier (JHHMM+DDMM)
12- 18 F7.5 d Per [0.015/0.93] Orbital period (1)
20- 26 F7.5 d e_Per [5e-05/0.02] Uncertainty in Per
28- 32 F5.1 km/s K [89/558] Radial velocity semi-amplitude
34- 37 F4.1 km/s e_K [3/13] Uncertainty in K
39- 44 F6.1 km/s gamma [-205/87] Systemic velocity corrected for
gravitational redshift, γ
46- 49 F4.1 km/s e_gamma [2.8/14] Uncertainty in gamma
51- 54 F4.2 Msun M2 [0.19/1.1] Minimum mass companion, M2,min
56- 59 F4.1 --- logtau [6.6/11.7] log maximum gravitational-wave
merger timescale, logτGW,max
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Note (1): J0745+2104 observations have a period alias at P=0.343 days.
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Byte-by-byte Description of file: fig6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Object identifier (JHHMM+DDMM)
12- 22 F11.6 d HJD [5741/9553] Heliocentric Julian Date; HJD-2450000
24- 30 F7.2 km/s HRV [-509/537] Heliocentric radial velocity
32- 36 F5.2 km/s e_HRV [3/93] Uncertainty in HRV
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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 Cat. J/ApJ/889/49
Brown et al. Paper IX. 2022ApJ...933...94B 2022ApJ...933...94B This catalog
(End) Prepared by [AAS], Katia van der Woerd [CDS] 01-Jul-2024