J/ApJS/246/4 Catalog of ultrawide binary stars from Gaia DR2 (Tian+, 2020)
The separation distribution of ultrawide binaries across Galactic populations.
Tian H.-J., El-Badry K., Rix H.-W., Gould A.
<Astrophys. J. Suppl. Ser., 246, 4 (2020)>
=2020ApJS..246....4T 2020ApJS..246....4T
ADC_Keywords: Stars, double and multiple; Positional data; Photometry; Optical;
Radial velocities
Keywords: Binary stars ; Visual binary stars ; Astrometric binary stars ;
Galaxy stellar content ; Galaxy stellar disks ; Galaxy stellar halos ;
Star formation ; Astrostatistics
Abstract:
We present an extensive and pure sample of ultrawide binary stars with
separations of 0.01≲s/pc≲1 in the solar neighborhood. Using data
from Gaia DR2, we define kinematic subpopulations via the systems'
tangential velocities, i.e., disk-like (v⊥,tot≤40km/s),
intermediate (v⊥,tot=40-85km/s), and halo-like
(v⊥,tot≥85km/s) binaries, presuming that these velocity cuts
represent a rough ordering in the binaries' age and metallicity.
Through stringent cuts on astrometric precision, we can obtain pure
binary samples at such wide separations with thousands of binaries in
each sample. Fitting a smoothly broken power law for the separation
distribution, we find that its slope at s=102.5-4au is the same for
all subpopulations, p(s)∝sγ with γ~-1.54.
However, the logarithmic slope of p(s) steepens at s≳104au. We find
some evidences that the degree of steepening increases with the
binaries' age, with a slope change of only Δγ∼0.5 for
disk-like stars, but Δγ≳1 for halo-like stars. This trend
is contrary to what might be expected if steepening at wide
separations were due to gravitational perturbations by molecular
clouds or stars, which would preferentially disrupt disk binaries. If
we were to interpret steepening at s≳104au as a consequence of
disruption by MAssive Compact Halo Objects (MACHOs), we would have to
invoke a MACHO population inconsistent with other constraints. As a
more plausible alternative, we propose a simple model to predict the
separation distribution of wide binaries formed in dissolving star
clusters. This model generically predicts γ~-1.5 as observed,
with steepening at larger separations due to the finite size of
binaries' birth clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 638 807611 Catalog of all candidate wide binaries (a<1pc)
selected from Gaia DR2 in the solar neighborhood
with distances d<4kpc
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Description of files:
Also available on the FTP, the file "All_candidates.fits" is the
original catalog in FITS format.
"WBs_Disklike.csv", "WBs_Intermediate.csv" and "WBs_Halolike.csv" are
the threee subsets in original CSV format for disk-like
(v⊥,tot≤40km/s), intermediate (v⊥,tot=40-85km/s), and
halo-like (v⊥,tot≥85km/s) binaries, respectively.
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/133/889 : Faint companions of Hipparcos stars (Lepine+, 2007)
J/AJ/139/2566 : SLoWPoKES catalog (Dhital+, 2010)
J/ApJ/790/158 : Candidate halo wide binaries (Allen+, 2014)
J/MNRAS/472/675 : Wide binaries in Tycho-Gaia: search method (Andrews+, 2017)
J/AJ/153/259 : The GAMBLES extension of the SLoWPoKES cat. (Oelkers+, 2017)
J/AJ/155/149 : Co-moving stars observed by Gaia (Bochanski+, 2018)
J/AJ/156/259 : Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)
J/AJ/157/78 : Multiple star systems from GaiaDR2 (Jimenez-Esteban+, 2019)
J/other/JDSO/15.434 : New Binary Systems from Data of Gaia DR2 (Romanov, 2019)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Gaia2 Gaia DR2 identifier of Star 2
(785,036 uniques) (source_id2)
21- 35 F15.11 deg RA2deg Gaia DR2 barycentric right ascension (ICRS)
at Ep=2015.5 of Star 2 (ra2)
37- 51 F15.11 deg DE2deg Gaia DR2 barycentric declination (ICRS)
at Ep=2015.5 of Star 2 (dec2)
53- 65 F13.6 --- chi2AL2 [22/135246] Star 2 astrometric goodness of
fit (χ2) in the along-scan direction
(astrometricchi2al_2)
67- 70 I4 --- NgAL2 [44/1100] Star 2 number of good CCD transits
(astrometricngoodobsal2)
72- 80 F9.3 --- RFG2 [50/12061] Star 2 G-band mean flux divided
by its error (photgmeanfluxover_error2)
82- 91 F10.3 --- RFRP2 [10/192345] Star 2 integrated RP mean flux
divided by its error
(photrpmeanfluxover_error2)
93-101 F9.3 --- RFBP2 [10/73309] Star 2 integrated BP mean flux
divided by its error
(photbpmeanfluxover_error2)
103-107 F5.3 --- E(BR/RP)2 [1/2.5] Star 2 BP/RP excess factor
(photbprpexcessfactor2)
109-117 F9.3 mas/yr pmRA2 [-2251/4106] Star 2 proper motion in right
ascension direction (pmRA*cosDE) (pmra2)
119-123 F5.3 mas/yr e_pmRA2 [0.01/4.5] pmRA2 standard error (pmra_error2)
125-133 F9.3 mas/yr pmDE2 [-3541/3156] Star 2 proper motion in
declination (pmdec2)
135-139 F5.3 mas/yr e_pmDE2 [0.01/4] pmDE2 standard error (pmdec_error2)
141-147 F7.4 mag Gmag2 [3.2/21] Star 2 G-band mean magnitude (Vega)
(photgmean_mag2)
149-155 F7.4 mag BPmag2 [3.6/24.8] Star 2 integrated BP mean
magnitude (Vega) (photbpmean_mag2)
157-163 F7.4 mag RPmag2 [2.7/21] Star 2 integrated RP mean
magnitude (Vega) (photrpmean_mag2)
165-172 F8.4 mas Plx2 [0.2/286.2] Star 2 absolute parallax
(parallax2)
174-182 F9.4 --- RPlx2 [2/5416] Parallax divided by its error
(parallaxovererror2)
184-202 I19 --- Gaia Gaia DR2 identifier of Star 1
(782,120 uniques) (source_id)
204-218 F15.11 deg RAdeg Gaia DR2 barycentric right ascension (ICRS)
at Ep=2015.5 of Star 1 (ra)
220-234 F15.11 deg DEdeg Gaia DR2 barycentric declination (ICRS)
at Ep=2015.5 of Star 1 (dec)
236-244 F9.3 mas/yr pmRA [-2241/4165] Star 1 proper motion in right
ascension direction (pmRA*cosDE) (pmra)
246-250 F5.3 mas/yr e_pmRA [0.01/1.2] pmRA1 standard error (pmra_error)
252-260 F9.3 mas/yr pmDE [-3543/3250] Star 1 proper motion in
declination (pmdec)
262-266 F5.3 mas/yr e_pmDE [0.01/1.3] pmDE1 standard error (pmdec_error)
268-274 F7.4 mag Gmag [3.2/20.1] Star 1 G-band mean magnitude
(Vega) (photgmean_mag)
276-282 F7.4 mag BPmag [3.6/21.2] Star 1 integrated BP mean
magnitude (Vega) (photbpmean_mag)
284-290 F7.4 mag RPmag [2.6/19.3] Star 1 integrated RP mean
magnitude (Vega) (photrpmean_mag)
292-299 F8.4 mas Plx [0.2/286] Star 1 absolute parallax (parallax)
301-309 F9.4 --- RPlx [20/6543] Parallax divided by its error
(parallaxovererror)
311-319 F9.2 --- chi2AL [15/189370] Star 1 astrometric goodness of
fit (χ2) in the along-scan direction
(astrometricchi2al)
321-324 I4 --- NgAL [45/1089] Star 1 number of good CCD transits
(astrometricngoodobsal)
326-334 F9.3 --- RFG [60/13735] Star 1 G-band mean flux divided
by its error (photgmeanfluxover_error)
336-345 F10.3 --- RFRP [20/842507] Star 1 integrated RP mean flux
divided by its error
(photrpmeanfluxover_error)
347-357 F11.3 --- RFBP [20/5104061] Star 1 integrated BP mean flux
divided by its error
(photbpmeanfluxover_error)
359-363 F5.3 --- E(BR/RP) [1/2.1] Star 1 BP/RP excess factor
(photbprpexcessfactor)
365-373 F9.7 deg Sepdeg [0.0003/1.1] Angular separation between
star 1 and star 2 (pairdistance)
375-384 F10.3 au Sepau [10.9/201600] Projected physical separation
between two stars (s_AU)
386 I1 --- Np [1/9] Number of pairs in neighborhood
for each binary (num)
388 I1 --- Type [1/3] Type of wide binary (binary_type) (1)
390-404 F15.11 deg GLON Star 1 galactic longitude (gl)
406-420 F15.11 deg GLAT Star 1 galactic latitude (gb)
422-436 F15.11 deg GLON2 Star 2 galactic longitude (gl2)
438-452 F15.11 deg GLAT2 Star 2 galactic latitude (gb2)
454-463 F10.5 arcsec Sep [1.2/3858] Angular separation between
the two stars (theta)
465-472 F8.6 mas/yr e_dmu [0.02/1.5] dmu uncertainty (sig_dmu)
474-484 F11.6 mas/yr dmu [0.0003/184] Total scalar difference in
proper motions between the two stars
(Δµ) (see Section 2.1)
486-496 F11.6 mas/yr dmuOrb [0.008/821] Maximum proper-motion difference
permissible for a circular orbit of total
mass 5M☉ (dmu_orbit)
498-504 F7.4 mag GMag2 [-5.2/16] Star 2 absolute G-band magnitude
(MG2)
506-512 F7.4 mag GMag [-3/16] Star 1 absolute G-band magnitude (MG)
514-520 F7.2 km/s RV2 [-325/725]? Star 2 spectroscopic barycentric
radial velocity (radial_velocity2)
522-526 F5.2 km/s e_RV2 [0.1/20]? RV2 standard error
(radialvelocityerror2)
528-534 F7.2 km/s RV [-716/565]? Star 1 spectroscopic barycentric
radial velocity (radial_velocity)
536-540 F5.2 km/s e_RV [0.1/20]? RV1 standard error
(radialvelocityerror)
542-549 F8.3 km/s UGaia [-290/547]? Star 1 radial velocity in the
Cartesian coordinates (positive to the
Galactic center) (U_gaia)
551-558 F8.3 km/s VGaia [-498/652]? Star 1 azimuthal velocity in the
Cartesian coordinates (V_gaia)
560-567 F8.3 km/s WGaia [-255/338]? Star 1 vertical velocity in the
Cartesian coordinates (W_gaia)
569-574 F6.3 km/s e_UGaia [0.03/25]? UGaia error (eU_gaia)
576-581 F6.3 km/s e_VGaia [0.03/20]? VGaia error (eV_gaia)
583-588 F6.3 km/s e_WGaia [0.02/20]? WGaia error (eW_gaia)
590-597 F8.3 km/s UGaia2 [-534/335]? Star 2 radial velocity in the
Cartesian coordinates (positive to the
Galactic center) (U_gaia2)
599-606 F8.3 km/s VGaia2 [-500/532]? Star 2 azimuthal velocity in the
Cartesian coordinates (V_gaia2)
608-615 F8.3 km/s WGaia2 [-381/175]? Star 2 vertical velocity in the
(W_gaia2)
617-622 F6.3 km/s e_UGaia2 [0.05/20]? UGaia2 error (eU_gaia2)
624-629 F6.3 km/s e_VGaia2 [0.03/20]? VGaia2 error (eV_gaia2)
631-636 F6.3 km/s e_WGaia2 [0.04/19]? WGaia2 error (eW_gaia2)
638 A1 --- Pop [dhi ] Binary kinematic subpopulation;
column added by CDS (2)
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Note (1): Type of wide binary as follows:
1 = MS-WD ("main-sequence"-white dwarf; 42,839 occurrences),
2 = WD-WD (440 occurrences),
3 = MS-MS (764,332 occurrences).
Note (2): Kinematic subpopulations define via the systems' tangential
velocities as follows:
d = disk-like (v⊥,tot≤40km/s; 4362 occurrences),
i = intermediate (v⊥,tot=40-85km/s; 10090 occurrences), and
h = halo-like (v⊥,tot≥85km/s; 4351 occurrences).
See section 3 for further explanations.
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History:
Catalog (Table 2 description in the paper) in FITS and subsets in CSV
sent by the author.
27-May-2020:Insert into VizieR
12-Nov-2020: Column "Pop" corrected
Acknowledgements:
Haijun Tian [hjtian at lamost.org]
(End) Emmanuelle Perret [CDS] 17-Apr-2020