J/ApJ/889/176 Very low-mass binaries with Gaia DR2 data (Faherty+, 2020)
WISE 2150-7520AB: a very low-mass, wide comoving brown dwarf system discovered
through the Citizen Science Project Backyard Worlds: Planet 9.
Faherty J.K., Goodman S., Caselden D., Colin G., Kuchner M.J., Meisner A.M.,
Gagne J., Schneider A.C., Gonzales E.C., Bardalez Gagliuffi D.C.,
Logsdon S.E., Allers K., Burgasser A.J.
<Astrophys. J., 889, 176 (2020)>
=2020ApJ...889..176F 2020ApJ...889..176F
ADC_Keywords: Stars, brown dwarf; Stars, double and multiple; Spectral types;
Stars, masses; Proper motions
Keywords: Brown dwarfs ; L dwarfs ; Substellar companion stars ; Astrometry ;
Star formation ; T dwarfs ; Late-type dwarf stars ; Stellar kinematics
Abstract:
We report the discovery of WISE 2150-7520AB (W2150AB): a widely
separated (∼341au) very low-mass L1+T8 co-moving system. The system
consists of the previously known L1 primary 2MASS J21501592-7520367
and a newly discovered T8 secondary found at position
21:50:18.99-75:20:54.6 (MJD=57947) using Wide-field Infrared Survey
Explorer data via the Backyard Worlds: Planet 9 citizen science
project. We present Spitzer ch1 and ch2 photometry
(ch1-ch2=1.41±0.04mag) of the secondary and Folded-port InfraRed
Echellette prism spectra of both components. The sources show no
peculiar spectral or photometric signatures, indicating that each
component is likely field age. Using all observed data and the Gaia
DR2 parallax of 41.3593±0.2799mas for W2150A we deduce fundamental
parameters of log(Lbol/L☉)=-3.69±0.01, Teff=2118±62K, and
an estimated mass=72±12MJup for the L1 and
log(Lbol/L☉)=-5.64±0.02, Teff=719±61K, and an estimated
mass=34±22MJup for the T8. At a physical separation of ∼341au this
system has Ebin=1041erg, making it the lowest binding energy
system of any pair with Mtot<0.1M☉ not associated with a young
cluster. It is equivalent in estimated mass ratio, Ebin, and
physical separation to the ∼2Myr M7.25+M8.25 binary brown dwarf
2MASS J11011926-7732383AB (2M1101AB) found in the Chameleon
star-forming region. W2150AB is the widest companion system yet
observed in the field where the primary is an L dwarf or later.
Description:
We attempted to compile an up-to-date sample of very low-mass
binaries/companions, drawing from both large survey papers such as
Deacon+ (2014ApJ...792..119D 2014ApJ...792..119D), spectral binary papers such as
Bardalez Gagliuffi+ (2014ApJ...794..143B 2014ApJ...794..143B), and individual young
companion papers such as Artigau+ (2015ApJ...806..254A 2015ApJ...806..254A), and
Naud+ (2014ApJ...787....5N 2014ApJ...787....5N). We list the objects displayed in
Figures 7 and 8 with Mtot<0.2MSun organized by increasing binding
energy in Table 2. Additionally we searched the Gaia DR2 catalog to
see if either the primary or secondary component had astrometry and/or
photometry reported and we list the results in Table 3. See Section 9.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 109 179 Companion systems with total mass <0.2MSun
(System properties)
table3.dat 171 179 Companion systems with total mass <0.2MSun
(Dynamics)
refs.dat 70 98 References
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
J/AJ/126/1526 : IR photometry of ultracool dwarfs (Bouy+, 2003)
J/AJ/125/3302 : HST binary very low mass stars & brown dwarfs (Gizis+, 2003)
J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004)
J/A+A/435/363 : Southern Infrared Proper Motion Survey (Deacon+, 2005)
J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)
J/ApJ/667/520 : Proper motions in multiple systems (Caballero, 2007)
J/MNRAS/390/1517 : Proper motions of field L and T dwarfs (Casewell+, 2008)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/ApJ/710/1142 : SpeX spectros. of low mass binaries. I. (Burgasser+, 2010)
J/ApJS/190/100 : NIR proper motion survey using 2MASS (Kirkpatrick+, 2010)
J/ApJ/710/1627 : Mid-IR photometry of cold brown dwarfs (Leggett+, 2010)
J/MNRAS/404/1817 : 2MASS/SDSS data for 806 ultracool dwarfs (Zhang+, 2010)
J/A+A/529/A102 : MOA-2007-BLG-387Lb light curve I band (Batista+, 2011)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/ApJ/752/56 : BDKP. III. Parallaxes for ultracool dwarfs (Faherty+, 2012)
J/MNRAS/433/457 : 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)
J/MNRAS/430/1171 : Sub-stellar birth rate from UKIDSS (Day-Jones+, 2013)
J/A+A/556/A133 : Astrometric orbit of DENIS J082303.1-49120 (Sahlmann+, 2013)
J/ApJ/794/143 : New SpeX Observations of M7-L6 Dwarfs (Bardalez+, 2014)
J/ApJ/792/119 : Companions to nearby stars from Pan-STARRS 1 (Deacon+, 2014)
J/ApJ/783/122 : AllWISE motion survey (Kirkpatrick+, 2014)
J/ApJ/810/158 : M,L,T dwarfs parameters and SEDs (Filippazzo+, 2015)
J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015)
J/MNRAS/449/3651 : L and T dwarfs from UKIDSS LAS (Marocco+, 2015)
J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)
J/ApJS/224/36 : The AllWISE motion survey (AllWISE2) (Kirkpatrick+, 2016)
J/ApJ/833/96 : Hawaii infrared plx prog. II. Ultracool dwarfs (Liu+, 2016)
J/ApJS/231/15 : Astrometric monitoring of dwarf binaries (Dupuy+, 2017)
J/ApJ/842/118 : BDs with spectral type later than T6 (Leggett+, 2017)
J/ApJ/856/23 : BANYAN. XI. The BANYAN Σ algorithm (Gagne+, 2018)
J/ApJS/240/19 : Parallaxes of late-T and Y dwarfs (Kirkpatrick+, 2019)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID System Name (1)
19- 20 I2 h RAh Hour of Right Ascension (J2000) (2)
22- 23 I2 min RAm Minute of Right Ascension (J2000) (2)
25- 29 F5.2 s RAs Second of Right Ascension (J2000) (2)
31 A1 --- DE- Sign of the Declination (J2000)(2)
32- 33 I2 deg DEd Degree of Declination (J2000) (2)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000) (2)
38- 41 F4.1 arcsec DEs Arcsecond of Declination (J2000) (2)
43- 47 A5 --- SpT1 Spectral Type, Method 1
49- 53 A5 --- SpT2 Spectral Type, Method 2
55- 60 F6.4 Msun Mass1 [0.017/0.19] Companion mass, Method 1 (3)
62- 67 F6.4 Msun Mass2 [0.003/0.12] Companion mass, Method 2 (3)
69- 74 F6.4 Msun Mtot [0.028/0.25] Total mass
76- 79 F4.2 --- q [0.01/1.63] Mass Ratio
81- 87 F7.2 au Sep [0.03/6700] Separation
89- 96 F8.2 10+34J Ebin [0.17/22012] Binding energy
in 1041erg units (4)
98-104 A7 --- Yng? Young source? (5)
106-107 I2 --- Ref Reference (see refs.dat)
109 A1 --- Flag Flag on sources of dynamical/total masses (6)
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Note (1): The name used is a shorthand from the discovery paper or from the
coordinates of the primary.
Note (2): The positions are of the primary in the system.
For "0518-2828", coordinates "05 18 99.50 -28 28 37.2" are updated for
"05 18 59.95 -28 28 37.2" by CDS.
Note (3): Masses were either obtained from dynamical mass measurements (and
noted as such), discovery paper estimates or by applying the spectral
type to mass relation from Dupuy & Liu (2017, J/ApJS/231/15).
Note (4): To account for a distribution of the eccentricities of the
binary orbits, we multiply the physical separation by 1.26 and use this
value to compute the binding energy.
Note (5): Note as follows:
Yng = source associated with a cluster/moving-group/star-forming-region
with an age <1Gyr.
Not Yng = no associated region therefore a field age for the source.
Note (6): Flags on the sources of dynamical/total masses as follows:
a = Dynamical masses from Dupuy & Liu (2017, J/ApJS/231/15);
b = Total masses listed in Dupuy & Liu (2017, J/ApJS/231/15) but individual
masses were not therefore we used the relation in that work to estimate
object masses;
c = Dynamical masses from Garcia et al. (2017ApJ...846...97G 2017ApJ...846...97G);
d = Dynamical masses from Dieterich et al. (2018ApJ...865...28D 2018ApJ...865...28D).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID System Name
19- 20 I2 h RAh ? Hour of Right Ascension, Primary (J2000)
22- 23 I2 min RAm ? Minute of Right Ascension, Primary (J2000)
25- 29 F5.2 s RAs ? Second of Right Ascension, Primary (J2000)
31 A1 --- DE- Sign of the Declination, Primary (J2000)
32- 33 I2 deg DEd ? Degree of Declination, Primary (J2000)
35- 36 I2 arcmin DEm ? Arcminute of Declination, Primary (J2000)
38- 41 F4.1 arcsec DEs ? Arcsecond of Declination, Primary (J2000)
43- 50 F8.4 mas Plx1 [5.4/250]? Gaia DR2 primary parallax
52- 57 F6.4 mas e_Plx1 [0.04/4]? Uncertainty in Plx1
59- 66 F8.3 mas/yr pmRA1 [-778/2585]? Gaia DR2 proper motion in RA,
Primary
68- 72 F5.3 mas/yr e_pmRA1 [0.07/3.5]? Uncertainty in pmRA1
74- 82 F9.3 mas/yr pmDE1 [-1506/825]? Gaia DR2 proper motion in DEC,
Primary
84- 88 F5.3 mas/yr e_pmDE1 [0.05/2.7]? Uncertainty in pmDE1
90- 94 F5.2 mag Gmag1 [5.7/21.2]? Gaia DR2 G band magnitude, Primary
96- 97 I2 h RA2h ? Hour of Right Ascension, Secondary (J2000)
99-100 I2 min RA2m ? Minute of Right Ascension, Secondary (J2000)
102-106 F5.2 s RA2s ? Second of Right Ascension, Secondary (J2000)
108 A1 --- DE2- Sign of the Declination, Secondary (J2000)
109-110 I2 deg DE2d ? Degree of Declination, Secondary (J2000)
112-113 I2 arcmin DE2m ? Arcminute of Declination, Secondary (J2000)
115-119 F5.2 arcsec DE2s ? Arcsecond of Declination, Secondary (J2000)
121-127 F7.4 mas Plx2 [5.4/82.1]? Gaia DR2 secondary parallax
129-134 F6.4 mas e_Plx2 [0.14/1.6]? Uncertainty in Plx2
136-143 F8.3 mas/yr pmRA2 [-644/672]? Gaia DR2 proper motion in RA,
Secondary
145-149 F5.3 mas/yr e_pmRA2 [0.2/4.1]? Uncertainty in pmRA2
151-159 F9.3 mas/yr pmDE2 [-1499/80]? Gaia DR2 proper motion in DEC,
Secondary
161-165 F5.3 mas/yr e_pmDE2 [0.17/3.3]? Uncertainty in pmDE2
167-171 F5.2 mag Gmag2 [16.4/21]? Gaia DR2 G band magnitude, Secondary
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode Bibcode of the reference
24- 48 A25 --- Auth First author's name
50- 70 A21 --- Comm Comment
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jul-2021