J/AJ/168/211 Ultracool dwarf candidates from machine-learning (Brooks+, 2024)
Discovery of 118 new ultracool dwarf candidates using machine-learning
techniques.
Brooks H., Caselden D., Kirkpatrick J.D., Raghu Y., Elachi C.A.,
Grigorian J., Trek A., Washburn A., Higashimura H., Meisner A.M.,
Schneider A.C., Faherty J.K., Marocco F., Gelino C.R., Gagne J.,
Bickle T.P., Tang S.-Y., Rothermich A., Burgasser A.J., Kuchner M.J.,
Beaulieu P., Bell J., Colin G., Colombo G., Dereveanco A., Flores D.P.,
Glebov K., Gramaize L., Hamlet L., Hinckley K., Kabatnik M., Kiwy F.,
Martin D.W., Palma Mendez R.F., Pendrill B., Ruiz L., Sanchez J.,
Sainio A., Schumann J., Schonau M., Tanner C., Stevnbak N., Stenner A.,
Thevenot M., Thakur V., Voloshin N.V., Wedracki Z.,
The Backyard Worlds: Planet 9 Collaboration
<Astron. J., 168, 211 (2024)>
=2024AJ....168..211B 2024AJ....168..211B
ADC_Keywords: Models ; Photometry, classification ; Optical ; Infrared ;
Stars, brown dwarf ; Stars, dwarfs ; Stars, subdwarf;
Stars, M-type; Stars, L-type; Stars, T-type; Spectral types
Keywords: Brown dwarfs ; Subdwarf stars ; Low mass stars
Abstract:
We present the discovery of 118 new ultracool dwarf candidates,
discovered using a new machine-learning tool, named SMDET, applied to
time-series images from the Wide-field Infrared Survey Explorer. We
gathered photometric and astrometric data to estimate each candidate's
spectral type, distance, and tangential velocity. This sample has a
photometrically estimated spectral class distribution of 28 M dwarfs,
64 L dwarfs, and 18 T dwarfs. We also identify a T-subdwarf candidate,
two extreme T-subdwarf candidates, and two candidate young ultracool
dwarfs. Five objects did not have enough photometric data for any
estimations to be made. To validate our estimated spectral types,
spectra were collected for two objects, yielding confirmed spectral
types of T5 (estimated T5) and T3 (estimated T4). Demonstrating the
effectiveness of machine-learning tools as a new large-scale discovery
technique.
Description:
Archival photometric data were collected for the 118 discoveries to
help with source characterization.
The catalogs used to gather the photometry were CatWISE2020
(Marocco+ 2021, II/365), the AllWISE Source Catalog
(Cutri+ 2013, II/328), the VISTA Hemisphere Survey (VHS;
Cross+ 2012, II/382, and McMahon+ 2020, II/367), the UKIRT Infrared
Deep Sky Survey Large Area Survey Data Release 9/UKIRT Hemisphere
Survey (UKIDSS LAS DR9/UHS; Lawrence+ 2012, II/319, and
Dye+ 2018, 2018MNRAS.473.5113D 2018MNRAS.473.5113D), and PanSTARRS Data Release 2
(PanSTARRS DR2; Chambers+ 2016, II/349 and II/389). Any catalogs
associated rejection table was not used during the query for
photometric data. The associated photometric bands used in our
analysis were W1 and W2 from CatWISE2020, W3 and W4 from AllWISE,
J and Ks from VHS, J and KMKO from UKIDSS LAS DR9/UHS, and gps,
rps, ips, zps, yps from PanSTARRS DR2.
The CatWISE2020 Catalog contains positions and brightnesses for
1,890,715,640 sources selected from combined Wide-field Infrared
Survey Explore (WISE) and NEOWISE all-sky survey data collected from
2010 to 2018 at 3.4 and 4.6microns (W1 and W2). WISE was launched on
2009 December 14, with its 40cm telescope, and observed from
2010 January 7 to 2011 February 1. The surveying resumed on
2013 December 13 and the telescope was renamed NEOWISE.
The AllWISE program extends the work of the successful WISE mission by
combining data from the cryogenic (WISE) and post-cryogenic survey
(NEOWISE) phases to form a comprehensive view of the sky in the 3.4,
4.6, 12 and 22um mid-infrared bandpasses (hereafter W1, W2, W3 and W4).
The Vista Hemisphere Survey (VHS) observations were made with the
VIRCAM instrument on the ESO-VISTA telescope, located at Cerro Paranal
Observatory in Chile, between 2009-11-04T12:29:43 and
2017-04-01T14:59:29 in Y, J, H and Ks filters.
The UKIRT Infrared Deep Sky Survey (UKIDSS) uses the Wide Field Camera
(WFCAM), with a field of view of 0.21 square degrees, mounted on the
3.8m United Kingdom Infra-red Telescope (UKIRT) in Hawaii. The UKIRT
Hemisphere Survey (UHS) combines the Large Area Survey (LAS), Galactic
Plane Survey (GPS) and Galactic Clusters Survey (GCS).
The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS)
is a system for wide-field astronomical imaging developed and operated
by the Institute for Astronomy at the University of Hawaii. The PS1
survey used a 1.8m telescope and its 1.4 Gigapixel camera (GPC1) to
image the sky in five broadband filters (g, r, i, z, y). PS1 took
approximately 370000 exposures from 2010 to 2015.
We acquired spectra for two objects, CWISE J125247.68+522015.5 and
CWISE J160347.72-732054.3, to validate our spectral-type estimates.
We observed J1252+5220 on the night of 2019 January 22 (UT) using the
SpeX spectrograph on NASA's IRTF telescope.
We observed J1603-7320 on the night of 2018 April 1 (UT) using the
Cornell Infrared Imaging Spectrograph (ARCoIRIS, R∼3500) on the 4m
Blanco telescope located at the Cerro Tololo Inter-American Observatory.
See Section 4.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 714 118 Discoverer, photometry, astrometry, and derived
quantities of ultra cool dwarf candidates
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/382 : VIKING catalogue data release 4 (Cross+, 2012)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
II/367 : The VISTA Hemisphere Survey (VHS) cat. DR5 (McMahon+, 2020)
II/365 : The CatWISE2020 cat. (updat. v. 28-Jan-2021) (Marocco+, 2021)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
II/389 : The Pan-STARRS release 1 (PS1) Survey - DR2 (Magnier+, 2025)
J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/AJ/137/1 : Proper motions & astrometry: late-type dwarfs (Faherty+, 2009)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/ApJ/783/122 : AllWISE motion survey (Kirkpatrick+, 2014)
J/ApJ/781/4 : Photometry of high proper motion objects: WISE (Luhman, 2014)
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/817/112 : NEOWISE/AllWISE high proper motion objects (Schneider+, 2016)
J/A+A/589/A49 : Photometric brown-dwarf classification (Skrzypek+, 2016)
J/AJ/153/257 : Comoving stars in Gaia DR1 (Oh+, 2017)
J/ApJS/234/1 : Cat. of M, L, & T dwarfs from PS1 3π Survey (Best+, 2018)
J/ApJ/862/106 : Stellar and substellar members in Coma Berenices (Tang+, 2018)
J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)
J/A+A/642/A115 : CARMENES input catalogue of M dwarfs. V. (Cifuentes+, 2020)
J/AJ/160/279 : Untangling the Gal. II. Structure within 3kpc (Kounkel+, 2020)
J/ApJ/889/74 : Spitzer follow-up of Y brown dwarfs (Meisner+, 2020)
J/ApJ/898/77 : NIR spectra of 2 extreme T-type subdwarfs (Schneider+, 2020)
J/ApJS/253/7 : Full-sky census: brown dwarfs within 20pc (Kirkpatrick+, 2021)
J/A+A/664/A70 : Li depletion boundary in stellar assoc. (Galindo-Guil+, 2022)
J/ApJ/939/94 : New associations in Gaia DR3 solar neighborh. (Moranta+, 2022)
J/MNRAS/513/5701 : Silicate clouds in ultracool dwarfs (Suarez+, 2022)
J/AJ/166/103 : UKIRT Hemisphere Survey L, T & Y dwarfs cat (Schneider+, 2023
J/ApJ/945/119 : The Oceanus moving group members from Gaia DR3 (Gagne+, 2023)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- CWISE CWISE Designation
21- 29 F9.5 deg RAdeg [1/356] CWISE Right Ascension (J2000) (1)
31- 39 F9.5 deg DEdeg [-84/90] CWISE Declination (J2000) (1)
41- 47 F7.5 deg e_RAdeg [0.02/0.34] Uncertainty in RAdeg
49- 55 F7.5 deg e_DEdeg [0.03/0.35] Uncertainty in DEdeg
57- 68 F12.6 d MJD [56653/57792] CWISE Modified Julian Date
70- 80 F11.7 deg RAVHSdeg [21/346]? VHS Right Ascension (J2000) (1)
82- 92 F11.7 deg DEVHSdeg [-84/-4]? VHS Declination (J2000) (1)
94- 98 I5 d MJDVHS [55263/57767]? VHS Modified Julian
Date (1)
100-110 F11.7 deg RALASdeg [1/209]? UKIDSS LAS DR9 Right Ascension
in decimal degrees (J2000) (1)
112-121 F10.7 deg DELASdeg [-4/34]? UKIDSS LAS DR9 Declination in
decimal degrees (J2000) (1)
123-127 I5 d MJDLAS [53856/56053]? UKIDSS Modified Julian
Date (1)
129-137 F9.5 deg RAUHSdeg [3/356]? UHS Right Ascension (J2000) (1)
139-146 F8.5 deg DEUHSdeg [4/57]? UHS Declination (J2000) (1)
148-152 I5 d MJDUHS [56180/57676]? UHS Modified Julian
Date (1)
154-162 F9.5 deg RAPSdeg [1/346]? PanSTARRS DR2 Right Ascension in
decimal degrees (J2000) (1)
164-172 F9.5 deg DEPSdeg [-29/90]? PanSTARRS DR2 Declination in
decimal degrees (J2000) (1)
174-180 F7.5 deg e_RAPSdeg [4e-3/0.17]? Uncertainty in RAPSdeg
182-188 F7.5 deg e_DEPSdeg [4e-3/0.17]? Uncertainty in DEPSdeg
190-194 I5 d MJDPS [55760/57056]? PanSTARRS DR2 Modified
Julian Date
196-435 A240 --- Discover Object Discoverer(s)
437-442 F6.3 mag W1mag [13.9/18.4] CatWISE2020 W1-band (3.35um)
apparent magnitude
444-448 F5.3 mag e_W1mag [0.01/0.2] Uncertainty in W1mag
450-455 F6.3 mag W2mag [13.4/16.9] CatWISE2020 W2-band (4.6um)
apparent magnitude
457-461 F5.3 mag e_W2mag [0.01/0.1] Uncertainty in W2mag
463-468 F6.3 mag W3mag [11.7/13.5]? AllWISE W3-band (11.6um)
apparent magnitude
470-474 F5.3 mag e_W3mag [0.2/0.6]? Uncertainty in W3mag
476-480 F5.3 mag W4mag [8.2/9.7]? AllWISE W4-band (22.1um)
apparent magnitude
482-486 F5.3 mag e_W4mag [0.459]? Uncertainty in W4mag
488-493 F6.3 mag Jmag [16/20]? VHS/UKIDSS LAS DR9 J-band
apparent magnitude
495-499 F5.3 mag e_Jmag [7e-3/0.2]? Uncertainty in Jmag
501-506 F6.3 mag Kmkomag [14.7/18.3]? UKIDSS LAS DR9 KMKO-band
apparent magnitude
508-512 F5.3 mag e_Kmkomag [0.01/0.3]? Uncertainty in Kmkomag
514-519 F6.3 mag Ksmag [14.8/17.9]? VHS Ks-band apparent
magnitude
521-525 F5.3 mag e_Ksmag [0.01/0.2]? Uncertainty in Ksmag
527-532 F6.3 mag rmag [22.046]? PanSTARRS r-band apparent
magnitude
534-538 F5.3 mag e_rmag [0.148]? Uncertainty in rmag
540-545 F6.3 mag imag [20.4/21.9]? PanSTARRS i-band apparent
magnitude
547-551 F5.3 mag e_imag [0.02/0.2]? Uncertainty in imag
553-558 F6.3 mag zmag [18.9/21.5]? PanSTARRS z-band apparent
magnitude
560-564 F5.3 mag e_zmag [0.01/0.3]? Uncertainty in zmag
566-571 F6.3 mag ymag [18/20.7]? PanSTARRS y-band apparent
magnitude
573-577 F5.3 mag e_ymag [1e-3/0.2]? Uncertainty in ymag
579-584 F6.3 arcsec/yr pmRA [-0.9/1] CatWISE2020 proper motion
in RA
586-590 F5.3 arcsec/yr e_pmRA [7e-3/0.1] Uncertainty in pmRA
592-597 F6.3 arcsec/yr pmDE [-1/0.5] CatWISE2020 proper motion
in DE
599-603 F5.3 arcsec/yr e_pmDE [7e-3/0.1] Uncertainty in pmDE
605-609 F5.3 arcsec/yr pm [0.07/1.1] CatWISE2020 total proper motion
611-616 F6.4 arcsec/yr e_pm [0.01/0.2] Uncertainty in pm
618-623 F6.3 arcsec/yr pmRAd [-0.6/0.7]? Derived proper motion in RA;
See Section 3
625-629 F5.3 arcsec/yr e_pmRAd [9e-3/0.6]? Uncertainty in pmRAd
631-636 F6.3 arcsec/yr pmDEd [-1/0.7]? Derived proper motion in DE;
See Section 3
638-642 F5.3 arcsec/yr e_pmDEd [3e-3/0.2]? Uncertainty in pmDEd
644-648 F5.3 arcsec/yr pmd [0.2/1]? Total proper motion;
See Section 3
650-654 F5.3 arcsec/yr e_pmd [0.03/0.3]? Uncertainty in pmd
656-660 A5 --- SpTp Derived estimated photometric spectral
type; See Section 4.1 (2)
662-663 A2 --- SpTs Derived spectral type from observed
spectrum; See Section 4.2
665-671 F7.3 --- chi2 [0/370]? Derived χ2 value;
See Section 4.1
673-679 F7.3 pc Dist [15.2/906]? Derived distance;
See Section 5
681-687 F7.3 pc e_Dist [0.05/118]? Uncertainty in Dist
689-696 F8.3 km/s Vtan [20.2/1629]? Derived tangential velocity;
See Section 5
698-714 F17.13 km/s e_Vtan [1.8/461]? Uncertainty in Vtan
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Note (1): Survey acronyms as:
CWISE = CatWISE2020 (II/365), from combined Wide-field Infrared Survey
Explore (WISE) and NEOWISE satellites all-sky survey data.
VHS = VISTA Hemisphere Survey (see II/367), observations made with the
VIRCAM instrument on the ESO-VISTA telescope, located at Cerro
Paranal Observatory in Chile.
UKIDSS LAS = The UKIRT Infrared Deep Sky Survey (UKIDSS) and the Large Area
Survey (LAS), Cat. II/319; using the 3.8m United Kingdom
Infra-red Telescope (UKIRT) in Hawaii.
UHS = The UKIRT Hemisphere Survey (UHS) combines the Large Area
Survey (LAS), Galactic Plane Survey (GPS) and Galactic Clusters
Survey (GCS), using the 3.8m United Kingdom Infra-red
Telescope (UKIRT) in Hawaii.
PanSTARRS = The Panoramic Survey Telescope and Rapid Response
System (Pan-STARRS DR2, II/389); using a 1.8m telescope from
the University of Hawaii.
Note (2): Photometric spectral type occurrences as follows:
L0 = 7 occurrences
L1 = 19 occurrences
L2 = 7 occurrences
L3 = 7 occurrences
L4 = 10 occurrences
L5 = 7 occurrences
L6 = 3 occurrences
L8 = 4 occurrences
M1 = 1 occurrence
M4 = 1 occurrence
M5 = 2 occurrences
M6 = 2 occurrences
M7 = 2 occurrences
M8 = 8 occurrences
M9 = 12 occurrences
T1 = 2 occurrences
T2 = 3 occurrences
T3 = 3 occurrences
T4 = 1 occurrence
T5 = 3 occurrences
T6 = 2 occurrences
T7 = 4 occurrences
esdT? = 2 occurrences, extreme T subdwarf
sdT8? = 1 occurrence, T subdwarf
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History:
From electronic version of the journal
09-Jul-2025: Insert into VizieR
10-Jul-2025: CWISE MJD corrected
Acknowledgements:
Hunter Brooks [hcb98 at nau.edu]
(End) Prepared by [AAS], Robin Leichtnam [CDS] 25-Jun-2025