J/A+A/695/A195 New ultracool dwarf candidates from unTimely (Karpov+, 2025)
New ultracool dwarf candidates from multi-epoch WISE data.
Karpov S., Malkov O., Avdeeva A.
<Astron. Astrophys. 695, A195 (2025)>
=2025A&A...695A.195K 2025A&A...695A.195K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, brown dwarf ; Spectral types ; Proper motions;
Stars, distances
Keywords: surveys - proper motions - brown dwarfs
Abstract:
Thirty years after the discovery of brown dwarfs, the search for these
objects continues, particularly in the vicinity of the Sun. Objects
near the Sun are characterized by large proper motions, making them
seen as fast-moving objects. While the Gaia DR3 catalogue is a
comprehensive source of proper motions, it lacks the depth needed for
discovering fainter objects. Modern multi-epoch surveys, with their
greater depth, offer a new opportunity for systematic search for
ultracool dwarfs.
The study aims to systematically search for high proper motion objects
using the newly released catalogue of epochal WISE data in order to
identify new brown dwarf candidates in the solar neighborhood,
estimate their spectral types, distances and spatial velocities.
We used recently released unTimely catalogue of epochal detections in
unWISE coadds to search for objects with high proper motions using
simple motion detection algorithm, combined with machine learning
based artefact rejection routine. This method was used to identify
objects with proper motions exceeding approximately 0.3 arcseconds per
year. The identified objects were then cross-referenced with data from
other large-scale sky surveys to further analyze their
characteristics.
The search yielded 21885 moving objects with significant proper
motions, 258 of which had not been previously published. All except 6
of them are compatible with being ultracool dwarfs. Among these, at
least 33 were identified as most promising new T dwarf candidates,
with estimated distances closer than about 40 parsecs, and effective
temperatures less than 1300K.
Description:
The catalogue contains high proper motion objects detected in unTimely
catalogue of WISE epochal photometry that lack Simbad or Gaia DR3
counterparts and have not been published previously. Their
multi-wavelength photometry is recovered from positional cross-match
with other large-scale optical and infrared catalogues, and used to
estimate their effective temperatures via SED fitting with BT-Settl
atmosphere model grid.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 1854 258 New high-proper-motion objects detected in
this work
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
II/365 : The CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Candid Candidate ID from unTimely
24- 42 A19 --- CWISE Candidate ID from CatWISE2020,
JHHMMSS.ss+DDMMSS.s
44- 63 F20.16 deg RAdeg Right ascension (ICRS) at Ep=J2016.0
65- 85 F21.17 deg DEdeg Declination (ICRS) at Ep=J2016.0
87- 109 F23.20 arcsec/yr pmRA Proper motion in Right ascension
111- 131 F21.19 arcsec/yr e_pmRA Error of pmRA
133- 153 F21.18 arcsec/yr pmDE Proper motion in Declination
155- 175 F21.19 arcsec/yr e_pmDE Error of pmDE
177- 195 F19.17 arcsec/yr PM Proper motion
197- 217 F21.19 arcsec/yr e_PM Error of PM
219- 236 F18.15 mag W1 WISE W1 band magnitude
238- 257 F20.18 mag e_W1 Error of W1
259- 276 F18.15 mag W2 WISE W2 band magnitude
278- 297 F20.18 mag e_W2 Error of W2
299- 317 F19.15 mag uSMSS ? SkyMapper DR4 u band magnitude
319- 339 F21.18 mag e_uSMSS ? Error of uSMSS
341- 359 F19.15 mag gDELVE ? DELVE DR2 g band magnitude
361- 381 F21.18 mag e_gDELVE ? Error of gDELVE
383- 401 F19.15 mag gNSC ? NSC DR2 g band magnitude
403- 423 F21.18 mag e_gNSC ? Error of gNSC
425- 443 F19.15 mag gPS1 ? PanSTARRS DR2 g band magnitude
445- 464 F20.17 mag e_gPS1 ? Error of gPS1
466- 484 F19.15 mag gSDSS ? SDSS DR16 g band magnitude
486- 491 F6.3 mag e_gSDSS ? Error of gSDSS
493- 511 F19.15 mag gSMSS ? SkyMapper DR4 g band magnitude
513- 533 F21.18 mag e_gSMSS ? Error of gSMSS
535- 553 F19.15 mag rDELVE ? DELVE DR2 r band magnitude
555- 574 F20.17 mag e_rDELVE ? Error of rDELVE
576- 594 F19.15 mag rNSC ? NSC DR2 r band magnitude
596- 617 F22.19 mag e_rNSC ? Error of rNSC
619- 637 F19.15 mag rPS1 ? PanSTARRS DR2 r band magnitude
639- 658 F20.17 mag e_rPS1 ? Error of rPS1
660- 678 F19.15 mag rSMSS ? SkyMapper DR4 r band magnitude
680- 700 F21.18 mag e_rSMSS ? Error of rSMSS
702- 720 F19.15 mag iDELVE ? DELVE DR2 i band magnitude
722- 742 F21.18 mag e_iDELVE ? Error of iDELVE
744- 762 F19.15 mag iNSC ? NSC DR2 i band magnitude
764- 785 F22.19 mag e_iNSC ? Error of iNSC
787- 805 F19.15 mag iPS1 ? PanSTARRS DR2 i band magnitude
807- 828 F22.19 mag e_iPS1 ? Error of iPS1
830- 848 F19.15 mag iSDSS ? SDSS DR16 i band magnitude
850- 869 F20.17 mag e_iSDSS ? Error of iSDSS
871- 889 F19.15 mag iSMSS ? SkyMapper DR4 i band magnitude
891- 911 F21.18 mag e_iSMSS ? Error of iSMSS
913- 931 F19.15 mag zDELVE ? DELVE DR2 z band magnitude
933- 954 F22.19 mag e_zDELVE ? Error of zDELVE
956- 974 F19.15 mag zNSC ? NSC DR2 z band magnitude
976- 996 F21.18 mag e_zNSC ? Error of zNSC
998-1016 F19.15 mag zPS1 ? PanSTARRS DR2 z band magnitude
1018-1038 F21.18 mag e_zPS1 ? Error of zPS1
1040-1058 F19.15 mag zSDSS ? SDSS DR16 z band magnitude
1060-1080 F21.18 mag e_zSDSS ? Error of zSDSS
1082-1100 F19.15 mag zSMSS ? SkyMapper DR4 z band magnitude
1102-1122 F21.18 mag e_zSMSS ? Error of zSMSS
1124-1142 F19.15 mag yPS1 ? PanSTARRS DR2 y band magnitude
1144-1164 F21.18 mag e_yPS1 ? Error of yPS1
1166-1184 F19.15 mag YNSC ? NSC DR2 Y band magnitude
1186-1206 F21.18 mag e_YNSC ? Error of YNSC
1208-1226 F19.15 mag YVHS ? VHS DR5 Y band magnitude
1228-1235 F8.5 mag e_YVHS ? Error of YVHS
1237-1255 F19.15 mag IDENIS ? DENIS I band magnitude
1257-1276 F20.17 mag e_IDENIS ? Error of IDENIS
1278-1296 F19.15 mag J2MASS ? 2MASS J band magnitude
1298-1318 F21.18 mag e_J2MASS ? Error of J2MASS
1320-1338 F19.15 mag JDENIS ? DENIS J band magnitude
1340-1359 F20.17 mag e_JDENIS ? Error of JDENIS
1361-1379 F19.15 mag JUHS ? UHS DR2 J band magnitude
1381-1402 F22.19 mag e_JUHS ? Error of JUHS
1404-1422 F19.15 mag JVHS ? VHS DR5 J band magnitude
1424-1444 F21.18 mag e_JVHS ? Error of JVHS
1446-1464 F19.15 mag H2MASS ? 2MASS H band magnitude
1466-1486 F21.18 mag e_H2MASS ? Error of H2MASS
1488-1506 F19.15 mag HVHS ? VHS DR5 H band magnitude
1508-1515 F8.5 mag e_HVHS ? Error of HVHS
1517-1535 F19.15 mag K2MASS ? 2MASS K band magnitude
1537-1556 F20.17 mag e_K2MASS ? Error of K2MASS
1558-1576 F19.15 mag KDENIS ? DENIS K band magnitude
1578-1596 F19.16 mag e_KDENIS ? Error of KDENIS
1598-1616 F19.15 mag KUHS ? UHS DR2 K band magnitude
1618-1639 F22.19 mag e_KUHS ? Error of KUHS
1641-1659 F19.15 mag KsVHS ? VHS DR5 Ks band magnitude
1661-1681 F21.18 mag e_KsVHS ? Error of KsVHS
1683-1693 F11.5 K Teff ? Effective temperature
1695-1705 F11.6 K e_Teff ? Error of Teff
1707-1714 A8 --- SpType Estimated spectral type
1716-1736 F21.17 --- b_SpType Lower bound on spectral type
1738-1758 F21.17 --- B_SpType Upper bound on spectral type
1760 I1 --- SpMet [0/2] Method used to derive
spectral type
1762-1771 A10 --- SpMetStr Method used to derive spectral type
1773-1791 F19.15 pc Dist Estimated distance
1793-1812 F20.16 pc e_Dist Error of dist
1814-1833 F20.15 km/s Vtan Estimated tangential velocity
1835-1854 F20.16 km/s e_Vtan Error of vtan
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Acknowledgements:
Sergey Karpov, karpov.sv(at)gmail.com
References:
Meisner et al., 2023AJ....165...36M 2023AJ....165...36M, The unTimely catalogue
(End) Sergey Karpov [FZU, Czech Republic], Patricia Vannier [CDS] 04-Mar-2025