J/MNRAS/542/L126 Spectra of brown dwarf candidates in the ONC (Luhman, 2025)
JWST spectra of brown dwarf candidates in the Orion Nebula Cluster.
Luhman K.L.
<Mon. Not. R. Astron. Soc. 542, L126-L131 (2025)>
=2025MNRAS.542L.126L 2025MNRAS.542L.126L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, brown dwarf ; Spectra, infrared ; Spectral types
Keywords: brown dwarfs - stars: formation
Abstract:
I present an analysis of archival spectra of 200 sources toward the
Orion Nebula Cluster (ONC) that were obtained with the Near-Infrared
Spectrograph (NIRSpec) onboard the James Webb Space Telescope (JWST).
I have used these data to assess cluster membership and measure
spectral types for the targets. Fifty-three sources are classified as
likely cluster members, 24 of which have spectral types that are
suggestive of brown dwarfs (>M6). Seven of the NIRSpec targets were
previously identified as "Jupiter-mass binary objects" (JuMBOs), all
of which are background sources rather than brown dwarfs based on the
NIRSpec data. The spectral classifications of those objects are
consistent with the results of my recent study of the JWST photometry
in the ONC, which found that only a few JuMBO components have the
colours expected for brown dwarfs, none of which form pairs that have
uniquely wide separations or low masses relative to known binary brown
dwarfs.
Description:
Spectral and membership classifications of NIRSpec targets in the ONC.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 145 200 Spectral and membership classifications
sp/* . 200 Individual spectra
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See also:
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
J/AJ/146/85 : Spectral types of 1576 optical stars in ONC
(Hillenbrand+, 2013)
J/ApJ/975/162 : Spectra of brown dwarf candidates in ONC from JWST
(Luhman+, 2024)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [3/3249] Source number in MPT/APT catalog
6- 35 A30 --- Name Other source name
37- 45 F9.6 deg RAdeg Right ascension (ICRS) (1)
47- 55 F9.6 deg DEdeg Declination (ICRS) (1)
57- 82 A26 --- SpType Spectral type
84- 90 A7 --- r_SpType Spectral type reference (2)
92- 95 F4.2 mag AK ? K band extinction from NIRSpec
97-100 A4 --- Member [yes no?] ONC member?
102-145 A44 --- Evidence Evidence of membership (3)
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Note (1): Coordinates are from the reduced images in Luhman
(2024AJ....168..230L 2024AJ....168..230L).
Note (2): References as follows:
1 = this work
2 = Weights et al. (2009MNRAS.392..817W 2009MNRAS.392..817W)
3 = Hillenbrand et al. (2013AJ....146...85H 2013AJ....146...85H, cat. J/AJ/146/85)
4 = Lucas et al. (2006MNRAS.373L..60L 2006MNRAS.373L..60L)
5 = Riddick et al. (2007MNRAS.381.1077R 2007MNRAS.381.1077R)
6 = Hillenbrand (1997AJ....113.1733H 1997AJ....113.1733H, Cat. J/AJ/113/1733)
7 = Ingraham et al. (2014ApJ...782....8I 2014ApJ...782....8I, Cat. J/ApJ/782/8)
8 = Slesnick et al. (2004ApJ...610.1045S 2004ApJ...610.1045S)
9 = Luhman et al. (2025ApJ...986L..14L 2025ApJ...986L..14L)
Note (3): All sources classified as nonmembers lack late-type spectral features
and evidence of membership. Some are also resolved galaxies in the NIRCam
images.
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 F6.4 um lambda Wavelength
8- 17 F10.4 --- Flambda Flux in arbitrary units
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Acknowledgements:
Kevin Luhman, kll207(at)psu.edu
(End) Patricia Vannier [CDS] 05-Aug-2025