J/AJ/167/168 NIRSpec spectra of TWA 28, TWA 27A and TWA 27B (Manjavacas+, 2024)
Medium-resolution 0.97-5.3um Spectra of Very Young Benchmark Brown Dwarfs with
NIRSpec on Board the James Webb Space Telescope
Manjavacas E., Tremblin P., Birkmann S., Valenti J., Alves de Oliveira C.,
Beck T.L., Giardino G., Lutzgendorf N., Rauscher B.J., Sirianni M.
<Astron. J., 167, 168 (2024)>
=2024AJ....167..168M 2024AJ....167..168M
ADC_Keywords: Stars, L-type; Stars, M-type; Spectra, infrared
Keywords: L dwarfs ; M dwarf stars ; Spectroscopy
Abstract:
Spectra of young benchmark brown dwarfs with well-known ages are vital
to characterize other brown dwarfs, for which ages are in general not
known. These spectra are also crucial to test atmospheric models,
which have the potential to provide detailed information about the
atmospheres of these objects. However, to test atmospheric models
optimally, medium-resolution, long-wavelength-coverage spectra with
well-understood uncertainties are ideal, such as the spectra provided
by the NIRSpec instrument on board the James Webb Space Telescope. In
this paper, we present medium-resolution JWST/NIRSpec spectra of two
young brown dwarfs, TWA 28 (M9.0) and TWA 27A (M9.0), and one
planetary-mass object, TWA 27B (L6.0), members of the TW Hydrae
Association (age ∼10Myr). We show the richness of the atomic lines and
molecular bands present in the spectra. All objects show signs of a
circumstellar disk, via a near-infrared excess and/or via emission
lines. We matched a set of cloudless atmospheric spectra (ATMO), and
cloudy atmospheric spectra (BT-Settl) to our NIRSpec spectra, and
analyzed which wavelength ranges and spectral features both models
reproduce best. Both models derive consistent parameters for the three
sources, and predict the existence of CH4 at 3.35µm in TWA 27B.
Nonetheless, in contrast to other slightly older objects with similar
spectral type, like PSO 318.5-22 and VHS 1256b, this feature is not
present in the spectrum of TWA 27B. The lack of the CH4 feature might
suggest that the L-T transition of very young dwarfs starts at later
spectral types than for older brown dwarfs.
Description:
These observations were acquired 2023 February 7 using the NIRSpec IFU
on the James Webb Space Telescope as part of the Guaranteed Time
Observation program 1270 (PI: S. Birkmann).
The data were obtained using the medium-resolution gratings with a
resolution of R∼2700 at ∼2.20um, and a total wavelength coverage of
0.97-5.3um.
Objects:
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RA (2000) DE Designation(s)
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11 02 09.83 -34 30 35.5 TWA28 = 2MASS J11020983-3430355
12 07 33.46 -39 32 54.0 TWA27a = ** CVN 12A
12 07 33.49 -39 32 54.3 TWA27b = HIDDEN NAME 2M1207Ab
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1_1.dat 62 3947 TWA 27A reduced spectrum using G140H/F100LP
fig1_2.dat 62 3843 TWA 27A reduced spectrum using G235H/F170LP
fig1_3.dat 62 3639 TWA 27A reduced spectrum using G395H/F290LP
fig1_4.dat 62 3947 TWA 27B reduced spectrum using G140H/F100LP
fig1_5.dat 62 3843 TWA 27B reduced spectrum using G235H/F170LP
fig1_6.dat 62 3639 TWA 27B reduced spectrum using G395H/F290LP
fig1_7.dat 62 3947 TWA 28 reduced spectrum using G140H/F100LP
fig1_8.dat 62 3843 TWA 28 reduced spectrum using G235H/F170LP
fig1_9.dat 62 3639 TWA 28 reduced spectrum using G395H/F290LP
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See also:
J/A+A/562/A127 : NIR integral field spectra of 15 M-L dwarfs (Bonnefoy+, 2014)
J/A+A/564/A55 : 1.1-2.4um spectra of 7 young M & L dwarfs (Manjavacas+, 2014)
J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)
J/ApJ/831/125 : ALMA 887um obs. of ChaI star-forming region (Pascucci+, 2016)
J/ApJ/818/176 : HST/WFC3 NIR photometry of 2M1207b (Zhou+, 2016)
J/A+A/602/A33 : X-Shooter spectroscopy of YSOs in Lupus (Frasca+, 2017)
J/ApJ/838/73 : Brown dwarf surface gravities Keck/NIRSPEC (Martin , 2017)
J/AJ/157/101 : Cloud Atlas: HST/WFC3 NIR spectral library (Manjavacas+, 2019)
J/A+A/632/A46 : TW Hydrae association with X-shooter (Venuti+, 2019)
J/AJ/165/269 : TW Hya association candidate members (Luhman, 2023)
Byte-by-byte Description of file: fig1_[123456789].dat
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Bytes Format Units Label Explanations
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1- 20 E20.15 um Wave Wavelength observed
22- 41 E20.15 Jy Flux ? Flux
43- 62 E20.15 Jy e_Flux ? Error on Flux
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 04-Jun-2024