J/AJ/167/5 WISE J085510.83-071442.5 spectrum with JWST/NIRSpec (Luhman+, 2024)
JWST/NIRSpec Observations of the Coldest Known Brown Dwarf.
Luhman K.L., Tremblin P., Alves de Oliveira C., Birkmann S.M., Baraffe I.,
Chabrier G., Manjavacas E., Parker R.J., Valenti J.
<Astron. J., 167, 5 (2024)>
=2024AJ....167....5L 2024AJ....167....5L
ADC_Keywords: Stars, brown dwarf; Exoplanets; Spectra, infrared
Keywords: Brown dwarfs ; Y dwarfs ; Exoplanet atmospheres
Abstract:
We present 1-5µm spectroscopy of the coldest known brown dwarf,
WISEJ085510.83-071442.5 (WISE0855), performed with the Near-Infrared
Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST).
NIRSpec has dramatically improved the measurement of the spectral
energy distribution (SED) of WISE0855 in terms of wavelength coverage,
signal-to-noise ratios, and spectral resolution. We have performed
preliminary modeling of the NIRSpec data using the ATMO 2020 models of
cloudless atmospheres, arriving at a best- fitting model that has
Teff=285K. That temperature is ∼20K higher than the value derived by
combining our luminosity estimate with evolutionary models (i.e., the
radius in the model fit to the SED is somewhat smaller than expected
from evolutionary models). Through comparisons to the model spectra,
we detect absorption in the fundamental band of CO, which is
consistent with an earlier detection in a ground-based spectrum and
indicates the presence of vertical mixing. Although PH3 is expected in
Y-dwarfs that experience vertical mixing, it is not detected in
WISE0855. Previous ground-based M-band spectroscopy of WISE0855 has
been cited for evidence of H2O ice clouds, but we find that the
NIRSpec data in that wavelength range are matched well by our
cloudless model. Thus, clear evidence of H2O ice clouds in WISE 0855
has not been identified yet, but it may still be present in the
NIRSpec data. The physical properties of WISE0855, including the
presence of H2O clouds, can be better constrained by more detailed
fitting with both cloudless and cloudy models and the incorporation of
unpublished 5-28µm data from the Mid-infrared Instrument on JWST.
Objects:
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RA (2000) DE Designation(s)
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08 55 10.83 -07 14 42.5 WISE 0855 = WISE J085510.83-071442.5
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig3.dat 34 953 NIRSpec PRISM spectrum of WISE J085510.83-071442.5
fig4.dat 34 1488 NIRSpec G395M spectrum of WISE J085510.83-071442.5
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See also:
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)
J/ApJ/783/122 : AllWISE motion survey (Kirkpatrick+, 2014)
J/ApJ/781/4 : Photometry high proper motion objects from WISE (Luhman, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJ/832/58 : Spitzer/IRAC monitoring WISEJ085510.83-071442.5 (Esplin+, 2016)
J/ApJ/842/118 : Brown dwarfs with spectral type later than T6 (Leggett+, 2017)
J/ApJS/240/19 : Parallaxes of late-T and Y dwarfs (Kirkpatrick+, 2019)
J/ApJ/889/74 : Spitzer follow-up of Y brown dwarfs (Meisner+, 2020)
J/ApJ/899/123 : Spitzer follow up of 95 brown dwarfs (Meisner+, 2020)
J/AJ/160/63 : IR spectra 5 brown dwarfs with Gemini North IRS (Miles+, 2020)
J/ApJS/253/7 : Full-sky census brown dwarfs within 20pc (Kirkpatrick+, 2021)
J/AJ/161/177 : Spitzer IRAC photometry 36 JWSTcalibration stars (Krick+, 2021)
J/ApJ/918/11 : Infrared photometry of late-type brown dwarfs (Leggett+, 2021)
J/AJ/165/99 : Absolute Calibration III Sirius & Sun IR spectra (Rieke+, 2023)
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Byte-by-byte Description of file: fig[34].dat
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Bytes Format Units Label Explanations
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1- 9 F9.7 um Wave Wavelength
11- 22 E12.5 Jy Flux ? Flux density
24- 34 E11.5 Jy e_Flux ? Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 19-Apr-2024