J/ApJ/920/20 HST/WFC3 spectroscopy of WISEP J182831.08+265037.8 (Cushing+, 2021)
An Improved Near-infrared Spectrum of the Archetype Y Dwarf
WISEP J182831.08+265037.8.
Cushing M.C., Schneider A.C., Kirkpatrick J.D., Morley C.V., Marley M.S.,
Gelino C.R., Mace G.N., Wright E.L., Eisenhardt P.R., Skrutskie M.F.,
Marsh K.A.
<Astrophys. J., 920, 20 (2021)>
=2021ApJ...920...20C 2021ApJ...920...20C
ADC_Keywords: Stars, brown dwarf; Spectra, infrared
Keywords: Near infrared astronomy ; Y dwarfs ; Spectroscopy ; Brown
dwarfs
Abstract:
We present a Hubble Space Telescope/Wide-Field Camera 3 near-infrared
spectrum of the archetype Y-dwarf WISEPJ182831.08+265037.8. The
spectrum covers the 0.9-1.7µm wavelength range at a resolving power
of λ/Δλ∼180 and is a significant improvement over
the previously published spectrum because it covers a broader
wavelength range and is uncontaminated by light from a background
star. The spectrum is unique for a cool brown dwarf in that the flux
peaks in the Y, J, and H bands are of near equal intensity in units of
fλ. We fail to detect any absorption bands of NH3 in the
spectrum, in contrast to the predictions of chemical equilibrium
models, but tentatively identify CH4 as the carrier of an unknown
absorption feature centered at 1.015µm. Using previously published
ground- and spaced-based photometry, and using a Rayleigh-Jeans tail
to account for flux emerging longward of 4.5µm, we compute a
bolometric luminosity of log(Lbol/L☉N)=-6.50±0.02, which
is significantly lower than previously published results. Finally, we
compare the spectrum and photometry to two sets of atmospheric models
and find that the best overall match to the observed properties of
WISE1828+2650 is a ∼1Gyr old binary composed of two Teff∼325K, ∼5MJup
brown dwarfs with subsolar [C/O] ratios.
Description:
WISE 1828+2650 was observed with the Wild Field Camera 3 (WFC3) on
board Hubble Space Telecope (HST) as a part of a Cycle 20 program to
obtain grism spectroscopy of late-type T and Y dwarf candidates
(GO-12970, PI=Cushing). The WFC3 uses a 1024x1024HgCdTe detector with
a plate scale of 0.13"/pixel, which results in a field of view of
123x126". WISE-1828+2650 was observed with the G102 grism, which
covers the 0.8-1.15µm wavelength range at a resolving power of
R∼210, and the G141 grism, which covers the 1.075-1.70µm wavelength
range at a resolving power of R∼130. Direct images through the F105W
or F125W filter were also obtained before the G102 and G141 grism
images, respectively.
Objects:
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RA (2000) DE Designation(s)
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18 28 31.08 +26 50 37.7 WISEP J182831.08+265037.8 = EQ J1828+2650
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 27 212 New G102+G141 HST/WFC3 spectrum of WISE 1828+2650
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/365 : The CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)
VI/133 : A variationally computed hot NH3 line list - BYTe (Yurchenko+, 2011)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
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/MNRAS/440/1649 : ExoMol line lists for CH4 (Yurchenko+, 2014)
J/ApJ/810/158 : M,L,T dwarfs fundamental parameters & SEDs (Filippazzo+, 2015)
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/AJ/160/63 : IR spectra of 5 brown dwarfs Gemini North IRS (Miles+, 2020)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.4 um Wave [0.9/1.7] Wavelength
8- 17 E10.3 W/m2/um Flux [-3e-19/6e-19] Flux
19- 27 E9.3 W/m2/um e_Flux [8e-21/2e-19] Uncertainty in flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 06-Feb-2023