J/AJ/160/63 IR spectra of 5 brown dwarfs with Gemini North IRS (Miles+, 2020)
Observations of disequilibrium CO chemistry in the coldest brown dwarfs.
Miles B.E., Skemer A.J.I., Morley C.V., Marley M.S., Fortney J.J.,
Allers K.N., Faherty J.K., Geballe T.R., Visscher C., Schneider A.C.,
Lupu R., Freedman R.S., Bjoraker G.L.
<Astron. J., 160, 63 (2020)>
=2020AJ....160...63M 2020AJ....160...63M
ADC_Keywords: Stars, brown dwarf; Spectra, infrared
Keywords: Brown dwarfs ; T subdwarfs ; Y dwarfs ; Exoplanets ;
Free floating planets ; Extrasolar gas giants ;
Exoplanet atmospheres ; Planetary atmospheres
Abstract:
Cold brown dwarfs are excellent analogs of widely separated, gas giant
exoplanets, and provide insight into the potential atmospheric
chemistry and physics we may encounter in objects to be discovered by
future direct imaging surveys. We present a low-resolution, R∼300,
M-band spectroscopic sequence of seven brown dwarfs with effective
temperatures between 750 and 250K along with Jupiter. These spectra
reveal disequilibrium abundances of carbon monoxide (CO) produced by
atmospheric quenching. We use the eddy diffusion coefficient (Kzz) to
estimate the strength of vertical mixing in each object. The Kzz
values of cooler gaseous objects are close to their theoretical
maximum, and warmer objects show weaker mixing, likely due to less
efficient convective mixing in primarily radiative layers. The
CO-derived Kzz values imply that disequilibrium phosphine (PH3) should
be easily observable in all of the brown dwarfs, but none as yet show
any evidence for PH3 absorption. We find that ammonia is relatively
insensitive to atmospheric quenching at these effective temperatures.
We are able to improve the fit to WISE 0855's M-band spectrum by
including both CO and water clouds in the atmospheric model.
Description:
We obtained observations of WISE0313, UGPSJ0722, WISE2056, and
WISE1541 over the course of a year at Gemini North (Programs
GN-2016B-Q-23, GN-2017A-Q-5, GN-2017A-Q-32) using the Gemini
near-infrared spectrograph (GNIRS). R∼370. These observations are
complementary to the M-band spectra of WISE0855 published in
Skemer+, 2016ApJ...826L..17S 2016ApJ...826L..17S.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 45 8 Sample of substellar objects with M-band spectra
fig1.dat 41 182 Spectra of the brown dwarves UGPS 0722, WISE 0313,
WISE 1541, and WISE 2056
fig2.dat 41 35 Spectra of the brown dwarf WISE 0855
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/127/3553 : JHK photometry & spectroscopy for L & T dwarfs (Knapp+, 2004)
J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/ApJ/651/502 : Spitzer IRAC photometry of M, L, and T dwarfs (Patten+, 2006)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)
J/ApJ/810/158 : M,L,T dwarfs fundamental param. and SEDs (Filippazzo+, 2015)
J/ApJ/832/58 : Spitzer/IRAC monitor. WISEJ085510.83-071442.5 (Esplin+, 2016)
J/ApJS/225/10 : Kinematic analysis of M7-L8 dwarfs (Faherty+, 2016)
J/ApJ/831/64 : Mass-metallicity relation for giant planets (Thorngren+, 2016)
J/ApJ/842/118 : Brown dwarfs with spectral type later than T6 (Leggett+, 2017)
J/ApJ/838/73 : Brown dwarf surface gravities with Keck/NIRSPEC (Martin, 2017)
J/ApJ/867/109 : Spitzer observations of Y and T dwarfs (Martin+, 2018)
J/A+A/629/A145 : L9-T3.5 brown dwarfs light curves (Eriksson+, 2019)
J/AJ/157/101 : Cloud Atlas: HST/WFC3 NIR spectral library (Manjavacas+, 2019)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Object identifier
18- 20 I3 K Teff [126/750] Adopted temperature
22- 24 I3 K Teffmin [249/716]? Minimum temperature
26- 28 I3 K Teffmax [260/812]? Maximum temperature
30 I1 --- r_Teff Reference used for temperature (1)
32- 35 A4 --- SpT Spectral type
37 I1 --- r_SpT ? Reference used for spectral type (1)
39- 41 F3.1 [cm/s2] loggmin [3.4/4.7] Minimum surface gravity
43- 45 F3.1 [cm/s2] loggmax [3.4/5.4] Maximum surface gravity
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Note (1): References as follows:
1 = Re-fit in this work
2 = Li+, 2012JGRE..11711002L 2012JGRE..11711002L
3 = Burgasser+, 2006, J/ApJ/637/1067
4 = Kirkpatrick+, 2011, J/ApJS/197/19
5 = Cushing+, 2011ApJ...743...50C 2011ApJ...743...50C
6 = Schneider+, 2015ApJ...804...92S 2015ApJ...804...92S
7 = Kirkpatrick+, 2019ApJS..240...19K 2019ApJS..240...19K
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Byte-by-byte Description of file: fig[12].dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Source identifier
18- 24 F7.5 um Wave [4.46/5.13] Wavelength
26- 33 F8.5 cW/m2/nm Flux [-1.05/2]? Normalized flux
in erg/s/cm2/Å units
35- 41 F7.5 cW/m2/nm e_Flux [0.027/1.5]? Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 19-Oct-2020