J/AJ/164/65 NIR light curve of 2MASS J00501994-3322402 (Manjavacas+, 2022)
Top-of-the-atmosphere and Vertical Cloud Structure of a Fast-rotating Late T
Dwarf.
Manjavacas E., Karalidi T., Tan X., Vos J.M., Lew B.W.P., Biller B.A.,
Oliveros-Gomez N.
<Astron. J., 164, 65 (2022)>
=2022AJ....164...65M 2022AJ....164...65M
ADC_Keywords: Stars, T-type; Stars, brown dwarf; Spectra, infrared
Keywords: T dwarfs ; Atmospheric variability
Abstract:
Only a handful of late T brown dwarfs have been monitored for
spectrophotometric variability, leaving incomplete the study of the
atmospheric cloud structures of the coldest brown dwarfs, which share
temperatures with some cold, directly imaged exoplanets.
2MASS J00501994-332240 is a T7.0 rapidly rotating, field brown dwarf
that showed low-level photometric variability in data obtained with
the Spitzer Space Telescope. We monitored 2MASS J00501994-332240
during ∼2.6hr with MOSFIRE, installed at the Keck I telescope, with
the aim of constraining its near-infrared spectrophotometric
variability. We measured fluctuations with a peak-to-peak amplitude of
1.48%±0.75% in the J-band photometric light curve, an amplitude of
0.62%±0.18% in the J-band spectrophotometric light curve, an
amplitude of 1.26%±0.93% in the H-band light curve, and an
amplitude of 5.33%±2.02% in the CH4-H2O band light curve.
Nevertheless, the Bayesian information criterion does not detect
significant variability in any of the light curves. Thus, given the
detection limitations due to the MOSFIRE sensitivity, we can only
claim tentative low-level variability for 2M0050-3322 in the best-case
scenario. The amplitudes of the peak-to-peak fluctuations measured for
2MASS J00501994-332240 agree with the variability amplitude
predictions of general circulation models for a T7.0 brown dwarf for
an edge-on object. Radiative transfer models predict that the Na2S and
KCl clouds condense at pressures lower than that traced by the CH4-H2O
band, which might explain the higher peak-to-peak fluctuations
measured for this light curve. Finally, we provide a visual recreation
of the map provided by general circulation models and the vertical
structure of 2MASS J00501994-332240 provided by radiative transfer
models.
Description:
Near-infrared multiobject spectrographs like MOSFIRE, installed at the
Keck I telescope, allow us to perform spectrophotometric monitoring of
brown dwarfs from the ground. We obtained three spectra of
2M0050-3322 in the J-band using a 1.5" ABBA pattern. We used wide
slits of 4.5" to avoid slit losses for all calibration stars and the
target, obtaining a spectral resolution of R∼1000. Immediately, we
obtained another nine spectra in the H-band during ∼1.4hr, covering
the second rotational period of 2M0050-3322.
Objects:
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RA (2000) DE Designation(s)
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00 50 19.94 -33 22 40.3 2MASS J00501994-3322402 = 2MASS J00501994-3322402
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig7a.dat 35 22 Photometric J-band light curve, spectrophotometric
J-band light curve, and H-band light curve
fig7b.dat 35 22 J-band photometric, J-band spectrophotometric, and
CH4-H2O spectrophotometric light curve
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/429/1007 : RIJHK photometry of VLM objects near eps Ori (Scholz+, 2005)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/ApJS/214/25 : Rosseland & Planck gaseous mean opacities (Freedman+, 2014)
J/ApJ/810/158 : M,L,T dwarfs fundamental parameters & SEDs (Filippazzo+, 2015)
J/other/Sci/350.64 : 51 Eri b near-infrared spectrum (Macintosh+, 2015)
J/AJ/160/38 : Spitzer variability detections of 79 brown dwarfs (Vos+, 2020)
Byte-by-byte Description of file: fig7[ab].dat
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Bytes Format Units Label Explanations
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1- 11 E11.5 hr Time Time
13- 23 E11.5 --- Flux Flux density; normalized Flux
25- 35 E11.5 --- e_Flux Uncertainty of normalized Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Oct-2022