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J/ApJ/832/58 Spitzer/IRAC monitoring of WISE J085510.83-071442.5 (Esplin+, 2016)

Photometric monitoring of the coldest known brown dwarf with the Spitzer Space Telescope. Esplin T.L., Luhman K.L., Cushing M.C., Hardegree-Ullman K.K., Trucks J.L., Burgasser A.J., Schneider A.C. <Astrophys. J., 832, 58-58 (2016)> =2016ApJ...832...58E (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, infrared ; Stars, late-type Keywords: brown dwarfs; infrared: stars; planets and satellites: atmospheres; solar neighborhood; stars: low-mass Abstract: Because WISE J085510.83-071442.5 (hereafter WISE 0855-0714) is the coldest known brown dwarf (∼250K) and one of the Sun's closest neighbors (2.2pc), it offers a unique opportunity to study a planet-like atmosphere in an unexplored regime of temperature. To detect and characterize inhomogeneities in its atmosphere (e.g., patchy clouds, hot spots), we have performed time-series photometric monitoring of WISE 0855-0714 at 3.6 and 4.5µm with the Spitzer Space Telescope during two 23hr periods that were separated by several months. For both bands, we have detected variability with peak-to-peak amplitudes of 4%-5% and 3%-4% in the first and second epochs, respectively. The light curves are semiperiodic in the first epoch for both bands, but they are more irregular in the second epoch. Models of patchy clouds have predicted a large increase in mid-infrared (mid-IR) variability amplitudes (for a given cloud covering fraction) with the appearance of water ice clouds at Teff<375K, so if such clouds are responsible for the variability of WISE 0855-0714, then its small amplitudes of variability indicate a very small deviation in cloud coverage between hemispheres. Alternatively, the similarity in mid-IR variability amplitudes between WISE 0855-0714 and somewhat warmer T and Y dwarfs may suggest that they share a common origin for their variability (i.e., not water clouds). In addition to our variability data, we have examined other constraints on the presence of water ice clouds in the atmosphere of WISE 0855-0714, including the recent mid-IR spectrum from Skemer+ (2016ApJ...826L..17S). We find that robust evidence of such clouds is not yet available. Description: WISE J085510.83-071442.5 was observed continuously during two 23hr periods on 2015 March 10 and 2015 August 3. During each period, we obtained 405 images with exposure times of 96.8s at [4.5], which were immediately followed by 405 images with exposure times of 93.6s at [3.6]. These data were collected through Astronomical Observation Requests 52667904, 52668160, 52668672, and 52668928 within program 11056 (K. Luhman). Objects: ----------------------------------------------------------------------- RA (ICRS) DE Designation(s) ----------------------------------------------------------------------- 08 55 10.83 -07 14 42.5 WISE 0855-0714 = WISE J085510.83-071442.5 ----------------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 25 806 Time-series Photometry for WISE 0855-0714 in [3.6] table2.dat 25 809 Time-series Photometry for WISE 0855-0714 in [4.5]
See also: B/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016) II/311 : WISE All-Sky Data Release (Cutri+ 2012) J/A+A/584/A104 : Luhman 16AB Lucky imaging photom. + astrometry (Mancini+ 2015) J/A+A/566/A111 : Brown dwarf atmosphere monitoring (BAM) (Wilson+, 2014) J/ApJ/781/4 : Photom. of high proper motion objects from WISE (Luhman, 2014) J/AJ/144/148 : IR photometry of brown dwarf and Hyper-LIRG (Griffith+, 2012) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 F10.4 d HMJD Heliocentric Modified Julian Date (G1) 12- 17 F6.3 mag 3.6mag [14.2/17.7] Spitzer/IRAC [3.6] micron band magnitude 19- 23 F5.3 mag e_3.6mag [0.009/0.1] Error in 3.6mag 25 A1 --- f_3.6mag [N/Y] Flagged as outlier in 3.6mag?
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 F10.4 d HMJD Heliocentric Modified Julian Date (G1) 12- 17 F6.3 mag 4.5mag [13.3/14.8] Spitzer/IRAC [4.5] micron band magnitude 19- 23 F5.3 mag e_4.5mag [0.006/0.02] Error in 4.5mag 25 A1 --- f_4.5mag [N/Y] Flagged as outlier in 4.5mag?
Global note: Note (G1): At beginning of observation. Note that photometry is absent for one frame because APEX failed to converge on a measurement.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Feb-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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