Simultaneous Multiwavelength Variability Characterization of the Free-floating Planetary-mass Object PSO J318.5−22
Name
Biller_2018_AJ_155_95.pdf
Size
7.99 MB
Format
Adobe PDF
Checksum (MD5)
a9f4360bf8c201be77013e169090c0cd
Author(s)
Biller, Beth A.
Vos, Johanna
Buenzli, Esther
Allers, Katelyn
Bonnefoy, Mickaël
Charnay, Benjamin
Bézard, Bruno
Allard, France
Homeier, Derek
Bonavita, Mariangela
Date Issued
January 2018
Journal
Astronomical Journal
Publisher
American Astronomical Society
Citation
Biller, Beth A. et al. “Simultaneous Multiwavelength Variability Characterization of the Free-Floating Planetary-Mass Object PSO J318.5−22.” The Astronomical Journal 155, 2 (January 2018): 95 © 2018 American Astronomical Society
Version
Final published version
Abstract
We present simultaneous Hubble Space Telescope (HST) WFC3+Spitzer IRAC variability monitoring for the highly variable young (∼20 Myr) planetary-mass object PSO J318.5-22. Our simultaneous HST + Spitzer observations covered approximately two rotation periods with Spitzer and most of a rotation period with the HST. We derive a period of 8.6 ± 0.1 hr from the Spitzer light curve. Combining this period with the measured for this object, we find an inclination of 56.°2 ± 8.°1. We measure peak-to-trough variability amplitudes of 3.4% ± 0.1% for Spitzer Channel 2 and 4.4%-5.8% (typical 68% confidence errors of ∼0.3%) in the near-IR bands (1.07-1.67 μm) covered by the WFC3 G141 prism - the mid-IR variability amplitude for PSO J318.5-22 is one of the highest variability amplitudes measured in the mid-IR for any brown dwarf or planetary-mass object. Additionally, we detect phase offsets ranging from 200° to 210° (typical error of ∼4°) between synthesized near-IR light curves and the Spitzer mid-IR light curve, likely indicating depth-dependent longitudinal atmospheric structure in this atmosphere. The detection of similar variability amplitudes in wide spectral bands relative to absorption features suggests that the driver of the variability may be inhomogeneous clouds (perhaps a patchy haze layer over thick clouds), as opposed to hot spots or compositional inhomogeneities at the top-of-atmosphere level.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/1538-3881/AAA5A6
