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Published March 2019 | Erratum + Accepted Version + Published
Journal Article Open

Cloud Atlas: High-contrast Time-resolved Observations of Planetary-mass Companions

Abstract

Directly imaged planetary-mass companions offer unique opportunities in atmospheric studies of exoplanets. They share characteristics of both brown dwarfs and transiting exoplanets, and therefore are critical for connecting atmospheric characterizations for these objects. Rotational phase mapping is a powerful technique to constrain the condensate cloud properties in ultra-cool atmospheres. Applying this technique to directly imaged planetary-mass companions will be extremely valuable for constraining cloud models in low mass and surface-gravity atmospheres and for determining the rotation rate and angular momentum of substellar companions. Here, we present Hubble Space Telescope Wide Field Camera 3 near-infrared time-resolved photometry for three planetary-mass companions, AB Pic B, 2M0122B, and 2M1207b. Using two-roll differential imaging and hybrid point-spread function modeling, we achieve sub-percent photometric precision for all three observations. We find tentative modulations (<2σ) for AB Pic B and 2M0122B, but cannot reach conclusive results on 2M1207b due to strong systematics. The relatively low significance of the modulation measurements cannot rule out the hypothesis that these planetary-mass companions have the same vertical cloud structures as brown dwarfs. Our rotation rate measurements, combined with archival period measurements of planetary-mass companions and brown dwarfs, do not support a universal mass-rotation relation. The high precision of our observations and the high occurrence rates of variable low-surface-gravity objects encourage high-contrast time-resolved observations with the James Webb Space Telescope.

Additional Information

© 2019. The American Astronomical Society. Received 2018 December 6; revised 2019 January 22; accepted 2019 January 29; published 2019 February 28. We thank the referee for a constructive report. We thank Dr. Kaitlin Kratter for pointing out an inadequacy in an earlier version of the manuscript and Dr. Aleks Scholz for useful comments. Y.Z. acknowledges support in part by the NASA Earth and Space Science Fellowship Program—Grant NNX16AP54H. D.A. acknowledges support by NASA under agreement no. NNX15AD94G for the program Earths in Other Solar Systems. Support for program no. 14241 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained in GO program 14241 at the Space Telescope Science Institute. Software: Numpy&Scipy (van der Walt et al. 2011), Matplotlib (Hunter 2007), IPython (Perez & Granger 2007), Astropy (Robitaille et al. 2013), Seaborn (Waskom et al. 2017).

Attached Files

Published - Zhou_2019_AJ_157_128.pdf

Accepted Version - 1902.00085.pdf

Erratum - Zhou_2019_AJ_158_52.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023