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Title: HST Rotational Spectral Mapping Of Two L-Type Brown Dwarfs: Variability In And Out Of Water Bands Indicates High-Altitude Haze Layers

Journal Article · · The Astrophysical Journal. Letters (Online)
 [1];  [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [1];  [1];  [1];  [12]
  1. Univ. of Arizona, Tucson, AZ (United States)
  2. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. of California, Santa Cruz, CA (United States)
  5. Max Planck Inst. for Astronomy, Heidelberg (Germany)
  6. Univ. of Montreal, Quebec (Canada)
  7. Space Telescope Inst., Baltimore, MD (United States)
  8. Western Univ. London, ON (Canada)
  9. Univ. of California, San Diego, CA (United States)
  10. Imperial College, London (United Kingdom)
  11. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  12. State Univ. of New York (SUNY), Stony Brook, NY (United States)
+ Show Author Affiliations

We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 μm and 1.7 μm. We find that the water absorption bands of the two L5 dwarfs at 1.15 μm and 1.4 μm vary at similar amplitudes as the adjacent continuum. This differs from the results of previous HST observations of L/T transition dwarfs, in which the water absorption at 1.4 μm displays variations of about half of the amplitude at other wavelengths. We find that the relative amplitude of flux variability out of the water band with respect to that in the water band shows a increasing trend from the L5 dwarfs toward the early T dwarfs. We utilize the models of Saumon & Marley (2008) and find that the observed variability of the L5 dwarfs can be explained by the presence of spatially varying high-altitude haze layers above the condensate clouds. Therefore, our observations show that the heterogeneity of haze layers - the driver of the variability - must be located at very low pressures, where even the water opacity is negligible. In the near future, the rotational spectral mapping technique could be utilized for other atomic and molecular species to probe different pressure levels in the atmospheres of brown dwarfs and exoplanets and uncover both horizontal and vertical cloud structures.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1239266
Report Number(s):
LA-UR-14-27992
Journal Information:
The Astrophysical Journal. Letters (Online), Vol. 798, Issue 1; ISSN 2041-8213
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 42 works
Citation information provided by
Web of Science

References (39)

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Cited By (21)

First light of the VLT planet finder SPHERE: IV. Physical and chemical properties of the planets around HR8799⋆ journal February 2016
AEOLUS : A MARKOV CHAIN MONTE CARLO CODE FOR MAPPING ULTRACOOL ATMOSPHERES. AN APPLICATION ON JUPITER AND BROWN DWARF HST LIGHT CURVES journal November 2015
SPITZER SPACE TELESCOPE MID-IR LIGHT CURVES OF NEPTUNE journal October 2016
Simultaneous Multiwavelength Variability Characterization of the Free-floating Planetary-mass Object PSO J318.5−22 journal January 2018
Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B journal February 2018
The Near-infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-epoch Transit Spectra journal October 2018
Cloud Atlas: Hubble Space Telescope Near-infrared Spectral Library of Brown Dwarfs, Planetary-mass Companions, and Hot Jupiters journal February 2019
Cloud Atlas: High-contrast Time-resolved Observations of Planetary-mass Companions journal February 2019
A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds journal February 2017
Cloud Atlas: Variability in and out of the Water Band in the Planetary-mass HD 203030B Points to Cloud Sedimentation in Low-gravity L Dwarfs journal October 2019
Cloud Atlas: Rotational Spectral Modulations and Potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C journal April 2019
Cloud Atlas: Hubble Space Telescope Near-infrared Spectral Library of Brown Dwarfs, Planetary-mass Companions, and Hot Jupiters text January 2019
The exoplanet handbook: Book Review journal March 2012
Cloud Atlas: Hubble Space Telescope Near-infrared Spectral Library of Brown Dwarfs, Planetary-mass Companions, and Hot Jupiters text January 2019
First light of the VLT planet finder SPHERE. IV. Physical and chemical properties of the planets around HR8799 text January 2015
$Extrasolar~Storms$: Pressure-dependent Changes In Light Curve Phase In Brown Dwarfs From Simultaneous $Hubble$ and $Spitzer$ Observations text January 2016
Spitzer Space Telescope Mid-IR Light Curves of Neptune text January 2016
A Condensation-Coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds text January 2017
Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B text January 2018
The Near-Infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-Epoch Transit Spectra text January 2018
Cloud Atlas: Variability in and out of the Water Band in the Planetary-mass HD 203030B Points to Cloud Sedimentation in Low-gravity L Dwarfs text January 2019

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