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Title: DETECTION OF A HYDROGEN CORONA IN HST Ly α IMAGES OF EUROPA IN TRANSIT OF JUPITER

Abstract

We report far-ultraviolet observations of Europa in transit of Jupiter obtained with the Space Telescope Imaging Spectrograph of the Hubble Space Telescope on six occasions between 2014 December and 2015 March. Absorption of Jupiter’s bright hydrogen Ly α dayglow is detected in a region several moon radii above the limb in all observations. The observed extended absorption provides the first detection of an atomic hydrogen corona around Europa. Molecular constituents in Europa’s global sputtered atmosphere are shown to be optically thin to Ly α . The observations are consistent with a radially escaping H corona with maximum densities at the surface in the range of (1.5–2.2) × 10{sup 3} cm{sup −3}, confirming the abundances predicted by Monte Carlo simulations. In addition, we search for anomalies around the limb of Europa from absorption by localized high H{sub 2}O abundances from active plumes. No significant local absorption features are detected. We find that an H{sub 2}O plume with line-of-sight column density in the order of 10{sup 16} cm{sup −2}, as inferred by Roth et al. would not be detectable based on the statistical fluctuations of the transit measurements, and hence is not excluded or further constrained. The presence of plumes with line-of-sight column densitiesmore » of >2 × 10{sup 17} cm{sup −2} can be excluded at a 3- σ level during five of our six observations.« less

Authors:
; ;  [1]; ; ;  [2];  [3]
  1. KTH Royal Institute of Technology (Sweden)
  2. Southwest Research Institute, San Antonio, TX (United States)
  3. Johns Hopkins University, Baltimore, MD (United States)
Publication Date:
OSTI Identifier:
22663991
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; AIRGLOW; COMPUTERIZED SIMULATION; DENSITY; FAR ULTRAVIOLET RADIATION; FLUCTUATIONS; HYDROGEN; IMAGES; JUPITER PLANET; MONTE CARLO METHOD; MOON; SATELLITE ATMOSPHERES; SPACE; SPUTTERING; SURFACES; TELESCOPES; WATER

Citation Formats

Roth, Lorenz, Ivchenko, Nickolay, Schlatter, Nicola, Retherford, Kurt D., Becker, Tracy M., Grava, Cesare, and Strobel, Darrell F.. DETECTION OF A HYDROGEN CORONA IN HST Ly α IMAGES OF EUROPA IN TRANSIT OF JUPITER. United States: N. p., 2017. Web. doi:10.3847/1538-3881/153/2/67.
Roth, Lorenz, Ivchenko, Nickolay, Schlatter, Nicola, Retherford, Kurt D., Becker, Tracy M., Grava, Cesare, & Strobel, Darrell F.. DETECTION OF A HYDROGEN CORONA IN HST Ly α IMAGES OF EUROPA IN TRANSIT OF JUPITER. United States. doi:10.3847/1538-3881/153/2/67.
Roth, Lorenz, Ivchenko, Nickolay, Schlatter, Nicola, Retherford, Kurt D., Becker, Tracy M., Grava, Cesare, and Strobel, Darrell F.. Wed . "DETECTION OF A HYDROGEN CORONA IN HST Ly α IMAGES OF EUROPA IN TRANSIT OF JUPITER". United States. doi:10.3847/1538-3881/153/2/67.
@article{osti_22663991,
title = {DETECTION OF A HYDROGEN CORONA IN HST Ly α IMAGES OF EUROPA IN TRANSIT OF JUPITER},
author = {Roth, Lorenz and Ivchenko, Nickolay and Schlatter, Nicola and Retherford, Kurt D. and Becker, Tracy M. and Grava, Cesare and Strobel, Darrell F.},
abstractNote = {We report far-ultraviolet observations of Europa in transit of Jupiter obtained with the Space Telescope Imaging Spectrograph of the Hubble Space Telescope on six occasions between 2014 December and 2015 March. Absorption of Jupiter’s bright hydrogen Ly α dayglow is detected in a region several moon radii above the limb in all observations. The observed extended absorption provides the first detection of an atomic hydrogen corona around Europa. Molecular constituents in Europa’s global sputtered atmosphere are shown to be optically thin to Ly α . The observations are consistent with a radially escaping H corona with maximum densities at the surface in the range of (1.5–2.2) × 10{sup 3} cm{sup −3}, confirming the abundances predicted by Monte Carlo simulations. In addition, we search for anomalies around the limb of Europa from absorption by localized high H{sub 2}O abundances from active plumes. No significant local absorption features are detected. We find that an H{sub 2}O plume with line-of-sight column density in the order of 10{sup 16} cm{sup −2}, as inferred by Roth et al. would not be detectable based on the statistical fluctuations of the transit measurements, and hence is not excluded or further constrained. The presence of plumes with line-of-sight column densities of >2 × 10{sup 17} cm{sup −2} can be excluded at a 3- σ level during five of our six observations.},
doi = {10.3847/1538-3881/153/2/67},
journal = {Astronomical Journal (Online)},
number = 2,
volume = 153,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}