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Title: Near-infrared brightness of the Galilean satellites eclipsed in Jovian shadow: A new technique to investigate Jovian upper atmosphere

Based on observations from the Hubble Space Telescope and the Subaru Telescope, we have discovered that Europa, Ganymede, and Callisto are bright around 1.5 μm even when not directly lit by sunlight. The observations were conducted with non-sidereal tracking on Jupiter outside of the field of view to reduce the stray light subtraction uncertainty due to the close proximity of Jupiter. Their eclipsed luminosity was 10{sup –6}-10{sup –7} of their uneclipsed brightness, which is low enough that this phenomenon has been undiscovered until now. In addition, Europa in eclipse was <1/10 of the others at 1.5 μm, a potential clue to the origin of the source of luminosity. Likewise, Ganymede observations were attempted at 3.6 μm by the Spitzer Space Telescope, but it was not detected, suggesting a significant wavelength dependence. It is still unknown why they are luminous even when in the Jovian shadow, but forward-scattered sunlight by hazes in the Jovian upper atmosphere is proposed as the most plausible candidate. If this is the case, observations of these Galilean satellites while eclipsed by the Jovian shadow provide us with a new technique to investigate the Jovian atmospheric composition. Investigating the transmission spectrum of Jupiter by this method ismore » important for investigating the atmosphere of extrasolar giant planets by transit spectroscopy.« less
Authors:
 [1] ; ; ; ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ; ;  [7] ;  [8] ;  [9] ;  [10]
  1. Frontier Research Institute for Interdisciplinary Science, Tohoku University, Sendai, Miyagi 980-8578 (Japan)
  2. Department of Space Astronomy and Astrophysics, Institute of Space and Astronoutical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210 (Japan)
  3. Department of Astronomy, Arizona University, Tucson, AZ 85721 (United States)
  4. Hawaii Observatory, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States)
  5. Research Center for Advanced Information Science and Technology, Aizu Research Cluster for Space Science, The University of Aizu, Aizu-Wakamatsu, Fukushima 965-8589 (Japan)
  6. Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550 (Japan)
  7. Department of Cosmosciences, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan)
  8. Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581 (Japan)
  9. Department of Earth and Planetary Sciences, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8551 (Japan)
  10. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22365700
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; 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; ATMOSPHERES; BRIGHTNESS; ECLIPSE; FREQUENCY DEPENDENCE; LUMINOSITY; NEAR INFRARED RADIATION; SATELLITES; SPACE; SPECTRA; SPECTROSCOPY; TELESCOPES; TRANSMISSION; VISIBLE RADIATION