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Endogenic and Exogenic Contributions to Visible-wavelength Spectra of Europa’s Trailing Hemisphere

Trumbo, Samantha K. and Brown, Michael E. and Hand, Kevin P. (2020) Endogenic and Exogenic Contributions to Visible-wavelength Spectra of Europa’s Trailing Hemisphere. Astronomical Journal, 160 (6). Art. No. 282. ISSN 1538-3881. doi:10.3847/1538-3881/abc34c.

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The composition of Europa's trailing hemisphere reflects the combined influences of endogenous geologic resurfacing and exogenous sulfur radiolysis. Using spatially resolved visible-wavelength spectra of Europa obtained with the Hubble Space Telescope, we map multiple spectral features across the trailing hemisphere and compare their geographies with the distributions of large-scale geology, magnetospheric bombardment, and surface color. Based on such comparisons, we interpret some aspects of our spectra as indicative of purely exogenous sulfur radiolysis products and other aspects as indicative of radiolysis products formed from a mixture of endogenous material and magnetospheric sulfur. The spatial distributions of two of the absorptions seen in our spectra—a widespread downturn toward the near-UV and a distinct feature at 530 nm—appear consistent with sulfur allotropes previously suggested from ground-based spectrophotometry. However, the geographies of two additional features—an absorption feature at 360 nm and the spectral slope at red wavelengths—are more consistent with endogenous material that has been altered by sulfur radiolysis. We suggest irradiated sulfate salts as potential candidates for this material, but we are unable to identify particular species with the available data.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Trumbo, Samantha K.0000-0002-0767-8901
Brown, Michael E.0000-0002-8255-0545
Hand, Kevin P.0000-0002-3225-9426
Additional Information:© 2020 The American Astronomical Society. Received 2020 May 31; revised 2020 August 30; accepted 2020 September 28; published 2020 November 23. This work is based on observations made with the NASA/ESA HST, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS 5-26555. These observations are associated with program number 14650. This work was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship Program (grant 80NSSC17K0478). Support for this work was provided by NASA through grant No. HST-GO-14650.001-A from the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555. This research was supported by grant 1313461 from the NSF. K.P.H. acknowledges support from the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA and funded, in part, through the internal Research and Technology Development program.
Funding AgencyGrant Number
NASANAS 5-26555
NASA Earth and Space Science Fellowship80NSSC17K0478
JPL Research and Technology Development FundUNSPECIFIED
Subject Keywords:Galilean satellites ; Solar system astronomy ; Surface composition
Issue or Number:6
Classification Code:Unified Astronomy Thesaurus concepts: Galilean satellites (627); Solar system astronomy (1529); Surface composition (2115)
Record Number:CaltechAUTHORS:20201125-132224855
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Official Citation:Samantha K. Trumbo et al 2020 AJ 160 282
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106829
Deposited By: Tony Diaz
Deposited On:25 Nov 2020 23:00
Last Modified:16 Nov 2021 18:57

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