TY - JOUR
T1 - Coloring Jupiter's clouds
T2 - Radiolysis of ammonium hydrosulfide (NH4SH)
AU - Loeffler, Mark J.
AU - Hudson, Reggie L.
N1 - Funding Information:
The support of NASA's Planetary Atmospheres and Outer Planets Research programs is gratefully acknowledged. Steve Brown, Tom Ward, and Eugene Gerashchenko, members of the NASA Goddard Radiation Effects Facility, operated and maintained the Van de Graaff accelerator. This work used NASA/ESA Hubble Space Telescope observations retrieved from the Data Archive 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. The observations are associated with programs GO5313, GO11498, and GO13937, and using these program numbers all data can be retrieved from http://archive.stsci.edu/hst/search.php at the Hubble archive.
Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Here we present our recent studies on the color and spectral reflectance changes induced by ∼0.9 MeV proton irradiation of ammonium hydrosulfide, NH4SH, a compound predicted to be an important tropospheric cloud component of Jupiter and other giant planets. Ultraviolet-visible spectroscopy was used to observe and identify reaction products in the ice sample and digital photography was used to document the corresponding color changes at 10–160 K. Our experiments clearly show that the resulting color of the sample depends not only on the irradiation dose but also the irradiation temperature. Furthermore, unlike in our most recent studies of irradiation of NH4SH at 120 K, which showed that higher irradiation doses caused the sample to appear green, the lower temperature studies now show that the sample becomes red after irradiation. However, comparison of these lower temperature spectra over the entire spectral range observed by HST shows that even though the color and spectrum resemble the color and spectrum of the GRS, there is still enough difference to suggest that another component may be needed to adequately fit spectra of the GRS and other red regions of Jupiter's clouds. Regardless, the presence of NH4SH in the atmosphere of Jupiter and other gas giants, combined with this compound's clear alteration via radiolysis, suggests that its contribution to the ultraviolet-visible spectra of any of these object's clouds is significant.
AB - Here we present our recent studies on the color and spectral reflectance changes induced by ∼0.9 MeV proton irradiation of ammonium hydrosulfide, NH4SH, a compound predicted to be an important tropospheric cloud component of Jupiter and other giant planets. Ultraviolet-visible spectroscopy was used to observe and identify reaction products in the ice sample and digital photography was used to document the corresponding color changes at 10–160 K. Our experiments clearly show that the resulting color of the sample depends not only on the irradiation dose but also the irradiation temperature. Furthermore, unlike in our most recent studies of irradiation of NH4SH at 120 K, which showed that higher irradiation doses caused the sample to appear green, the lower temperature studies now show that the sample becomes red after irradiation. However, comparison of these lower temperature spectra over the entire spectral range observed by HST shows that even though the color and spectrum resemble the color and spectrum of the GRS, there is still enough difference to suggest that another component may be needed to adequately fit spectra of the GRS and other red regions of Jupiter's clouds. Regardless, the presence of NH4SH in the atmosphere of Jupiter and other gas giants, combined with this compound's clear alteration via radiolysis, suggests that its contribution to the ultraviolet-visible spectra of any of these object's clouds is significant.
KW - Atmospheres, chemistry
KW - Experimental techniques
KW - Geophysics
KW - Ices, ultraviolet-visible spectroscopy
KW - Jupiter, atmosphere
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U2 - 10.1016/j.icarus.2017.10.041
DO - 10.1016/j.icarus.2017.10.041
M3 - Article
AN - SCOPUS:85037353247
VL - 302
SP - 418
EP - 425
JO - Icarus
JF - Icarus
SN - 0019-1035
ER -