TY - JOUR
T1 - Evidence for OH or H2O on the surface of 433 Eros and 1036 Ganymed
AU - Rivkin, Andrew S.
AU - Howell, Ellen S.
AU - Emery, Joshua P.
AU - Sunshine, Jessica
N1 - Funding Information:
ASR gratefully acknowledges consistent support from NSF Planetary Astronomy Program grants 1009710 and 1313144 and from NASA Near Earth Observations grant NNX14AL60G . Contributions by JPE were funded through NASA Solar System Observations grant NN16AE91G and the NASA Spitzer Space Telescope through an award issued by JPL / Caltech . We acknowledge the sacred nature of Maunakea to many Hawaiians, and our status as guests who have been privileged to work there. Many thanks to the stalwart telescope operators of the IRTF who were instrumental in taking these data through the years, and to Bobby Bus and Eric Volquardsen for developing the “ATRAN part” of the data reduction. Thanks to Carolyn Ernst for useful discussions about the non-intuitive behavior of latitudes and longitudes on irregular small bodies and help with the Small Body Mapping Tool. Reviews by anonymous referees helped strengthen this work, and credit is due to them, whoever they are.
Funding Information:
ASR gratefully acknowledges consistent support from NSF Planetary Astronomy Program grants 1009710 and 1313144 and from NASA Near Earth Observations grant NNX14AL60G. Contributions by JPE were funded through NASA Solar System Observations grant NN16AE91G and the NASA Spitzer Space Telescope through an award issued by JPL/Caltech. We acknowledge the sacred nature of Maunakea to many Hawaiians, and our status as guests who have been privileged to work there. Many thanks to the stalwart telescope operators of the IRTF who were instrumental in taking these data through the years, and to Bobby Bus and Eric Volquardsen for developing the ?ATRAN part? of the data reduction. Thanks to Carolyn Ernst for useful discussions about the non-intuitive behavior of latitudes and longitudes on irregular small bodies and help with the Small Body Mapping Tool. Reviews by anonymous referees helped strengthen this work, and credit is due to them, whoever they are.
Publisher Copyright:
© 2017
PY - 2018/4
Y1 - 2018/4
N2 - Water and hydroxyl, once thought to be found only in the primitive airless bodies that formed beyond roughly 2.5–3 AU, have recently been detected on the Moon and Vesta, which both have surfaces dominated by evolved, non-primitive compositions. In both these cases, the water/OH is thought to be exogenic, either brought in via impacts with comets or hydrated asteroids or created via solar wind interactions with silicates in the regolith or both. Such exogenic processes should also be occurring on other airless body surfaces. To test this hypothesis, we used the NASA Infrared Telescope Facility (IRTF) to measure reflectance spectra (2.0–4.1 µm) of two large near-Earth asteroids (NEAs) with compositions generally interpreted as anhydrous: 433 Eros and 1036 Ganymed. OH is detected on both of these bodies in the form of absorption features near 3 µm. The spectra contain a component of thermal emission at longer wavelengths, from which we estimate thermal inertias of 167 ± 98 J m−2s−1/2K−1 for Eros (consistent with previous estimates) and 214 ± 80 J m−2s−1/2K−1 for Ganymed, the first reported measurement of thermal inertia for this object. These observations demonstrate that processes responsible for water/OH creation on large airless bodies also act on much smaller bodies.
AB - Water and hydroxyl, once thought to be found only in the primitive airless bodies that formed beyond roughly 2.5–3 AU, have recently been detected on the Moon and Vesta, which both have surfaces dominated by evolved, non-primitive compositions. In both these cases, the water/OH is thought to be exogenic, either brought in via impacts with comets or hydrated asteroids or created via solar wind interactions with silicates in the regolith or both. Such exogenic processes should also be occurring on other airless body surfaces. To test this hypothesis, we used the NASA Infrared Telescope Facility (IRTF) to measure reflectance spectra (2.0–4.1 µm) of two large near-Earth asteroids (NEAs) with compositions generally interpreted as anhydrous: 433 Eros and 1036 Ganymed. OH is detected on both of these bodies in the form of absorption features near 3 µm. The spectra contain a component of thermal emission at longer wavelengths, from which we estimate thermal inertias of 167 ± 98 J m−2s−1/2K−1 for Eros (consistent with previous estimates) and 214 ± 80 J m−2s−1/2K−1 for Ganymed, the first reported measurement of thermal inertia for this object. These observations demonstrate that processes responsible for water/OH creation on large airless bodies also act on much smaller bodies.
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U2 - 10.1016/j.icarus.2017.04.006
DO - 10.1016/j.icarus.2017.04.006
M3 - Article
AN - SCOPUS:85018624916
SN - 0019-1035
VL - 304
SP - 74
EP - 82
JO - Icarus
JF - Icarus
ER -