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Science. 2020 Feb 13. pii: eaay3705. doi: 10.1126/science.aay3705. [Epub ahead of print]

Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth.

Author information

1
Lowell Observatory, Flagstaff, AZ 86001, USA. w.grundy@lowell.edu.
2
Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ 86011, USA.
3
Argelander-Institut für Astronomie, University of Bonn, D-53121 Bonn, Germany.
4
Rheinisches Institut für Umweltforschung, Universität zu Köln, 50931 Cologne, Germany.
5
University of Central Florida, Orlando, FL 32816, USA.
6
Pinhead Institute, Telluride, CO 81435, USA.
7
NASA Ames Research Center, Moffett Field, CA 94035, USA.
8
Southwest Research Institute, Boulder, CO 80302, USA.
9
Steward Observatory, University of Arizona, Tucson, AZ 85719, USA.
10
Stanford University, Stanford, CA 94305, USA.
11
Carl Sagan Center, SETI Institute, Mountain View, CA 94043, USA.
12
National Research Council, Victoria, BC V9E 2E7, Canada.
13
Department of Physics and Astronomy, University of Victoria, Victoria, BC V8W 2Y2, Canada.
14
California Institute of Technology, Pasadena, CA 91125, USA.
15
University of Virginia, Charlottesville, VA 22904, USA.
16
Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
17
Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
18
NASA Jet Propulsion Laboratory, La Cañada Flintridge, CA 91011, USA.
19
Southwest Research Institute, San Antonio, TX 78238, USA.
20
Institut de Planétologie et d'Astrophysique de Grenoble, Centre National de la Recherche Scientifique, Université Grenoble Alpes, Grenoble, France.
21
University of Colorado, Boulder, CO 80309, USA.
22
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
23
Princeton University, Princeton, NJ 08544, USA.
24
Washington University, St. Louis, MO 63130, USA.
25
Lunar and Planetary Institute, Houston, TX 77058, USA.
26
Big Head Endian LLC, Leawood, KS 67019, USA.

Abstract

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We study its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. H2O ice is not detected. This composition indicates hydrogenation of CO-rich ice and/or energetic processing of CH4+H2O ices in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, suggesting Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 K.

PMID:
32054693
DOI:
10.1126/science.aay3705

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