JWST near-infrared spectroscopy of the Lucy Jupiter Trojan flyby targets: Evidence for OH absorption, aliphatic organics, and CO_2
arxiv(2023)
摘要
We present observations obtained with the Near Infrared Spectrograph on JWST
of the five Jupiter Trojans that will be visited by the Lucy spacecraft – the
Patroclus-Menoetius binary, Eurybates, Orus, Leucus, and Polymele. The measured
1.7-5.3 μm reflectance spectra, which provide increased wavelength
coverage, spatial resolution, and signal-to-noise ratio over previous
ground-based spectroscopy, reveal several distinct absorption features. We
detect a broad OH band centered at 3 μm that is most prominent on the
less-red objects Eurybates, Patroclus-Menoetius, and Polymele. An additional
absorption feature at 3.3-3.6 μm, indicative of aliphatic organics, is
systematically deeper on the red objects Orus and Leucus. The collisional
fragment Eurybates is unique in displaying an absorption band at 4.25 μm
that we attribute to bound or trapped CO_2. Comparisons with other solar
system small bodies reveal broad similarities in the 2.7-3.6 μm bands with
analogous features on Centaurs, Kuiper belt objects (KBOs), and the active
asteroid 238P. In the context of recent solar system evolution models, which
posit that the Trojans initially formed in the outer solar system, the
significant attenuation of the 2.7-3.6 μm absorption features on Trojans
relative to KBOs may be the result of secondary thermal processing of the
Trojans' surfaces at the higher temperatures of the Jupiter region. The CO_2
band manifested on the surface of Eurybates suggests that CO_2 may be a major
constituent in the bulk composition of Trojans, but resides in the subsurface
or deeper interior and is largely obscured by refractory material that formed
from the thermophysical processes that were activated during their inward
migration.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要