Constraints on Europa's water group torus from HST/COS observations
In-situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter provide indirect evidence that an enhancement of neutral gas is present near the orbit of the moon Europa. Simulations suggest that such a neutral gas torus can be sustained by escape from Europa's a...
Gespeichert in:
Hauptverfasser: | , , , , , , , , , , |
---|---|
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext bestellen |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | In-situ plasma measurements as well as remote mapping of energetic neutral
atoms around Jupiter provide indirect evidence that an enhancement of neutral
gas is present near the orbit of the moon Europa. Simulations suggest that such
a neutral gas torus can be sustained by escape from Europa's atmosphere and
consists primarily of molecular hydrogen, but the neutral gas torus has not yet
been measured directly through emissions or in-situ. Here we present
observations by the Cosmic Origins Spectrograph of the Hubble Space Telescope
(HST/COS) from 2020 and 2021, which scanned the equatorial plane between 8 and
10 planetary radii west of Jupiter. No neutral gas emissions are detected. We
derive upper limits on the emissions and compare these to modelled emissions
from electron impact and resonant scattering using a Europa torus Monte Carlo
model for the neutral gases. The comparison supports the previous findings that
the torus is dilute and primarily consists of molecular hydrogen. A detection
of sulfur ion emissions radially inward of the Europa orbit is consistent with
emissions from the extended Io torus and with sulfur ion fractional abundances
as previously detected. |
---|---|
DOI: | 10.48550/arxiv.2304.09150 |