Spatially resolved HST/STIS observations of Io’s dayside equatorial atmosphere

Jessup, Kandis Lea; Spencer, J. R.

doi:10.1016/j.icarus.2014.10.020

Cited by 21 publications

(22 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our peak values are also in general agreement with HST/STIS spectroscopic results from observations in late 2001 (Jessup et al 2004, their Fig. 8) and 2010(Jessup and Spencer 2015their Fig. 13), and with HST/COS data from 2010 (Tsang et al 2013a); in particular Jessup and Spencer (2015) determine maximum zero-latitude SO2 column densities of ~ (2.0-2.5) x 10 17 cm -2 , occurring at L =170.…”

Section: So2 Distribution and Volcanic Vs Sublimation Atmospheresupporting

confidence: 90%

Detection and characterization of Io’s atmosphere from high-resolution 4-μm spectroscopy

Lellouch

Ali-Dib

Jessup

et al. 2015

Icarus

View full text Add to dashboard Cite

We report on high-resolution and spatially-resolved spectra of Io in the 4.0 µm region, recorded with the VLT/CRIRES instrument in 2008 and 2010, which provide the first detection of the 1+3 band of SO2 in Io's atmosphere. Data are analyzed to constrain the latitudinal, longitudinal, and diurnal distribution of Io's SO2 atmosphere as well as its characteristic temperature. equatorial SO2 column densities clearly show longitudinal asymmetry, but with a maximum of ~1.5x10 17 cm -2 at central meridian longitude L = 200-220 and a minimum of ~3x10 16 cm -2 at L = 285-300, the longitudinal pattern somewhat differs from earlier inferences from Ly α and thermal IR measurements. Within the accuracy of the measurements, no evolution of the atmospheric density from mid-2008 to mid-2010 can be distinguished. The decrease of the SO2 column density towards high latitude is apparent, and the typical latitudinal extent of the atmosphere found to be ±40° at half-maximum. The data show moderate diurnal variations of the equatorial atmosphere, which is evidence for a partially sublimation-supported atmospheric component. Compared to local noon, factor of 2 lower densities are observed ~40° before and ~80° after noon. Best-fit gas temperatures range from 150 to 220 K, with a weighted mean value of 170±20 K, which should represent the column-weighted mean kinetic temperature of Io's atmosphere. Finally, although the data include clear thermal emission due to Pillan (in outburst in July 2008) and Loki, no detectable 1 enhancements in the SO2 atmosphere above these volcanic regions are found, with an upper limit of 4x10 16 cm -2 at Pillan and 1x10 17 cm -2 at Loki. Highlights:-The first detection of Io's SO2 atmosphere at 4.0 µm is reported, providing a new window for Io's atmospheric studies. -Our spatially-resolved data permit us to a detailed characterization of Io's atmosphere. -Longitudinal, diurnal, and latitudinal variations are observed.-A mean gas temperature of ~170 K is determined.2

show abstract

Section: So2 Distribution and Volcanic Vs Sublimation Atmospheresupporting

confidence: 90%

Detection and characterization of Io’s atmosphere from high-resolution 4-μm spectroscopy

Lellouch

Ali-Dib

Jessup

et al. 2015

Icarus

View full text Add to dashboard Cite

show abstract

“…Similar HST/STIS near-UV observations of the latitudinal dependence of atmospheric density (Jessup et al, 2004;Jessup and Spencer, 2013) show that the latitude dependence observed at low latitudes closely follows expectations for an atmosphere in vapor pressure equilibrium that varies with frost temperature.…”

Section: Spatial Distribution Of Io's Atmospheresupporting

confidence: 68%

“…However, Lyman-a brightness at low latitudes was also observed not to increase between the center of the disk and the equatorial limb (Feldman et al, 2000), implying that the atmosphere does not vary greatly with local time. This behavior is also supported by the analysis of spatially resolved HST/STIS near-UV spectroscopy of SO 2 absorption bands, primarily between 2100 and 2300 Å, taken in 2011 and 2012, which showed that the low-latitude atmospheric density inferred from observations taken at central meridian longitude (CML) 200 W and 250 W varied little with local time at a given longitude (Jessup and Spencer, 2013). If the atmosphere is sublimation dominated, this behavior can only be explained if the sublimating frost has high thermal inertia.…”

Section: Spatial Distribution Of Io's Atmospherementioning

confidence: 60%

Non-detection of post-eclipse changes in Io’s Jupiter-facing atmosphere: Evidence for volcanic support?

Tsang

Spencer

Jessup

2015

Icarus

Self Cite

View full text Add to dashboard Cite

“…The column density of Io's atmosphere outside of eclipse is not tightly constrained. As reviewed by Blöcker et al () observations of Io's atmosphere indicate that Io's equatorial dayside SO 2 column density ranges from 1 × 10 20 to 22 × 10 20 m 2 for various heliospheric distances and local times and based on different types of observational techniques (Feaga et al, ; Jessup et al, ; Jessup & Spencer, ; Lellouch et al, ; McGrath et al, ; Spencer et al, ; Tsang et al, ). The relative role of Io's sublimation‐driven atmosphere compared to its volcanically driven atmosphere, which controls the possible decrease during eclipse, is also not well constrained in the literature.…”

Section: Modulation Of the Electrodynamic Interaction By Io's Atmosphmentioning

confidence: 99%

Juno‐UVS Observation of the Io Footprint During Solar Eclipse

et al. 2019

View full text Add to dashboard Cite

The two main ultraviolet‐signatures resulting from the Io‐magnetosphere interaction are the local auroras on Io's atmosphere, and the Io footprints on Jupiter. We study here how Io's daily eclipses affect the footprint. Previous observations showed that its atmosphere collapses in eclipse. While remote observers can observe Io's local auroras briefly when Io disappears behind Jupiter, Juno is able to follow the Io footprint in the unlit hemisphere. Theoretical models of the variability of the energy flux fed into the Alfvén wings, ultimately powering the footprints, are not sufficiently constrained by observations. For the first time, we use observations of Io's footprint from the Ultraviolet Spectrograph (UVS) on Juno recorded as Io went into eclipse. We benchmark the trend of the footprint brightness using observations by UVS taken over Io's complete orbit and find that the footprint emitted power variation with Jupiter's rotation shows fairly consistent trends with previous observations. Two exploitable data sets provided measurements when Io was simultaneously in eclipse. No statistically significant changes were recorded as Io left and moved into eclipse, respectively, suggesting either that (i) Io's atmospheric densities within and outside eclipse are large enough to produce a saturated plasma interaction, that is, in the saturated state, changes in Io's atmospheric properties to first order do not control the total Alfvénic energy flux, (ii) the atmospheric collapse during the Juno observations was less than previously observed, or (iii) additional processes of the Alfvén wings in addition to the Poynting flux generated at Io control the footprint luminosity.

show abstract

Spatially resolved HST/STIS observations of Io’s dayside equatorial atmosphere

Cited by 21 publications

References 53 publications

Detection and characterization of Io’s atmosphere from high-resolution 4-μm spectroscopy

Detection and characterization of Io’s atmosphere from high-resolution 4-μm spectroscopy

Non-detection of post-eclipse changes in Io’s Jupiter-facing atmosphere: Evidence for volcanic support?

Juno‐UVS Observation of the Io Footprint During Solar Eclipse

Contact Info

Product

Resources

About