MESSENGER Observations of Planetary Ion Enhancements at Mercury's Northern Magnetospheric Cusp During Flux Transfer Event Showers.

At Mercury, several processes can release ions and neutrals out of the planet's surface. Here we present enhancements of planetary ions (Na-group ions) in Mercury's northern magnetospheric cusp during flux transfer event (FTE) "showers." FTE showers are intervals of intense dayside magnetopause reconnection, during which FTEs are observed in quick succession, that is, only separated by a few seconds.

Photoionization Loss of Mercury's Sodium Exosphere: Seasonal Observations by MESSENGER and the THEMIS Telescope.

We present the first investigation and quantification of the photoionization loss process to Mercury's sodium exosphere from spacecraft and ground-based observations. We analyze plasma and neutral sodium measurements from NASA's MESSENGER spacecraft and the THEMIS telescope. We find that the sodium ion (Na) content and therefore the significance of photoionization varies with Mercury's orbit around the Sun (i.

A transient enhancement of Mercury's exosphere at extremely high altitudes inferred from pickup ions.

Mercury has a global dayside exosphere, with measured densities of 10 cm at ~1500 km. Here we report on the inferred enhancement of neutral densities (<10 cm) at high altitudes (~5300 km) by the MESSENGER spacecraft. Such high-altitude densities cannot be accounted for by the typical exosphere.

The impact of an ICME on the Jovian X-ray aurora.

We report the first Jupiter X-ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X-ray aurora. Within 1.