Data Set for "Reconnection preferentially accelerates light ions at Ganymede's magnetopause"

Juno’s flyby of Ganymede revealed ion composition in its vicinity with the JADE-I instrument. By decomposing this data into contributions from individual ion species using species-dependent fits, we derive species-resolved ion densities and velocity moments throughout the flyby. At the upstream magnetopause—a region previously linked to reconnection by both Juno and modeling studies—Juno encountered a strong field-aligned ion jet. Its direction and magnitude are strongly consistent with Hall-mediated flank magnetopause reconnection at Ganymede. As reconnection-accelerated electrons have been associated with Ganymede’s polar aurora, the persistence of auroral emission suggests reconnection, and associated ion acceleration, may occur along an extended X-line. These results imply reconnection at Ganymede can act not only as a localized driver of ion jets, but also as a distributed pathway for ion and neutral loss. Given the appropriate reconnection geometry, such a mechanism is likely operating at a broad range of magnetized astrophysical bodies immersed within plasma.