Variation of Jupiter's aurora observed by Hisaki/EXCEED: 1. Observed characteristics of the auroral electron energies compared with observations performed using HST/STIS

Chihiro Tao (1) , Tomoki Kimura , Sarah V. Badman , Go Murakami , Kazuo Yoshioka , Fuminori Tsuchiya , Nicolas André (1) , Ichiro Yoshikawa , Atsushi Yamazaki , Daikou Shiota , Hiroyasu Tadokoro , Masaki Fujimoto

1 IRAP - Institut de recherche en astrophysique et planétologie

Temporal variation of Jupiter's northern aurora is detected using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) on board JAXA's Earth-orbiting planetary space telescope Hisaki. The wavelength coverage of EXCEED includes the H₂ Lyman and Werner bands at 80-148 nm from the entire northern polar region. The prominent periodic modulation of the observed emission corresponds to the rotation of Jupiter's main auroral oval through the aperture, with additional superposed -50%-100% temporal variations. The hydrocarbon color ratio (CR) adopted for the wavelength range of EXCEED is defined as the ratio of the emission intensity in the long wavelength range of 138.5-144.8 nm to that in the short wavelength range of 126.3-130 nm. This CR varies with the planetary rotation phase. Short- (within one planetary rotation) and long-term (> one planetary rotation) enhancements of the auroral power are observed in both wavelength ranges and result in a small CR variation. The occurrence timing of the auroral power enhancement does not clearly depend on the central meridian longitude. Despite the limitations of the wavelength coverage and the large field of view of the observation, the auroral spectra and CR-brightness distribution measured using EXCEED are consistent with other observations.

Keywords: Jupiter; aurora; Hisaki; EXCEED; Hubble Space Telescope

Domains: Sciences of the Universe [physics]

Chihiro Tao, Tomoki Kimura, Sarah V. Badman, Go Murakami, Kazuo Yoshioka, et al.. Variation of Jupiter's aurora observed by Hisaki/EXCEED: 1. Observed characteristics of the auroral electron energies compared with observations performed using HST/STIS. Journal of Geophysical Research: Space Physics, 2016, 121, pp.4041-4054. ⟨10.1002/2015JA021271⟩. ⟨insu-03670235⟩