Impact of 's volcanic activity to environment and dynamics in the Jovian : from HISAKI results

F. Tsuchiya(1) , K. Yoshioka(2), T. Kimura(1), G. Murakami(3), A. Yamazaki(3), M. Kagitani(1), C. Tao(4), H. Kita(3), R. Koga(1), F. Suzuki(2), R. Hikida(2), Y. Kasaba(1), H. Misawa(1), and T. Sakanoi(1), I. Yoshikawa(2)

(1)Tohoku Univ., (2)Univ. Tokyo, (3)ISAS/JAXA, (4)NICT - Launch : Sep 14, 2013, The Hisaki satellite - Size：1m×1m×4m - Orbit：950km×1150km (LEO) EUV spectrograph (EXCEED): Major specifications - Inclination: 30 deg - Wavelength range: 55-145nm - Orbital period : 106 min - Spectral resolution: 0.4-1.0nm Difficult to observe a moon itself - Spatial coverage ~370 arc-sec But designed to observed - Spatial resolution : 17 arc-sec torus and simultaneously

Allowed transition lines of FUV/EUV aurora S,O ions (satellite origin) H2 Lyman & Werner bands

Mission periods Aurora & gas torus slit Energy flow from outer to inner part of magnetosphere (Primary) 2013-09 - 2014-11 (Extended 1) 2014-12 - 2017-03 (Extended 2) 2017-04 - 2020-03 Yoshioka et al. 2013, Yoshikawa et al. 2014, Yamazaki et al. 2014 2 Summary of the HISAKI findings • 1. Internally driven energy release process & inward transport of the energy Yoshioka et al. 2014, Kimura et al. 2015, Badman et al. 2015, Yoshikawa et al. 2016, 2017, Suzuki et al. 2018 2. Solar influence on the magnetosphere (plasma torus, radiation belt, and aurora) Kimura et al. 2016, Tao et al. 2016a, 2016b, Kita et al. 2016, Murakami et al. 2016, Han et al. 2018, Kita et al. 2019 3. Mass input (from volcanos at Io) to the magnetosphere Yoneda et al. 2015, Kimura et al. 2018, Tao et al. 2018, Tsuchiya et al. 2018, Yoshioka et al. 2018, Koga et al. 2018a, 2018b 4. Plasma heating due to Satellite(Io)-magnetosphere interaction Tsuchiya et al. 2015 5. New plasma torus lines and energy states: Hikida et al. 2018 • Venus • Periodic air grow: Masunaga et al. 2015, 2017

• Detection of N2 LBH Bands: Nara et al. 2018 • ：Enceradus oxygen gas torus • Geocorona： response Kuwabara et al. 2016 • Marcury’s exosphere, Comet coma and tail • EUV stars, Intersteller wind (He cone） 3 Jupiter: Rotation dominant magnetosphere Io - Strongest magnetic field - Rapid rotation (~10 hours) - Dominant plasma source at Io (1ton/s, 90% of mass of plasma) Due to strong azimuthal flow, the magnetosphere is filled with iogenic ions (sulfur and oxygen). (NASA/JPL) (including orbits of icy satellites)

Plasma flow in the magnetosphere Earth Jupiter Aurora Io

Io plasma torus

Ganymede

Calisto (Credit: John Spencer) (Kivelson 2005) 4 Io plasma torus spectrum (Yoshioka+14, Science)

5 Io plasma torus intensity by Hisaki (for 5 years)

2014 2015 2016 2017 2018

1st season 2nd season 3rd season

Loki Kurdalagon Loki Loki (From IR observation: de Kleer and de Pater, 2016, 2017)

Io plasma torus was quiet during 1st season (Dec. 2013-Apr.2014). Io plasma torus was variable since 2nd season (mainly) due to volcanic activities at Io. 6 HISAKI 2015 Neutral could (Na) Increase in neutral Volcanic activity Neutral could (O) (IR observation) Volcanic contribution to the formation ? Io’s atmosphere + How to escape Plasma torus (S ) the neutral gas ? Neutral cloud ionization Plasma torus (O+) Io plasma torus Inter-change instability (Yoshioka et al. 2014) Plasma torus (S2+) Outer magnetosphere Brightness [Rayleigh] transition energy release temperature incr. (Kimura et al. 2018) Plasma torus (S3+) Activation of aurora How to transport the energy ? Aurora activity How to heat the plasma ? Aurora Plasma heating in Io plasma torus Nov Dec Jan Feb Mar Apr May (Tsuchiya et al. 2018) 2014 2014 2015 2015 2015 2015 2015 7 Plasma parameters during Quiet vs Active period (Volcanically) Yoshioka et al. 2018 Hisaki data Spectrum analysis

Radial distribution of plasma density and temperature

Electron [email protected] : 20%↑ Ion [email protected] : 40%↑ - Mass conservation law - Hot electron cooling via Coulomb interaction

Estimation of neutral source rate & inward and outward timescales (Next slide)

8 In/Out flow (Dependence on the volcanic activity)

Physical-chemistry model [Yoshioka et al, 2018] (dawn+dusk, 65-77nm) Yoshioka et al. 2018 Estimation of neutral source rate & inward and outward timescales 600 400 Increases in inward and outward timescales 2013200 Nov. 2015 Feb. associated with Io’s volcanic eruption IPT power [GW] 0 100 200 300 400 500

Volcanic neutrals 0.8 ton/s_ Volcanic neutrals 3.7 ton/s_

Coulomb coupling Coulomb coupling Charge exchange Charge exchange O S O S

S+ O++ S++ S+ O++ S++

O+ S+++ O+ S+++

34days_ 16hours_ 9.9days_ 9.4hours_ Transport (outward) Hot electron Transport (outward) Hot electron 9 Enhancement of radial plasma circulation

Tsuchiya et al. 2018 - DOY 19-90 : Volcanic eruption at Io & Increased plasma supply (1) Normal state - DOY 25-90 : Enhanced plasma transport from inner to middle magnetosphere - DOY 40-90 : Series of short-lived aurora brightening + plasma torus brightening An analytical model has been developed by Kimura et al. (2018) What is happening between inner and outer M’sphere ? -> JUICE (2) Increase in mass loading (1) (2) (3) (4) (5) Io’s volcano active period 500 Outward transport 400 Plasma torus 300 (4) 200 Transient brightening (5) 68nm 68nm brightness (torus) Io plasma torus plasmaIo 2+ S 0 Transient brightening (aurora) 6 Aurora (3) Global plasma circulation 4 Energy release

Aurora Outward transport 2 (141+/-4nm) 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 Hot electron injection Relative brightness Relative Jupiter polaraurora Jupiter Day of 2015 (1=Jan.1) Aurora 10 intensification Energy transport from outer to inner M’spheres Yoshikawa et al. 2016, 2017, Suzuki et al. 2018

Io plasma torus light curve Pairs of brightening of plasma in (inner magnetosphere) inner magnetosphere and aurorae Brightening of aurora (middle/outer magnetosphere) is earlier than that of the Io plasma torus by ~10 hours. ~12 h Evidence of fast radial transport of energy in the rotation dominant magnetosphere. Aurora light curve

Day of year 2015 Aurora “Pair” of transient brightening of brightening Io plasma aurora and the plasma torus torus (Yoshikawa+2017)

Rapid inward transport Energy release processes 11 (Credit Tomoki Kimura) (~10h) (reconnection) Summary

Volcanic activity (IR observation) • Extreme Ultraviolet (EUV) Volcanic contribution to the atmosphere formation ? spectroscopy is the powerful tool Io’s atmosphere How to escape to study mass and energy flows in the neutral gas ? the Jovian magnetosphere. Neutral cloud ionization • Future Jupiter missions will play Io plasma torus important role to find what is Inter-change instability (Yoshioka et al. 2014) happening in the region between Outer magnetosphere inner and outer magnetosphere. transition energy release (Kimura et al. 2018) • Spatially resolved monitoring Activation of aurora observations of Io is needed to How to transport the energy ? resolve formation of the How to heat the plasma ? Plasma heating in atmosphere and escape from it. Io plasma torus 12