Solar Wind Vs. Internal Processes

Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes

N. Krupp and the Europlanet N2 Discipline working group on Magnetospheres, Exospheres, Ionospheres

special thanks to Fran Bagenal and Emma Bunce

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Jupiter’s magnetosphere

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Jupiter Different types of aurora

Polar Aurora

e k a w

Secondary Oval o Main Oval I

Io footprint Hubble Space Telescope Clarke et al.

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes

Cowley et al. 2003

Dawn Dusk

Side View

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Equatorial View Dawn Dusk Polar View Hill Region Sub- corotating Dawn Dusk plasmasheet

Main Auroral Oval

Side View

Outer Magnetosphere “Cushion Region”

Side View

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes ? ? ? Equatorial View Dawn Dusk Polar View

Dawn Dusk How important is the Dungey Cycle?

How Much of ?? ?? ?? Polar Flux is Open? Side View

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Large-scale current system in the Jovian magnetosphere

After Hill (1979) and Vasyliunas (1983)

• Discovery of a local time asymmetry in the system of azimuthal currents which distend the field lines away from the planet (Bunce and Cowley, 2001a; Khurana, 2001) • Investigations of field-aligned currents associated with magnetosphere-ionosphere coupling currents found to be ~1μAm-2 (Bunce and Cowley, 2001b; Khurana, 2001)

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Origin of the Jovian main aurora Calculated upward field-aligned current profile

• Bunce and Cowley (2001b), Cowley and Bunce (2001), Hill (2001) and Southwood and Kivelson (2001) suggest the main auroral oval is due to the breakdown of corotation of the equatorial plasma • Modulation of the oval in anti-correlation with solar wind dynamic pressure (C&B, 2001, 2003a&b; S&K, 2001)

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Galileo observations

¾ Most prominent and well defined boundary Æ change in the electron pitch angle distributions located between 10

and 17 RJ. Ions

Dawn Dusk 180°

90° Electrons 0° 40RJ 20RJ 10RJ 20RJ 40RJ

Inner Region Outer Region Pancake distribution Field aligned with electrons Mag. Field maximum at 900 bi-directional electrons

Tomás et al., 2004a 40RJ c.a. 40RJ EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Tracing the magnetic field lines ¾ Comparing the footprints of the PAD boundary (VIP4 model) with the HST observations

North Pole South Pole 00 1800

2700 900 2700 900

1800 00 HST observations

* Io ∆ PAD boundaries

* Secondary Oval Footprints 6 and 25 RJ (VIP4) * Main Oval

¾ Good conjugation between the PAD boundary and the secondary oval

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes The Precipitation energy flux

¾Considering: ¾The precipitation energy flux given by : m. a. o. Emax ε ⋅= j(E,E γ ⋅dE) ∫ E Emin 1 Sec. Oval ¾ Measured electron’s spectra at the PAD 140 kR boundary.

¾ Strong pitch-angle scattering. 65 kR

Mean Brightness (kR) Brightness Mean E2 ¾ Electron’s energy : E1 Є [55, 304] keV. Pole Equator E2 Є [55, 188] keV. Courtesy of D. Grodent, Univ. Liège

¾ Sufficient to directly produce the observed auroral emissions of the secondary oval without the need of a field aligned potential drop.

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Dynamics in Jupiter’s magnetosphere Energetic Particle Injections & correlation to auroral emissions

24 hour Galileo Energetic Particle Spectrogram HST Image of Jupiter’s UV aurora

Mauk et al., 1997; 1999, 2000

Extreme “storm-time” dynamics Auroral manifestation of observed in the vicinity of near-Europa storm Europa’s orbit dynamics

16 days

V 1 3 days

0 t

2 0

iso

- 5

An -1 6

-2 radial azimuthal 10 Ion anisotropy flow anisotropy Ion 5

south-north -5

Magnetic field [nT]

-10 96266 96 268 96270 96272 96274 96276 96278 96280 91.31 96.76 101.33 105.08 108.06 110.32 111.87 112.74 02:05 02:15 02:25 02:34 02:43 02:51 02:58 03:06 UT, JSE [R ], Loc. Time r Jup South-north magneticfield

Location: 90-113 Rj

Krupp et al, 2004

More X outward Transient periodical disturbances - l in bursts Jupiter e with repetition period of several days Sun More inward bursts (the most characteristic 2-3 days) are observed in the Jovian magnetotail! ?

M ? ag ne top au se

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Jupiter Aurora and tail disruptive events (Grodent et al., 2004) In Situ* Auroral Spots Russell et al., Woch et al., Krupp et al. Distance 70-120 Rj >100 Rj

Local Time postmidnight premidnight

Size ~25 Rj 5-50 Rj

Duration Mins-hours 5 min-1hour

Recurrence 4 hours-3days 1-2 days

25 Rj

2 Rj

~8000 Rj x 0.01 ions/cc = 500 tons per plasmoid

1 per day = 0.006 ton/s 1 per hour = 0.15 ton/s

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Saturn’s aurora Saturn’s magnetosphere is also believed to be corotation-dominated, like Jupiter’s It also has an auroral oval as shown in the HST-STIS images below Is this also due to corotation-enforcement currents?

Saturn aurora (HST–STIS) Taken from Cowley et al. (2003)

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Field-aligned current density in the northern ionosphere calculated from the divergence of the horizontal current - effect of the large-scale flow variation Taken from Cowley and Bunce, 2003

Voyager-2 Voyager-1

12 ⎛ W ⎞ ⎜ th ⎟ −2 The limiting current is j|| i0 = eN ≈ 70 nA m ⎝ 2π me ⎠

Cowley, Bunce and Prangé, 2004

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes

DAWN DUSK

model estimates are in good agreement with HST-STIS images of Saturn’s auroral oval

Image taken from Cowley et al., 2004 EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Electron beams Dawn

Sun

• FUV auroral images from HST STIS instrument (Gérard et al., JGR 209, 207, 2004) [no observations of the aurora during the electron beam events] • ~80 deg latitude feature corresponds to just inside m’pause; others are from much deeper in the magnetosphere. • Periods of electron counterstreaming map into auroral zone. Beams map well in a statistical sense into the regions of Saturn’s aurora.

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Outer magnetosphere dynamics: aurora and radio emissions show rotational modulation + solar wind control

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al. Planetary aurorae and their electrodynamic drivers; solar wind vs. internal processes Europlanet N2 DWG 2 Science Case 1 1 - Objective or science goal: Solar wind interaction at Jupiter and Saturn including aurorae? 2 - Needed data sets: Millennium Campaign at Jupiter (Cassini, Galileo, Hubble Space telescope (UV), Chandra X-ray Observatory, X-ray Multi-Mirror, InfraRed Telescope Facility), other ground-based observations Saturn Hubble campaign 2004 and 2007 3 - Problem description Modelling of the Solar wind-magnetosphere-ionosphere coupling e.g. reconnection rates, cusp processes and compare it with existing data sets. Variations of particle fluxes, pitch angle distributions, energy spectra, aurora brightness,... as indicators of solar wind influence. 4 - Current solution: the way scientist presently work to select data of interest, to access these data and to process it. PDS, MAPS KP, direct contact between scientists 5 - What services users expect from an IDIS to work more efficiently add new data sets (relevant events on the Sun, additional data sets from missions in Earth orbit and in the heliosphere for a given time period), add new global transport and plasma models, add relevant Laboratory measurements 6 - Other comments 7 - Key references on science and methodology for this science case Cowley and Bunce, Clarke et al., Crary et al, Hansen et al., Tomas et al.,... experience from Earth magnetosphere,...

EPSC2006-A-00395 EPSC, September 19, 2006, Berlin, Germany Norbert Krupp et al.