SPAT0028-2 : Planetary magnetospheres and aurorae

University of Liege | Version française

Academic year 2014-2015

Value date : 12/05/2015

SPAT0028-2

Planetary magnetospheres and aurorae

Duration :

20h Th, 10h Pr

Number of credits :

Master in Space Sciences, Research focus, 1st year		3

Master in Space Sciences, Research focus, 2nd year		3

Lecturer :

Denis Grodent

Language(s) of instruction :

French language

Organisation and examination :

Teaching in the second semester

Course contents :

Polar aurorae do not only exist on Earth. They also appear on other planets and other objects in our Solar System and even in other planetary systems. These phantom-like displays are the most impressive evidence of permanent interaction between the planets and their spatial environment. In most cases, this interaction results from the combination of the Sun-Magnetosphere-Ionosphere. Other combinations exist and are just as effective at producing aurorae. We will explore the Solar System looking for such combinations.

Learning outcomes of the course :

Preliminary plan 1. Magnetospheres Two components are necessary to create a magnetosphere: a magnetic field and a plasma flow. 1.1 Magnetic field Three types of planetary magnetic fields will be considered: intrinsic, inferred and residual. We will explain the origins of these fields (notably the dynamo effect) for different objects in the Solar System. 1.2 Plasma flow 1.2.1. The most obvious is the solar wind. We describe the origin of this solar plasma and its characteristics (interplanetary magnetic field, the frozen field principle, solar activity in terms of cycles, CME, CIR, ...) 1.2.2. We will also consider local plasma flows, such as the Io plasma torus around Jupiter and we will describe the origins of magnetospheric plasma. 1.3. Movements of charged particles in a planetary electromagnetic field. We will reintroduce the concept of Maxwell equations and magnetohydrodynamics which will allow us to explain the movement of particles which are trapped in the planetary magnetic field. We will also introduce the important concept of magnetic reconnection. 1.4. Properties of magnetospheres Magnetospheres all have more or less the same structure. We will therefore define concepts such as magnetopause, magnetosheath, plasmasphere, magnetodisc, as well as the different electric currents which circulate in these areas. 1.5. Detailed description and comparison between the magnetospheres of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, comets, pulsars, including their commonalities and their differences. 2. Combination of Sun-Magnetosphere-Ionosphere(SMI) 2.1. Planetary atmospheres and ionospheres Primarily Earth, Jupiter and Saturn. 2.2. S-M combination Dungey Cycle, magnetrospheric convection, reconnections. 2.3. M-I combination 2.3.1. Aligned currents 2.3.2. Vasyliunas Cycle, co-rotation, Hill processes 2.3.3. Interaction between satellites, Io, Ganymede, Europe, Tital, Encelade, ... 2.4 S-M-I combination 2.4.1. Magnetospheric cycles, internal and external checks on magnetosphere dynamics. 2.4.2. Storms and magnetic sub-storms, creation of plasma bubbles 3. Polar aurorae 3.1. Particle-atmosphere interactions 3.1.1. Approximation using two beams, CSDA method, ... 3.1.2. Auroral photochemistry 3.1.3. Auroral heating 3.2. Observing aurorae 3.2.1. Elements of spectroscopy 3.2.2. Auroral emissions in radio, IR, visible, UV and RX fields. 3.2.3. Relationship between colour and atmospheric survey 3.2.4. Observations from the Earth: VLT, IRTF, Nançay radiotelescope, ... 3.2.5. Observations from space: HST, IMAGE, XMM, CXO, ... 3.2.6. Observations in situ: Voyager, Ulysses, Gallileo, Cassini, Vex, Mex, JUNO 4. Future prospects and new space missions Our laboratory is involved in a series of space projects such as JUNO and EJSM ... We use them to illustrate prospective studies in this field.

Prerequisites and co-requisites/ Recommended optional programme components :

Co-ordination will be required to ensure that the contents of this course are aligned with the course on "L'environnement magnétique terrestre" and the compulsory courses "Atmosphères terrestre et planétaire" and "Physique des plasmas". This course relies principally on the knowledge acquired in the field within LPAP.

Planned learning activities and teaching methods :

1. Problems and practical work A personal or team work will be requested. It will be presented individually during the final examination. Several activities are possible. They mainly rest on the Planeterrella experiment and the observation of Jupiter's radio auroral emissions.

Mode of delivery (face-to-face ; distance-learning) :