Physics at High Pressures: Interiors of Giant Planets, Extrasolar Planets and Brown Dwarfs
ITP Miniprogram, January 8 - 26, 2001
Coordinators: N. Ashcroft, T. Guillot, R. Jeanloz, & D. Stevenson

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Our intent is to bring together the diverse communities of theorists (planetary, astrophysical and condensed matter physicists) and mix them up with the experimental high pressure people, and observers of brown dwarfs and planets. The special and highly successful character of the ITP mini-programs lies in the opportunity for extended discussions and collaborations of a kind that are seldom possible in a conventional conference or most workshops. This is a area of science that seldom brings together all the interested parties, because they occupy disciplinary niches that are normally disconnected.

Here is a list of the important issues that we would hope can be discussed:

(1) The nature of dense hydrogen, especially under the degenerate but fluid state encountered in these astrophysical bodies. This includes the nature of dense molecular hydrogen, the phase transitions of planetary importance (especially metal-insulator, and the hypothesized "plasma" phase transition, but also solid-liquid, and others that might influence the thermodynamics or transport properties such as electrical conductivity significantly). Theoretical work, including simulations, experimental work (static compression, shock waves, laser compression) and inferences from observation are all involved.

(2) The nature of other light elements and compounds under relevant conditions, including their mixtures with hydrogen. This includes oxygen (normally as water) carbon (normally as methane but also with other H/C ratios, including zero [i.e., diamond] ) , ammonia, the noble gases, and the behavior of rock forming elements (e.g. silicon, iron, magnesium), especially in the presence of high density hydrogen. As planets that could be Uranus-like are now close to detection or being detected, it is appropriate to include these bodies and their dominant constituents in the range of consideration.

(3) The relationship between the expected properties of these bodies and their observed behavior : Brown dwarf radii, cooling times, atmospheric composition, magnetic fields, possible seismological activity, etc. This involves the equation of state theorists, the astrophysical theorists and the observers. We would expect to include the most up-to-date report on planet detection programs, as this field is so rapidly developing. However, we would also wish to involve observers whose techniques are (or might become) more diagnostic of the state of these bodies, rather than merely indicators of their presence. This includes information from transits or direct detection, determination of spin, magnetic field (radio wave emission), possible coronal emission (because it tells us about the internal dynamics) , etc. It also includes solar system observations that are or could be diagnostic of interior properties of our giant planets: Higher order gravity, heat flow interpretations, magnetic field behavior (including dynamo theory), nature of deep-seated zonal flows, prevalence of convection as a heat transport mechanism, possible normal mode detection and the interrelationships of these observations.

(4) We would also wish to involve those who work on the formation of these bodies, or make observations pertaining to this, since this often influences the evolutionary path that these bodies take (e.g. the entropy of the deep interior, degree of mixing of constituents and so forth, consequences of large orbital migration, tidal stability). This includes the consequences of large impacts during or after planet formation (e.g. collisions of Earth mass bodies with Jupiter mass bodies). note, however, that this is not a primarily a workshop on formation of planets.

We are open to suggestion about others who might be included, especially where new observational (e.g., seismological) or experimental techniques might be involved.

An important aspect of an ITP mini-program is the presence of a strong core of three week participants. We understand that experimentalists and observers may find it difficult to schedule attendance for more than one week. We thus hope that they will be able to join us at least part of the three-week period. Among theorists, short stays will be considered, but preference will be given to those able to remain at Santa Barbara during the entire three-week period. We have a budget to help defray the expenses of participants in the program.

Please apply as soon as possible. We intend to begin inviting participants in August and early September.

Last modified: July 28, 2000 ds