Equation-of-State and Phase-Transition Issues in Models of Ordinary Astrophysical Matter

Outline of program

The need for a precise knowledge of the equation of state for hot dense matter, together with an indication of the location of phase transitions, arises frequently in physics and astrophysics. Good examples in terrestrial physics are the various laboratory experiments carried out under static and dynamical high pressure. Such experiments will be supplemented in the next few years by the planned large-laser-fusion experiments of NIF (Livermore, USA) and Megajoule (Bordeaux, France). All these experiments also serve as sources for plasma diagnostics. Good examples for equation-of-state needs in astrophysics range from studies of the early universe to present-day astrophysical objects such as the Sun, stars, brown and white dwarfs, and planets. The purpose of the proposed workshop is to bring together a group of physicists and astronomers with an interest in this interdisciplinary field.

An important feature of this field is the possibility not only to model astrophysical objects, but to use the models to improve our knowledge of basic physics. In other words, the astrophysical objects become a novel method for plasma diagnostics.

The planned activities of the workshop can be grouped along three lines:

1.    Astrophysics of hot dense plasmas and applications of laboratory diagnostics,

2.    Astrophysics of solid-state objects and links to high-pressure experiments,

3.    Possibly (depending on the final program): Fundamental theory of the equation of state and phase transitions.

Limitations: In defining the scope of the workshop, we deliberately delimit ourselves in two respects:

· We consider only so-called “ordinary matter”, that is, matter, in which electrons and nuclei are separate and defined entities. In other words, we exclude neutron stars (and also quark stars). However, white dwarfs do satisfy our criteria.

· We consider only sufficiently dense plasmas, that is plasmas, which are in thermodynamic equilibrium. The purpose of this restriction is to exclude dilute plasmas such as found in the atmospheres of the Sun and stars, in the solar corona, and in interplanetary and interstellar matter. While these environments of course also fall within plasma physics, they are too diverse for a relatively small and short workshop.

Choice of participants

The number of participants will be equal to or smaller than 30 (plus our minus 2-3). At least 15 places should be open for application by younger people. A group of a similar number of more experienced people will be crucial for the success of the workshop. The organizers have obtained tentative acceptance to participate in the workshop by senior people from USA, Russia, Italy, Denmark, as well as younger people from Macedonia and Bulgaria  (as of middle of May 2003).

Method of work

Several methods of work are anticipated: Senior participants will be expected to give 1-2 longer lectures each. These lectures are expected to be reviews of different topics within the subjects around which the workshop will be organized. Younger participants will present posters about their ongoing research work and briefly introduce them orally. There will be a competition for the most interesting poster, whose author will receive a diploma and an award to purchase equipment (such as software or literature) needed for research. The value of the award will be around 200-250 EUR. The principal goal of this format is to induce fruitful discussions among the participants.

A workshop proposed here could give various results, some of which are broadly formulated in the following:

· Identifying open problems, proposing methods for their solution and pointing directions for future work in the field;

· Establishing contacts among the participants, thus initiating various new, and refreshing existing collaborations;

· Effort will be made to obtain written versions of all the lectures and seminars, so as to open up the possibility of preparing the proceedings of the workshop. Some ideas about the form in which these proceedings could have already exist.

· The organization of such a workshop in the Lorentz Center could also have pedagogical value. The talks of all participants should be held at a level accessible to the students of physics and astronomy in Leiden, for whom the event could become very profitable.