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Brown Dwarfs and Extrasolar Planets

Periodic Report Summary - BROWN DWARF (Brown dwarfs and extrasolar planets)

2.1 Summary description of the project objectives:

The main project objectives are the following: observations of brown dwarfs and extrasolar planets; analysis of the data; constraints on the planet properties; theory, and nature of the variability of brown dwarfs; theoretical modelling of extrasolar planets; development of the code Shellspec.

2.2 A description of the work performed since the beginning of the project

The researcher has been working on several topics in the field of extrasolar planets and brown dwarfs and in both observations and theory. Several applications for the observing time on the Kuiper, MMT, ESO 2.2 m, ESO 3.6 m, Rozhen 2 m telescope have been prepared and submitted. Observations with the Kuiper telescope were performed. At the same time we developed and started a project to observe exoplanet transits in Slovakia. Planetary transits in two systems, namely WASP-10 and Corot-Exo-2 were observed. Variability of brown dwarfs and low mass stars is being studied.

Study of the planet-star interaction and a search for new planets orbiting massive stars are in preparation. In the theory and modelling the researcher studied the day-night side cooling of the irradiated planet and was developing his code Shellspec so that it can be used to model the light curves and spectra of extrasolar planets.

A significant amount of effort was devoted to the education and training of a new generation of students and researchers in this new field of research in Slovakia and neighbouring countries as well as public relations.

2.3 Description of the main results achieved so far

The funding of this grant resulted in a progress in several fronts in the field of brown dwarfs and extrasolar planets. For the first time the cooling of an irradiated planet is studied from both its day and night sides. It is argued that the both sides can cool at a different rate. The researcher has been working on his code Shellspec (designed originally for interacting binaries) so that it can be applied to extrasolar planets. The mutual irradiation of the bodies and day-night heat redistribution was incorporated into the model so far. The observations require that a significant heat redistribution between the day and the night side of the planet is in operation. Study of the planetary transits resulted in putting additional constraints on planet parameters and presence of another planets in two systems: WASP-10 and Corot-Exo-2.

Variability of brown dwarfs and low mass stars is being studied. Preliminary results indicate that contrary to the previous reports on a sudden drop in brightness in a few objects our observations do not exhibit such kind of behaviour. Consequently, an idea of eclipses is not very likely.

Lectures and teaching: the researcher elaborated and gave first ever graduate course in the country on brown dwarfs and extrasolar planets (Commenius University, Bratislava, Slovakia) and another similar course (University of Pavel Jozef Safarik, Kosice, Slovakia) is in preparation. Supervision of one graduate student from the Czech Republic and one postdoc from Ukraine.

Publications: six publications, more in preparation.

Expected final results and their potential impact and use:

The Shellspec code will be developed and improved further so that is can be used to model and study the spectra and light curves of extrasolar planets and brown dwarfs. It will be made public on the website: http://www.ta3.sk/~budaj/shellspec.

Observations of extrasolar planets will provide improved radii and orbital elements of the planets which will be used to put constraints on the theory, physics of their interior and chemical composition. More light will be shed on the variability of some young brown dwarfs.

The researcher will further develop a graduate course on extrasolar planets and brown dwarfs at two universities which will educate and train first students in the Slovak Republic. Researcher will also train graduate students from the Czech Republic and postdocs from Ukraine in this new field of research.

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