36th DPS Meeting, 8-12 November 2004
Session 35 Extrasolar Planets
Poster II, Thursday, November 11, 2004, 4:15-7:00pm, Exhibition Hall 1A

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[35.05] Dust dynamics as a way to contraint the gas density in the Beta-Pictoris disc

P. Thebault (Observatoire de Paris), J.-C. Augereau (Leiden Observatory)

The amount of gas in the Beta-Pictoris system is still poorly constrained. The Thi et al.(2001) estimate of at least 50 Earth masses of H2 was later contradicted by FUSE observations setting an upper limit 3 orders of magnitude smaller for the H2 column density. However, Brandeker et al.(2004) noticed that various beta>1 ions (Ca, Fe,..) were surprisingly observed on bound keplerian orbits and argued that a large amount of Hydrogen (40 Earth masses) could act as a ``braking agent" preventing them from being blown out.

We investigate this problem by looking at the effect of gaseous friction on the dust dynamics and use this as a tool to derive constraints on the gas density and its radial distribution. We perform simulations of the evolution of a dust population, continuously produced by parent bodies, embedded in a gaseous medium. We explore different parent bodies distributions and dust size distributions as well as different gas density profiles. We then derive the corresponding scattered light mid-plane profiles for the dust and compare them to observational data. Preliminar results indicate that large amount of gas in the region beyond 100 AU always lead to dust distributions contradicting observational profiles. In this case, high gas densities might be ruled out and an alternative explanation for the puzzling observations of beta>1 ions on keplerian orbits should be found.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.