High latitude gas in the Beta Pictoris system. A possible origin related to Falling Evaporating Bodies.

Hervé Beust (1) , Pierre Valiron (1)

1 LAOG - Laboratoire d'Astrophysique de Grenoble

The presence of off-plane Ca II ions in the Beta Pictoris disk, and the non-detection of off-plane Na I atoms, can be explained as a consequence of the evaporation process of Falling Evaporating Bodies (FEBs). In the star-grazing regime, the FEBs are subject to inclination oscillations up to 30 - 40 degrees that causes most metallic species released by sublimation to move off plane The ions are be stopped at about 100 AU from the star. We show that collisions with a neutral medium can stop the ions. The required H I column density is reduced to 10^17 cm^-2, one order of magnitude below present detection limits. We also investigate the possibility that the ions are slowed down magnetically. While the sole action of a magnetic field of the order of 1 microGauss is not effective, the combined effect of magnetic and collisional deceleration processes lead to an additional lowering of the required H I column density.

Mots clés: Stars: circumstellar matter -- Stars individual: \bp -- Methods: analytical; Celestial mechanics; Methods: numerical; Planetary systems; protoplanetary disks; Molecular processes; Magnetic fields

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Hervé Beust, Pierre Valiron. High latitude gas in the Beta Pictoris system. A possible origin related to Falling Evaporating Bodies.. 2007. ⟨hal-00123280⟩