Issue |
A&A
Volume 372, Number 2, June III 2001
|
|
---|---|---|
Page(s) | 616 - 626 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20010528 | |
Published online | 15 June 2001 |
The physico-chemical history of Falling Evaporating Bodies around β Pictoris: investigating the presence of volatiles
1
Laboratoire d'Astrophysique de l'Observatoire de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble Cedex 9, France
2
Laboratoire de Planetologie de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble Cedex 9, France
Corresponding author: C. Karmann, ckarmann@obs.ujf-grenoble.fr
Received:
22
December
2000
Accepted:
12
March
2001
Transient spectral absorption events have been monitored for
many years toward the star β Pictoris and have been interpreted as
resulting from the transit across the line of sight of evaporating
comet-sized bodies (Falling Evaporating Bodies, or FEBs). The
model shows that these bodies come from circular orbits at AU, becoming star-grazers due to planetary perturbations. The
physics of the evaporation of those bodies is widely influenced by
their physico-chemical properties, especially the presence of
volatile matter. We investigate here this question from a modeling
point of view, adapting for that case the models designed for solar
comets. We simulate the physico-chemical evolution of the FEB
progenitors on circular orbits for a time comparable to the supposed
age of βPic, and constrain the quantity of volatiles present in them
in relationship with its age and to the semi-major axis of the
orbits. We also constrain this semi-major axis by investigating its
influence on the dynamical model of FEB generation by planetary
perturbations, and show that it is probably less than ~10 AU.
Finally, we show that demanding the FEB progenitors to be icy in a
major part of their volume at those distances is probably an
unrealistic constraint, and that they more likely look like
asteroids with perhaps a small icy nucleus rather than fully icy
comets. This result leads to a revision of the FEB evaporation
model that has been assumed up to now.
Key words: stars: βPic / methods: numerical / comets: general / stars: circumstellar matter / planetary systems: formation
© ESO, 2001
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