arXiv subjects

A. Lecavelier des Etangs

Publications and source records attributed to A. Lecavelier des Etangs.

166 records · Page 10Linked to original sources

arXiv1998

Dust distribution in radiation pressure outflow. Application to the BD+31d643 disk

The radial distribution of dust has been calculated in outflows driven by radiation pressure in which the gas drag is taken into account. It is shown that the dust distribution in the newly discovered candidate disk around BD+31d643 can be explained by this simple model, provided that the ambient gas of the surrounding cluster IC 348 has a density $ρ\sim 10^4~$cm$^{-3}$. The dust is probably produced within 2300 AU from the central binary star.

astro-ph↗

arXiv1998

Planetary migration and sources of dust in the Beta Pic disk

The dust disk around Beta Pictoris must be produced by collision or by evaporation of orbiting Kuiper belt-like objects. Here we extend the already proposed Orbiting-Evaporating-Bodies (OEB) scenario in which the disk is a gigantic multi-cometary tail supplied by slowly evaporating bodies like Chiron. We show that the number of these OEBs must be several tens of millions, and that this is consistent with the number of bodies needed to explain the presence of CO and CI in the gaseous disk. We explore some possible origin of the required perturbation on the OEBs. If dust is produced by evaporation, a planet with an eccentric orbit can explain the observed asymmetry of the disk, because the periastron distribution of the parent bodies are then expected to be non-axisymmetric. Following Malhotra (1995), we investigate the consequence for the Kuiper belt-like objects of the formation and the migration of an outer planet like Neptune in Fernandez's scheme (Fernandez 1982). We find that bodies trapped in resonance with a migrating planet can significantly evaporate, producing a Beta Pictoris-like disk with similar characteristics like opening angle and asymmetry. We thus show that the Beta Pictoris disk can be a transient phenomenon. The circumstellar disks around main sequence stars can be the signature of the present formation and migration of outer planets.

astro-ph↗

arXiv1995

Dust distribution in disks supplied by small bodies: Is the Beta Pictoris disk a gigantic multi-cometary tail?

We have evaluated the spatial distribution of dust in disks supplied by colliding or evaporating bodies spread in a small belt. The gradient of the distribution of dust expelled by radiation pressure is generally steeper than the one observed around \bp. It follows that, to generate the \bp\ disk distribution in such a way, one should extract relatively more small particles in the production process: thanks to radiation forces, these smaller particles have large eccentricities and thus could be seen at very large distances from their injection place. The evaporation process of comet-like bodies moving slowly inwards may yield the necessary particle size distribution. It is interesting to note that this dynamical description is able to account for the main observational properties of the \bp\ disk, such as the power law distribution with possibly a change in slope, the asymmetry at large distances, and the total mass, all of which have remained unexplained up to now. If confirmed, this scenario may indicate that the \bp\ disk could be looked on as a gigantic multi-cometary tail with its natural constituents: gas and dust.

astro-ph↗

arXiv1994

BETA PICTORIS : Evidence of light variations

We have analyzed Beta Pictoris photometric measurements obtained from La Silla by the Geneva Observatory from 1975 to 1992. These data show evidence of variations in the brightness of the star, with no color dependency. Here, we demonstrate that the light variations are present on long as well as on short time scales. On a long time scale, we show that the apparent magnitude of Beta Pic decreased by 0.011 +/- 0.004 mag from 1979 to 1982. Moreover, when we consider all the measurements, the chance that there is no variation at all can be estimated to be less than 10E-4. On short time scales there is a peculiar feature observed during about 30 days; the variations may be as high as 0.04 magnitude. A maximum entropy reconstruction of the photometric data is tentatively proposed and some physical interpretations are presented.

astro-ph↗