Comets and Asteroids

Exocomets Size Distribution In The β Pictoris Planetary System

By Keith Cowing
April 29, 2022
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Exocomets Size Distribution In The β Pictoris Planetary System
Plot of the cumulative size distribution of the exocomets in β Pic. The cumulative size distribution is plotted with blue squares for each exocomet and the corresponding fit excluding the largest comet is plotted with the red thick line. For comparison, published size distributions measured in the Solar system are plotted with thin dashed lines for asteroids in comets orbits (ACO), on near Earth orbits (NEO) and non-near Earth orbits (non-NEO) (A06, ref.30), Jupiter family comets (JFC) (T06, ref.25 ; S11, ref.26 ; F13, ref.28 ; B17, ref.29), and long-period comets (LPC) (B17, ref.29 ; B19, ref.24). In this plot, the size distributions for the objects in the Solar system have been scaled to have a cumulative number of about 10 objects with radius above 2 kilometers. The radii of the β Pic comets have been estimated using the derivation described in the Method section. The conclusion on the similarity of the size distributions in β Pic and the Solar system is independent of these estimates.

The star β Pictoris harbors a young planetary system, which is characterized by the presence of a gaseous and dusty debris disk, at least two massive planets and many minor bodies. For more than thirty years, exocomets transiting the star have been detected using spectroscopy, probing the gaseous part of the cometary comas and tails.

The detection of the dusty component of the tails can be performed through photometric observations of the transits. Since 2018, the Transiting Exoplanet Survey Satellite has observed β Pic for a total of 156 days. Here we report an analysis of the TESS photometric data set with the identification of a total of 30 transits of exocomets.

Our statistical analysis shows that the number of transiting exocomet events (N) as a function of the absorption depth (AD) in the light curve follows a power law in the form dN(AD)∝AD−α, where α=2.3±0.4. This distribution of absorption depth leads to a differential comet size distribution proportional to R−γ, where γ=3.6±0.8, showing a striking similarity to the size distribution of comets in the Solar system and the distribution of a collisionally relaxed population (γD=3.5).

A. Lecavelier des Etangs, L. Cros, G. Hébrard, E. Martioli, M. Duquesnoy, M. A. Kenworthy, F. Kiefer, S. Lacour, A.-M. Lagrange, N. Meunier, A. Vidal-Madjar

Comments: This is a preprint version of an article published in Scientific Reports. The final version is available online at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2204.13618 [astro-ph.EP] (or arXiv:2204.13618v1 [astro-ph.EP] for this version)
Journal reference: Scientific Reports 12, 5855 (2022)
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Submission history
From: Alain Lecavelier des Etangs
[v1] Thu, 28 Apr 2022 16:31:28 UTC (1,276 KB)

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