Vega’s hot dust from icy planetesimals scattered inward by an outward-migrating planetary system

Sean N. Raymond, Amy Bonsor

(Submitted on 26 Mar 2014)

Vega has been shown to host multiple dust populations, including both hot exo-zodiacal dust at sub-AU radii and a cold debris disk extending beyond 100 AU. We use dynamical simulations to show how Vega’s hot dust can be created by long-range gravitational scattering of planetesimals from its cold outer regions. Planetesimals are scattered progressively inward by a system of 5-7 planets from 30-60 AU to very close-in. In successful simulations the outermost planets are typically Neptune-mass.

The back-reaction of planetesimal scattering causes these planets to migrate outward and continually interact with fresh planetesimals, replenishing the source of scattered bodies. The most favorable cases for producing Vega’s exo-zodi have negative radial mass gradients, with sub-Saturn- to Jupiter-mass inner planets at 5-10 AU and outer planets of 2.5 to 20 Earth masses.

The mechanism fails if a Jupiter-sized planet exists beyond ~15 AU because the planet preferentially ejects planetesimals before they can reach the inner system. Direct-imaging planet searches can therefore directly test this mechanism.

Comments:Accepted to MNRAS Letters. 5 pages, 4 figures

Subjects:Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Cite as: arXiv:1403.6821 [astro-ph.EP]

 (or arXiv:1403.6821v1 [astro-ph.EP] for this version)

Submission history

From: Sean Raymond 

[v1] Wed, 26 Mar 2014 19:59:58 GMT (156kb)

X