Exoplanets & Exomoons

Rocky Planet Formation: Quick and Neat

By Keith Cowing
Press Release
August 22, 2016
Filed under
Rocky Planet Formation: Quick and Neat

We reconsider the commonly held assumption that warm debris disks are tracers of terrestrial planet formation. The high occurrence rate inferred for Earth-mass planets around mature solar-type stars based on exoplanet surveys (roughly 20%) stands in stark contrast to the low incidence rate (less than 2-3%) of warm dusty debris around solar-type stars during the expected epoch of terrestrial planet assembly (roughly 10 Myr).

If Earth-mass planets at AU distances are a common outcome of the planet formation process, this discrepancy suggests that rocky planet formation occurs more quickly and/or is much neater than traditionally believed, leaving behind little in the way of a dust signature. Alternatively, the incidence rate of terrestrial planets has been overestimated or some previously unrecognized physical mechanism removes warm dust efficiently from the terrestrial planet region. A promising removal mechanism is gas drag in a residual gaseous disk with a surface density of roughly or somewhat more than 0.001% of the minimum mass solar nebula.

Scott J. Kenyon, Joan R. Najita, Benjamin C. Bromley
(Submitted on 18 Aug 2016)

Comments: 34 pages of text, 8 figures, ApJ, in press
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:1608.05410 [astro-ph.EP] (or arXiv:1608.05410v1 [astro-ph.EP] for this version)
Submission history
From: Scott J. Kenyon
[v1] Thu, 18 Aug 2016 20:00:00 GMT (318kb,D)

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