Growing the terrestrial planets from the gradual accumulation of submeter-sized objects
Building the terrestrial planets has been a challenge for planet formation models. In particular, classical theories have been unable to reproduce the small mass of Mars and instead predict that a planet near 1.5 astronomical units (AU) should roughly be the same mass as Earth. Recently, a new model...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 112; no. 46; pp. 14180 - 14185 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
17.11.2015
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | Building the terrestrial planets has been a challenge for planet formation models. In particular, classical theories have been unable to reproduce the small mass of Mars and instead predict that a planet near 1.5 astronomical units (AU) should roughly be the same mass as Earth. Recently, a new model called Viscously Stirred Pebble Accretion (VSPA) has been developed that can explain the formation of the gas giants. This model envisions that the cores of the giant planets formed from 100- to 1,000-km bodies that directly accreted a population of pebbles—submeter-sized objects that slowly grew in the protoplanetary disk. Here we apply this model to the terrestrial planet region and find that it can reproduce the basic structure of the inner solar system, including a small Mars and a low-mass asteroid belt. Our models show that for an initial population of planetesimals with sizes similar to those of the main belt asteroids, VSPA becomes inefficient beyond ∼ 1.5 AU. As a result, Mars’s growth is stunted, and nothing large in the asteroid belt can accumulate. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Edited by Neta A. Bahcall, Princeton University, Princeton, NJ, and approved September 30, 2015 (received for review July 7, 2015) Author contributions: H.F.L. designed research; H.F.L. and K.A.K. performed research; K.J.W. contributed analytic tools; K.A.K., K.J.W., and W.F.B. analyzed data; and H.F.L., K.A.K., and W.F.B. wrote the paper. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1513364112 |