From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Mar 15 2007 - 14:10:15 PDT
Astrophysics, abstract
astro-ph/0703237
From: Taro Matsuo [view email]
Date: Sat, 10 Mar 2007 04:48:31 GMT (616kb)
Planetary Formation Scenarios Revistied: Core-Accretion Versus Disk
Instability
Authors: T. Matsuo, H. Shibai, T. Ootsubo (Nagoya University), M. Tamura
(NAOJ)
Comments: accepted for publication in The Astrophysical Journal
The core-accretion and disk instability models have so far been used to
explain planetary formation. These models have different conditions, such as
planet mass, disk mass, and metallicity for formation of gas giants. The
core-accretion model has a metallicity condition ([Fe/H] > −1.17 in
the case of G-type stars), and the mass of planets formed is less than 6
times that of the Jupiter mass MJ. On the other hand, the disk instability
model does not have the metallicity condition, but requires the disk to be
15 times more massive compared to the minimum mass solar nebulae model. The
mass of planets formed is more than 2MJ. These results are compared to the
161 detected planets for each spectral type of the central stars. The
results show that 90% of the detected planets are consistent with the
core-accretion model regardless of the spectral type. The remaining 10% are
not in the region explained by the core-accretion model, but are explained
by the disk instability model. We derived the metallicity dependence of the
formation probability of gas giants for the core-accretion model. Comparing
the result with the observed fraction having gas giants, they are found to
be consistent. On the other hand, the observation cannot be explained by the
disk instability model, because the condition for gas giant formation is
independent of the metallicity. Consequently, most of planets detected so
far are thought to have been formed by the core-accretion process, and the
rest by the disk instability process.
http://arxiv.org/abs/astro-ph/0703237
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