Issue |
A&A
Volume 388, Number 2, June III 2002
|
|
---|---|---|
Page(s) | 615 - 631 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20020490 | |
Published online | 31 May 2002 |
Global
modes and migration of
protoplanetary cores in eccentric protoplanetary discs
Astronomy Unit, Queen Mary, University of London, Mile End Rd, London E1 4NS, UK
Corresponding author: jcbp@maths.qmw.ac.uk
Received:
29
November
2001
Accepted:
28
March
2002
We calculate
global modes with low
pattern speed corresponding
to introducing a finite eccentricity into a protoplanetary disc.
We consider disc models which are either isolated
or contain one or two
protoplanets orbiting in an inner cavity.
Global modes
that are strongly coupled to inner protoplanets
are found to
have disc orbits which tend to have apsidal lines
antialigned with respect to those of the inner protoplanets.
Other modes corresponding to free disc modes may be global
over a large range of length scales and accordingly be long lived.
We consider the
motion of a protoplanet in the earth mass range
embedded in an eccentric disc
and determine
the equilibrium orbits which maintain fixed
apsidal alignment with respect to the disc gas orbits.
Equilibrium eccentricities are found
to be comparable or possibly exceed
the disc eccentricity.
We then approximately calculate the tidal interaction with the disc
in order to estimate
the orbital migration rate. Results are found to deviate
from the case of axisymmetric disc with near circular protoplanet
orbit once eccentricities of protoplanet and disc orbits
become comparable to the disc aspect ratio in magnitude.
Aligned protoplanet orbits with very similar
eccentricity to that of the gas disc are found to
undergo litle eccentricity change
while undergoing inward migration in general.
However, for significantly larger orbital
eccentricities,
migration
may be significantly reduced or even reverse from inwards to outwards.
Thus the existence of global non circular motions
in discs with radial excursions comparable to the semi-thickness
may have important consequences for the migration and survival
of protoplanetary cores in the earth mass range.
Key words: planetary systems: formation / planetary systems / planetary systems: protoplanetary disks / stars: individual: Ups And
© ESO, 2002
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