QUOTE (Marz @ Oct 19 2005, 10:13 AM)
In 2011, ALMA should be getting first light in Chili. One of its objectives is to "detect signatures from planets as they form and stars as they collapse and condense from an accretion of gas." So this should resolve alot of speculation about how solar systems form around different star types.
From what I've read, the planets themselves are more likely to result in ejecting each other during early solar system formation than having another star interact. Jupiter-class planets tend to act is gatekeepers; stablilizing the orbits of the other planets, and presumably correcting any perturbations from passing stars.
So therefore, maybe the Kuiper objects themselves are occassionally passing close enough to each other to act as their own nemisii (nemisises? nemisae?).
Paper: astro-ph/0510527
Date: Tue, 18 Oct 2005 18:11:26 GMT (91kb)
Title: Dust Dynamics and Surface Brightness Profiles of Debris Disks: The Case
of AU Mic
Authors: Linda E. Strubbe and Eugene I. Chiang
Comments: Submitted to ApJ
\\
AU Microscopii is a 12-Myr-old M dwarf that harbors an optically thin disk of
dust. Within a projected distance b from the star of 43 AU--in the "inner
disk"--the scattered-light surface brightness falls as b^-g, where g = 1-2. In
the "outer disk," the brightness drops more steeply, with g = 4-5. We devise a
theory to explain the entire profile, including the break. Our theory asserts
that the AU Mic disk is in steady state and makes no recourse either to
unequilibrated cataclysms or to preserved primordial conditions. We posit a
ring of parent bodies on circular orbits near 43 AU: the "birth circle." At the
birth circle, grains are produced by colliding parent bodies. Grains are
removed by the star's wind and radiation, and by destructive grain-grain
collisions. Grains having sizes just large enough to remain bound to the star
occupy highly eccentric orbits and dominate scattering of starlight in the
outer disk. We prove that for large stellocentric radius r, their surface
density S scales as r^-5/2. Eccentricities and semi-major axes of all grains
decay by corpuscular and Poynting-Robertson (CPR) drag. Grains that migrate
inside the birth circle by CPR drag dominate scattering in the inner disk;
there, S scales as r^0, with modifications introduced by collisions. We predict
the outer disk to be bluer than the inner; the color gradient is sensitive to
the stellar mass-loss rate M-dot. Over the system age, the birth circle sheds
order unity of its mass, 0.6 [M-dot/(100 M-dot-sun)] lunar masses, in bodies of
size 2 [M-dot/(100 M-dot-sun)] cm. The birth circle of AU Mic resembles the
Solar System's Kuiper belt. That planetary systems have sharp outer edges
suggests planetesimal formation requires disk properties to meet threshold
conditions.
\\ (
http://arXiv.org/abs/astro-ph/0510527 , 91kb)