SETI bioastro: Long-Term Collisional Evolution of Debris Disks

• Previous message: LARRY KLAES: "SETI bioastro: Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telesc"

Long-Term Collisional Evolution of Debris Disks

Authors: Torsten Löhne, Alexander V. Krivov, Jens Rodmann

(Submitted on 23 Oct 2007)

Abstract: We simulated the long-term collisional depletion of debris disks
around solar-type (G2V) stars with our code. The numerical results were
supplemented by, and interpreted through, a new analytic model. A few
general scaling rules for the disk evolution are suggested. The timescale of
the collisional evolution is inversely proportional to the initial disk mass
and scales with radial distance as r^4.3 and with eccentricities of
planetesimals as e^2.3. Further, we show that at actual ages of debris disks
between 10 Myr and 10 Gyr, the decay of the dust mass and the total disk
mass follow different laws. The reason is that the collisional lifetime of
planetesimals is size-dependent. At any moment, there exists a transitional
size, which separates larger objects that still have the “primordial” size
distribution set in the growth phase from small objects whose size
distribution is already set by disruptive collisions. The dust mass and its
decay rate evolve as that transition affects objects of ever-larger sizes.
Under standard assumptions, the dust mass, fractional luminosity, and
thermal fluxes all decrease as t^xi with xi = -0.3…-0.4. Specific decay laws
of the total disk mass and the dust mass, including the value of xi, largely
depend on a few model parameters, such as the critical fragmentation energy
as a function of size, the primordial size distribution of largest
planetesimals, as well as the characteristic eccentricity and inclination of
their orbits. With standard material prescriptions and a distribution of
disk masses and extents, a synthetic population of disks generated with our
analytic model agrees quite well with the observed Spitzer/MIPS statistics
of 24 and 70 micron fluxes and colors versus age.

Comments: 16 pages, 15 figures, accepted for publication in ApJ (23 Oct
2007), abstract shortened

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0710.4294v1 [astro-ph]

Submission history

From: Torsten L\”ohne [view email]

[v1] Tue, 23 Oct 2007 19:00:26 GMT (141kb)

http://arxiv.org/abs/0710.4294

• Previous message: LARRY KLAES: "SETI bioastro: Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telesc"

This archive was generated by hypermail 2.1.6 : Wed Oct 24 2007 - 12:04:46 PDT