SETI bioastro: Meteoritical and dynamical constraints on the growth mechanisms and formation ti

From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Jul 17 2006 - 08:40:50 PDT

  • Next message: LARRY KLAES: "SETI bioastro: Detection of Giant Radio Pulses from the Pulsar PSR B0656+14"

    Astrophysics, abstract
    astro-ph/0607317

    From: Edward Scott [view email]

    Date: Thu, 13 Jul 2006 23:11:41 GMT (858kb)

    Meteoritical and dynamical constraints on the growth mechanisms and
    formation times of asteroids and Jupiter

    Authors: Edward R. D. Scott

    Comments: Accepted for publication in Icarus

    Peak temperatures inside meteorite parent bodies are closely linked to
    accretion times. Most iron meteorites come from bodies that accreted <0.5
    Myr after CAIs formed and were melted by 26Al and 60Fe, probably inside 2
    AU. Chondrite groups accreted intermittently over 4 Myr starting 1 Myr after
    CAIs formed when planetary embryos may already have formed at ~1 AU.
    Meteorite evidence precludes accretion of late-forming chondrites on the
    surface of early-formed bodies; instead chondritic and non-chondritic
    meteorites probably formed in separate planetesimals. Maximum metamorphic
    temperatures in chondrite groups correlate inversely with mean chondrule
    age, as expected for 26Al heating. Dynamical models suggest that asteroids
    accreted before Jupiter. Therefore Jupiter probably reached its current mass
    >3-5 Myr after CAIs formed. This precludes formation of Jupiter via a
    gravitational instability <1 Myr after the solar nebula formed, and strongly
    favors core accretion. Shocks formed by gravitational instabilities in the
    disk, proto-Jupiter, or by planetary embryos may have produced some
    chondrules. The minimum lifetime for the solar nebula of 3-5 Myr inferred
    from CAI and chondrule ages may exceed the median 3 Myr lifetime for
    protoplanetary disks, but is well within the total 1-10 Myr range. Shorter
    formation times for extrasolar planets may help to explain why their orbits
    are unlike those of solar giant planets.

    http://arxiv.org/abs/astro-ph/0607317


  • Next message: LARRY KLAES: "SETI bioastro: Detection of Giant Radio Pulses from the Pulsar PSR B0656+14"

    This archive was generated by hypermail 2.1.6 : Mon Jul 17 2006 - 08:50:57 PDT