The Cosmic Dust from whence we came:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Jan 30, 2017.

  1. paddoboy Valued Senior Member

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    Cosmic dust that formed our planets traced to giant stars
    January 30, 2017
    Scientists have identified the origin of key stardust grains present in the dust cloud from which the planets in our Solar System formed, a study suggests.


    Researchers have solved a long-standing puzzle concerning the source of the grains, which formed long before our Solar System and can be recovered from meteorites that fall to Earth.

    The stars that produced the dust were identified by observing how key reactions shaped the make-up of the grains, scientists say.

    During their lifetime, stars around six times larger than the Sun - called Asymptotic Giant Branch or AGB stars - blow off their outer layers, forming an interstellar cloud of gas and dust grains.



    Read more at: https://phys.org/news/2017-01-cosmic-planets-giant-stars.html#jCp
     
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  3. paddoboy Valued Senior Member

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    http://www.nature.com/articles/s41550-016-0027

    Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17/O:


    Abstract
    Stardust grains recovered from meteorites provide high-precision snapshots of the isotopic composition of the stellar environment in which they formed 1 . Attributing their origin to specific types of stars, however, often proves difficult. Intermediate-mass stars of 4–8 solar masses are expected to have contributed a large fraction of meteoritic stardust 2,3 . Yet, no grains have been found with the characteristic isotopic compositions expected for such stars 4,5 . This is a long-standing puzzle, which points to serious gaps in our understanding of the lifecycle of stars and dust in our Galaxy. Here we show that the increased proton-capture rate of 17O reported by a recent underground experiment 6 leads to 17O/16O isotopic ratios that match those observed in a population of stardust grainsfor proton-burning temperatures of 60–80 MK. These temperatures are achieved at the base of the convective envelope during the late evolution of intermediate-mass stars of 4–8 solar masses 7,8,9 , which reveals them as the most likely site of origin of the grains. This result provides direct evidence that these stars contributed to the dust inventory from which the Solar System formed.

     
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