Journal Article

Turn-off of deuterium astration in the recent star formation of the Galaxy disc

T. Tsujimoto

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 4, pages 2540-2548
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI:
Turn-off of deuterium astration in the recent star formation of the Galaxy disc

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Chemical features of the local stellar disc have firmly established that long-term, continuous star formation has been accompanied by a steady rate of accretion of low-metallicity gas from the halo. We now argue that the recent discovery of an enhanced deuterium (D) fraction in the Galaxy is consistent with this picture. We consider two processes: the destruction of D in the interior of stars (astration) and the supply of nearly primordial D associated with the gas infall. Conventional Galactic chemical evolution models predict a monotonic decrease in D/H with time with a present-day D/H abundance which is much lower than the local value recently revealed. This predicted feature is the result of high levels of deuterium astration involved in the formation of the local metal-enhanced disc. Here we propose a new channel to explain the observed enhancement in D/H. Our model, which invokes ongoing gaseous infall and a star formation rate that declines over the past several Gyr, predicts that the D astration is suppressed over the same time interval.

Keywords: stars: abundances; ISM: abundances; Galaxy: disc; Galaxy: evolution

Journal Article.  7576 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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