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  • NAM2017
    • Timetable
    • Delegates
    • Registration
  • Science
    • Parallel sessions
    • Plenary talks
    • Posters
    • Publishing workshop
    • Media workshop
    • Community forum
    • Special lunches
    • Hack day
  • Social
    • Welcome reception
    • Conference dinner
    • Football + BBQ evening
  • Outreach
    • Public talk
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Tuesday

Abstract

id
Can the Chemical Evolution of the Galaxy Solve the Mystery of Oxygen in Red Giants?
Galactic Chemical Evolution, Stars, and the Creation of Elements in the Big-Data Era
Date Submitted
2017-04-12 16:36:59
Ghina M. Halabi
Institute of Astronomy
Red giants experience recurrent mixing events that significantly alter the chemical composition of their envelopes. Inspecting changes in surface abundances allows us to probe the physical processes happening in the deep stellar interiors. Of particular importance are the three main oxygen isotopes which are altered in the course of the CNO-cycle and serve as indicators of the nucleosynthesis and mixing taking place.

In this contribution, I show that the predicted 16O/17O and 16O/18O from stellar models of red giants are at variance with observations (Halabi et al. 2015). This discrepancy puts two main uncertainties in stellar evolution models in the spotlight: convective boundary mixing and relevant nuclear reaction rates.
Owing to the steep profile of the 17O isotope inside the star, 16O/17O is very sensitive to the depth of convective mixing. On the other hand, the 17O destruction rates have been recently re-measured by the LUNA collaboration (Bruno et al. 2016).

I will discuss whether extra mixing or the new nuclear reaction rates can resolve the discrepancy between theory and observations.
Another suggested possible solution to match observations is assuming slightly supersolar initial 17O and 18O abundances instead of the solar values, combined with a subsolar initial 16O abundance (Lebzelter et al. 2015). I will show whether this agrees with predictions from galactic chemical evolution models and how exploring such significant deviations from model predictions may provide insight into the cosmic recycling of matter.

Schedule

id
date time
13:30 - 15:00
14.38
Abstract
Can the Chemical Evolution of the Galaxy Solve the Mystery of Oxygen in Red Giants?
Tuesday
Larkin LT-D

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