A Definitive Test of Rotational Mixing in Massive Stars
Abstract
CNO processed surface material found in OB stars may originate either from internal mixing or from binary interaction, but incomplete boron depletion is an unambiguous sign of internal mixing. Existing boron observations indeed suggest that internal mixing occurs in some stars at a level that is consistent with the low end of the efficiency range predicted by the different models of rotationally driven mixing. However, current results are too sparse to directly confirm the expected relation between boron depletion and rotation, and leave room to interpret boron depletion through other mixing processes. We propose to observe boron in ten rather rapidly rotating early-B stars in the 10 Myr old open cluster NGC 3293. Together with our previous data on stars in this cluster, this increased sample with an expanded range of V sin(i) values will provide a definitive test of rotational mixing, and --- assuming that rotation actually drives the expected mixing --- will allow for a tight calibration of its efficiency, which is of critical importance for modeling the interior of massive stars, with wide implications for their advanced evolutionary stages.
- Publication:
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HST Proposal
- Pub Date:
- June 2016
- Bibcode:
- 2016hst..prop14673P