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Which physics determines the location of the mean molecular weight minimum in red giants?

Church, Ross LU ; Lattanzio, John; Angelou, George; Tout, Christopher A. and Stancliffe, Richard J. (2014) In Monthly Notices of the Royal Astronomical Society 443(2). p.977-984
Abstract
Stars ascending the red giant branch develop an inversion in mean molecular weight (mu) owing to the burning of He-3 in the region immediately above their hydrogen-burning shells. This inversion may drive thermohaline mixing and thereby be responsible for the extra mixing which is observationally indicated on the red giant branch. In this paper, we investigate the physical influences that determine the mass and temperature at which the inversion in mu develops. We find that it depends most strongly on the thermal structure of the envelope - the profiles of density and temperature in the region of the star immediately above the shell - and is otherwise relatively insensitive to abundances and nuclear reaction rates. The changes in the... (More)
Stars ascending the red giant branch develop an inversion in mean molecular weight (mu) owing to the burning of He-3 in the region immediately above their hydrogen-burning shells. This inversion may drive thermohaline mixing and thereby be responsible for the extra mixing which is observationally indicated on the red giant branch. In this paper, we investigate the physical influences that determine the mass and temperature at which the inversion in mu develops. We find that it depends most strongly on the thermal structure of the envelope - the profiles of density and temperature in the region of the star immediately above the shell - and is otherwise relatively insensitive to abundances and nuclear reaction rates. The changes in the effects of thermohaline mixing as stars proceed up the giant branch can mostly be understood in terms of their changing thermal structure, driven by their increasing core mass. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
methods: numerical, stars: abundances, stars: evolution
in
Monthly Notices of the Royal Astronomical Society
volume
443
issue
2
pages
977 - 984
publisher
Wiley-Blackwell
external identifiers
  • wos:000340436800004
  • scopus:84905672851
ISSN
1365-2966
DOI
10.1093/mnras/stu1195
language
English
LU publication?
yes
id
be08fe0e-bb95-4474-8e94-818cc3f618f0 (old id 4656193)
date added to LUP
2014-09-24 13:31:14
date last changed
2017-01-01 03:58:20
@article{be08fe0e-bb95-4474-8e94-818cc3f618f0,
  abstract     = {Stars ascending the red giant branch develop an inversion in mean molecular weight (mu) owing to the burning of He-3 in the region immediately above their hydrogen-burning shells. This inversion may drive thermohaline mixing and thereby be responsible for the extra mixing which is observationally indicated on the red giant branch. In this paper, we investigate the physical influences that determine the mass and temperature at which the inversion in mu develops. We find that it depends most strongly on the thermal structure of the envelope - the profiles of density and temperature in the region of the star immediately above the shell - and is otherwise relatively insensitive to abundances and nuclear reaction rates. The changes in the effects of thermohaline mixing as stars proceed up the giant branch can mostly be understood in terms of their changing thermal structure, driven by their increasing core mass.},
  author       = {Church, Ross and Lattanzio, John and Angelou, George and Tout, Christopher A. and Stancliffe, Richard J.},
  issn         = {1365-2966},
  keyword      = {methods: numerical,stars: abundances,stars: evolution},
  language     = {eng},
  number       = {2},
  pages        = {977--984},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Which physics determines the location of the mean molecular weight minimum in red giants?},
  url          = {http://dx.doi.org/10.1093/mnras/stu1195},
  volume       = {443},
  year         = {2014},
}