Effects of thermohaline instability and rotation-induced mixing on the evolution of light elements in the Galaxy : D, 3He and 4He

Abstract

Recent studies of low- and intermediate-mass stars show that the evolution of the chemical elements in these stars is very different from that proposed by standard stellar models. Rotation-induced mixing modifies the internal chemical structure of main sequence stars, although its signatures are revealed only later in the evolution when the first dredge-up occurs. Thermohaline mixing is likely the dominating process that governs the photospheric composition of low-mass red giant branch stars and has been shown to drastically reduce the net 3He production in these stars. The predictions of these new stellar models need to be tested against galaxy evolution. In particular, the resulting evolution of the light elements D, 3He and 4He should be compared with their primordial values inferred from the Wilkinson Microwave Anisotropy Probe data and with the abundances derived from observations of different Galactic regions. We study the effects of thermohaline mixing and rotation-induced mixing on the evolution of the light elements in the Milky Way. We compute Galactic evolutionary models including new yields from stellar models computed with thermohaline instability and rotation-induced mixing. We discuss the effects of these important physical processes acting in stars on the evolution of the light elements D, 3He, and 4He in the Galaxy. Galactic chemical evolution models computed with stellar yields including thermohaline mixing and rotation fit better observations of 3He and 4He in the Galaxy than models computed with standard stellar yields. The inclusion of thermohaline mixing in stellar models provides a solution to the long-standing "3He problem" on a Galactic scale. Stellar models including rotation-induced mixing and thermohaline instability reproduce also the observations of D and 4He.

12 pages, 9 figures, accepted for publication in A&A

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Cited by in corpus (23)

• Metal-Poor Stars Observed with the Magellan Telescope I. Constraints on Progenitor Mass and Metallicity of AGB Stars Undergoing s-Process Nucleosynthesis
• On the Numerical Treatment and Dependence of Thermohaline Mixing in Red Giants
• The Gaia-ESO survey: impact of extra-mixing on C- and N-abundances of giant stars
• The thermohaline, Richardson, Rayleigh-Taylor, Solberg-Hoiland, and GSF criteria in rotating stars
• Population synthesis to constrain Galactic and Stellar Physics- I- Determining age and mass of thin-disc red-giant stars
• On the Deuterium-to-Hydrogen Ratio of the Interstellar Medium
• Models of red giants in the CoRoT asteroseismology fields combining asteroseismic and spectroscopic constraints
• On the cosmic evolution of the specific star formation rate
• The most metal-rich stars in the universe: chemical contributions of low and intermediate mass asymptotic giant branch stars with metallicities between $0.04\le Z\le \mathrm{0.10.}$
• Green Bank Telescope Observations of 3He+: HII Regions
• A High Precision Survey of the D/H Ratio in the Nearby Interstellar Medium
• Bridging the Gap between Intermediate and Massive Stars I: Validation of MESA against the State-of-the-Art Monash Stellar Evolution Program for a 2$M_{\odot }$ AGB Star
• On the deuterium abundance and the importance of stellar mass loss in the interstellar and intergalactic medium
• Varying physical constants and the lithium problem
• Pre-main sequence accretion and the formation of multiple populations in Globular Clusters
• Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet
• Green Bank Telescope Observations of ${}^3\mathbf{H}{\mathbf{e}}^{+}$: Planetary Nebulae
• Do All Low-Mass Stars Undergo Extra Mixing Processes?
• Uncertainties in models of stellar structure and evolution
• 3He: Does the problem persists?
• Surface C, N, O, and Na abundances of RR Lyrae variables implying the nature of internal mixing in low-mass stars
• Modelling the chemical evolution of the Milky Way
• Primordial helium-3 redux: The helium isotope ratio of the Orion nebula