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Determinations of the \he3 concentrations in Galactic matter serve to impose interesting and important constraints both on cosmological models and on models of Galactic chemical evolution. At present, observations of \he3 in the solar…

Astrophysics · Physics 2009-09-15 Sean T. Scully , Michel Casse , Keith A. Olive , D. N. Schramm , J. Truran , E. Vangioni-Flam

To reconcile the measurements of 3He/H in Galactic HII regions with high values of 3He in a couple of planetary nebulae, we propose that thermohaline mixing is inhibited by a fossil magnetic field in red giant stars that are descendants of…

Astrophysics · Physics 2009-11-13 Corinne Charbonnel , Jean-Paul Zahn

We recall the emergence of the ``3He problem'', its currently accepted solution, and we summarize the presently available constraints on models of stellar nucleosynthesis and studies of Galactic chemical evolution from measurements of the…

Astrophysics · Physics 2007-05-23 Daniele Galli

We examine the galactic chemical evolution (GCE) of $^3\rm{He}$ in one-zone and multi-zone models, with particular attention to the stellar yields and GCE parameters that can reproduce both the protosolar $^3\rm{He}$ abundance and recent…

Astrophysics of Galaxies · Physics 2026-04-03 Miqaela K. Weller , David H. Weinberg

Thermohaline mixing is a favoured mechanism for the so-called "extra mixing" on the red giant branch of low-mass stars. The mixing is triggered by the molecular weight inversion created above the hydrogen shell during first dredge-up when…

Solar and Stellar Astrophysics · Physics 2017-06-28 Kate Henkel , Amanda I. Karakas , John C. Lattanzio

Based on spectroscopic constraints derived from NLTE line formation, we explore the likely range of stellar parameters (T_eff and log g) for the hyper-metal-poor (HMP) star HE 1327-2326. Combining the constraints from Balmer line profiles…

Solar and Stellar Astrophysics · Physics 2011-02-11 A. J. Korn , O. Richard , L. Mashonkina , M. S. Bessell , A. Frebel , W. Aoki

First results of our 3D numerical simulations of thermohaline convection driven by 3He burning in a low-mass RGB star at the bump luminosity are presented. They confirm our previous conclusion that this convection has a mixing rate which is…

Solar and Stellar Astrophysics · Physics 2015-05-20 Pavel A. Denissenkov , William J. Merryfield

There is an apparent dichotomy between the metal-poor ([Fe/H] <= -2) yet carbon-normal giants and their carbon-rich counterparts. The former undergo significant depletion of carbon on the red giant branch after they have undergone first…

Solar and Stellar Astrophysics · Physics 2015-05-13 Richard J. Stancliffe , Ross P. Church , George C. Angelou , John C. Lattanzio

(abbreviated) The evolution of intermediate mass stars at very low metallicity during their final thermal pulse asymptotic giant branch phase is studied in detail. As representative examples models with initial masses of 4Msun and 5Msun…

Astrophysics · Physics 2009-11-10 Falk Herwig

While all models for the evolution of galaxies require the accretion of gas to sustain their growth via on-going star formation, it has proven difficult to directly detect this inflowing material. In this paper we use data of nearby…

Thermohaline mixing has recently been proposed to occur in low mass red giants, with large consequence for the chemical yields of low mass stars. We investigate the role of thermohaline mixing during the evolution of stars between 1 Msun…

Astrophysics · Physics 2008-11-26 M. Cantiello , H. Hoekstra , N. Langer , A. J. T. Poelarends

We demonstrate that among the potential sources of the primordial abundance variations of the proton-capture elements in globular-cluster stars proposed so far, such as the hot-bottom burning in massive AGB stars and H burning in the…

Solar and Stellar Astrophysics · Physics 2015-06-22 Pavel Denissenkov , Don VandenBerg , David Hartwick , Falk Herwig , Achim Weiss , Bill Paxton

We summarize panchromatic Extragalactic Background Light data to place upper limits on the integrated near-infrared surface brightness (SB) that may come from Population III stars and possible accretion disks around their stellar-mass black…

Recent near-IR power-spectra and panchromatic Extragalactic Background Light measurements provide upper limits on the near-IR surface brightness (SB>31 mag/arcsec^2) that may come from Pop III stars and accretion disks around resulting…

Motivated by recent theoretical work suggesting that a substantial fraction of Population (Pop) III stars may have had masses low enough for them to survive to the present day, we consider the role that the accretion of metal-enriched gas…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Jarrett L. Johnson , Sadegh Khochfar

While Population III stars are typically thought to be massive, pathways towards lower-mass Pop III stars may exist when the cooling of the gas is particularly enhanced. A possible route is enhanced HD cooling during the merging of…

Astrophysics of Galaxies · Physics 2015-06-18 S. Bovino , M. A. Latif , T. Grassi , D. R. G. Schleicher

Very high-energy gamma-rays (VHE; E>100 GeV) have been detected from the direction of the Galactic Centre up to energies E>10 TeV. Up to now, the origin of this emission is unknown due to the limited positional accuracy of the observing…

Astrophysics of Galaxies · Physics 2010-02-12 A. Abramowski , S. Gillessen , D. Horns , H. -S. Zechlin

Low mass stars (< 2-2.5 M_sun) exhibit, at all the stages of their evolution, signatures of processes that require challenging modeling beyond the standard stellar theory. In this paper we focus on their peculiarities while they climb the…

Astrophysics · Physics 2016-08-30 Corinne Charbonnel , Ana Palacios

Constraining the properties of Population III (Pop III) stars will be very challenging because they reside in small galaxies at high redshift which will be difficult to directly detect. In this paper, we suggest that intensity mapping may…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-01 Eli Visbal , Zoltan Haiman , Greg L. Bryan

Current numerical studies suggest that the first galaxies formed a few stars at a time and were enriched only gradually by the first heavy elements. However, the large box sizes in these models cannot resolve primordial supernova explosions…

Astrophysics · Physics 2009-11-13 Daniel Whalen , Bob Van Veelen , Brian W. O'Shea , Michael L. Norman