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We present theoretical models of the angular momentum evolution of very low mass stars (0.1 - 0.5 M_sun) and solar analogues (0.6 - 1.1 M_sun). We investigate the effect of rotation on the effective temperature and luminosity of these…

Astrophysics · Physics 2009-07-28 Alison Sills , M. H. Pinsonneault , D. M. Terndrup

The present paper describes the behavior of the rotational velocity in metal--poor stars ([Fe/H]<-0.5 dex) in different evolutionary stages, based on Vsini values from the literature. Our sample is comprised of stars in the field and some…

Solar and Stellar Astrophysics · Physics 2010-09-28 C. Cortés , J. R. P. Silva , A. Recio-Blanco , M. Catelan , J. D. Do Nascimento , J. R. De Medeiros

I review aspects of the evolution of horizontal branch (HB) stars. I start by discussing current topics in the study of HB stellar evolution, including a brief review of the main determinants of the structure of low-mass core helium burning…

Astrophysics · Physics 2007-05-23 Ben Dorman

We study the distribution of exoplanets around main sequence (MS) stars and apply our results to the binary model for the formation of extreme horizontal branch (EHB; sdO; sdB; hot subdwarfs) stars. By Binary model we refer both to stellar…

Solar and Stellar Astrophysics · Physics 2015-05-18 Ealeal Bear , Noam Soker

Hot cluster Horizontal Branch (HB) stars and field subdwarf B (sdB) stars are core helium burning stars that exhibit abundance anomalies that are believed to be due to atomic diffusion. Diffusion can be effective in these stars because they…

Solar and Stellar Astrophysics · Physics 2015-06-03 G. Mathys , S. Hubrig , E. Mason , G. Michaud , M. Schoeller , F. Wesemael

Asteroseismology enabled measuring the rotation rate in the deep stellar interiors of stars across several evolutionary phases, advancing the theory of angular momentum transport in single stars from the main sequence to the white dwarf…

We study the angular momentum evolution of binaries containing two white dwarfs which merge and become cool helium-rich supergiants. Our object is to compare predicted rotation velocities with observations of highly evolved stars believed…

Astrophysics · Physics 2009-11-11 K. N. Gourgouliatos , C. S. Jeffery

We analyzed the behavior of the rotational velocity in the parent stars of extrasolar planets. Projected rotational velocity v sin i and angular momentum were combined with stellar and planetary parameters, for a unique sample of 147 stars,…

Solar and Stellar Astrophysics · Physics 2015-05-19 S. Alves , J. D. do Nascimento , J. R. De Medeiros

The evolution of rotating stars with zero-age main sequence (ZAMS) masses in the range 8 to 25 M_sun is followed through all stages of stable evolution. The initial angular momentum is chosen such that the star's equatorial rotational…

Astrophysics · Physics 2008-11-26 A. Heger , N. Langer , S. E. Woosley

We analyzed the behavior of the rotational velocity in the parent stars of extrasolar planets. Projected rotational velocity v sin i and angular momentum were combined with stellar and planetary parameters, for a unique sample of 147 stars,…

Solar and Stellar Astrophysics · Physics 2010-07-05 Sanzia Alves , Jose Dias do Nascimento , Jose Renan de Medeiros

Extreme helium stars are very rare low-mass supergiants in a late stage of evolution. They are probably contracting to become white dwarfs following a violent phase of evolution which caused them to become hydrogen-deficient giants,…

Solar and Stellar Astrophysics · Physics 2010-01-26 C. S. Jeffery W. -R. Hamann

Angular momentum is a key property regulating star formation and evolution. However, the physics driving the distribution of the stellar rotation rates of early-type main-sequence stars is as yet poorly understood. Using our catalog of…

Solar and Stellar Astrophysics · Physics 2021-11-24 Weijia Sun , Xiao-Wei Duan , Licai Deng , Richard de Grijs

Rotation in massive stars has been studied on the main sequence and during helium burning for decades, but only recently have realistic numerical simulations followed the transport of angular momentum that occurs during more advanced stages…

Astrophysics · Physics 2007-05-23 A. Heger , S. E. Woosley , N. Langer , H. C. Spruit

Oscillation modes of a mixed character are able to probe the inner region of evolved low-mass stars and offer access to a range of information, in particular, the mean core rotation. Ensemble asteroseismology observations are then able to…

Solar and Stellar Astrophysics · Physics 2024-01-17 B. Mosser , G. Dreau , C. Pincon , S. Deheuvels , K. Belkacem , Y. Lebreton , M-J. Goupil , E. Michel

We estimate the rotation speed of Population III (Pop III) stars within a minihalo at z ~ 20 using a smoothed particle hydrodynamics (SPH) simulation, beginning from cosmological initial conditions. We follow the evolution of the primordial…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Athena Stacy , Volker Bromm , Abraham Loeb

We derive a new expression for the coefficient $D_{\mathrm{h}}$ of diffusion by horizontal turbulence in rotating stars. This new estimate can be up to two orders of magnitude larger than given by a previous expression. As a consequence the…

Astrophysics · Physics 2011-05-23 André Maeder

High-resolution spectroscopic measurements of blue horizontal-branch stars in six metal-poor globular clusters -- M3, M13, M15, M68, M92, and NGC 288 -- reveal remarkable variations in photospheric composition and rotation velocity as a…

Astrophysics · Physics 2009-11-10 Bradford B. Behr

The understanding of the rotational evolution of early-type stars is deeply related to that of anisotropic mass and angular momentum loss. In this paper, we aim to clarify the rotational evolution of rapidly rotating early-type stars along…

Solar and Stellar Astrophysics · Physics 2019-05-22 D. Gagnier , M. Rieutord , C. Charbonnel , B. Putigny , F. Espinosa Lara

We have analyzed high dispersion and high precision spectra of 5 blue horizontal branch stars in the globular cluster M92 to establish that the projected rotational velocity for these stars ranges from 15 to 40 \kms. This is larger than…

Astrophysics · Physics 2009-10-30 J. G. Cohen , J. K. McCarthy

(Abbreviated) We have used precise radial velocity measurements of subdwarf-B stars from the Palomar-Green catalogue to look for binary extreme horizontal branch (EHB) stars. We identify 36 EHB stars in our sample and find that at least 21…

Astrophysics · Physics 2008-11-26 P. F. L. Maxted , U. Heber , T. R. Marsh , R. C. North