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Full-Text Articles in Physical Sciences and Mathematics
Simulating The Outer Layers Of Rapidly Rotating Stars, Frank J. Robinson, Joel Tanner, Sarbani Basu
Simulating The Outer Layers Of Rapidly Rotating Stars, Frank J. Robinson, Joel Tanner, Sarbani Basu
Chemistry & Physics Faculty Publications
This paper presents the results of a set of radiative hydrodynamic (RHD) simulations of convection in the near-surface regions of a rapidly rotating star. The simulations use microphysics consistent with stellar models, and include the effects of realistic convection and radiative transfer. We find that the overall effect of rotation is to reduce the strength of turbulence. The combination of rotation and radiative cooling creates a zonal velocity profile in which the motion of fluid parcels near the surface is independent of rotation. Their motion is controlled by the strong up and down flows generated by radiative cooling. The fluid …
The Pre-Roche Lobe Overflow Evolution Of Massive Close Binary Stars: A Study Of Rotation, Wind Enhanced Mass-Loss, And The Bi-Stability Jump, Thomas C. Gehrman Jr.
The Pre-Roche Lobe Overflow Evolution Of Massive Close Binary Stars: A Study Of Rotation, Wind Enhanced Mass-Loss, And The Bi-Stability Jump, Thomas C. Gehrman Jr.
All Graduate Theses, Dissertations, and Other Capstone Projects
Massive stars have the ability to enrich their environment with heavy elements and influence star formation in galaxies. Some massive stars exist in binary systems with short orbital periods. These are called massive close binaries. It is important to understand the evolution of massive close binary systems to gain insight about galaxy evolution. Massive stars above 20 solar masses experience a bi-stability jump where there is a sudden increase in mass-loss rate in their winds. There is ongoing research in this field, but the study of the bi-stability jump and its effects on massive close binary star properties has not …
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
ETSU Faculty Works
Massive star winds are complex radiation-hydrodynamic (sometimes magnetohydrodynamic) outflows that are propelled by their enormously strong luminosities. The winds are often found to be structured and variable, but can also display periodic or quasi-periodic behavior in a variety of wind diagnostics. The regular variations observed in putatively single stars, especially in UV wind lines, have often been attributed to corotating interaction regions (CIRs) like those seen in the solar wind. We present light curves for variable polarization from winds with CIR structures. We develop a model for a time-independent CIR based on a kinematical description. Assuming optically thin electron scattering, …
From Canonical To Enhanced Extra Mixing In Low‐Mass Red Giants: Tidally Locked Binaries, Pavel A. Denissenkov, Brian Chaboyer, Ke Li
From Canonical To Enhanced Extra Mixing In Low‐Mass Red Giants: Tidally Locked Binaries, Pavel A. Denissenkov, Brian Chaboyer, Ke Li
Dartmouth Scholarship
Stellar models that incorporate simple diffusion or shear-induced mixing are used to describe canonical extra mixing in low-mass red giants of low and solar metallicity. These models are able to simultaneously explain the observed Li and CN abundance changes along the upper red giant branch (RGB) in field low-metallicity stars and match photometry, rotation, and 12C/13C ratios for stars in the old open cluster M67. The shear mixing model requires that main-sequence (MS) progenitors of upper RGB stars possessed rapidly rotating radiative cores and that specific angular momentum was conserved in each of their mass shells during …
Sporadic Mass Ejection In Red Supergiants, Menas Kafatos, A. G. Michalitsianos
Sporadic Mass Ejection In Red Supergiants, Menas Kafatos, A. G. Michalitsianos
Mathematics, Physics, and Computer Science Faculty Articles and Research
We have applied a general mechanism first proposed by J. A. Burke to red supergiants for determining the spin-down rate and angular momentum loss of rotating stars. This model relies principally on sporadic mass ejection, which is assumed to be the result of turbulent elements accelerating material in cool supergiant.atmospheres. Mass is preferentially expelled in the forward direction of rotation, resulting in a rapid loss of angular momentum on time scales of 1Q^4-10^6 years in the supergiant evolutionary phase. Such rotational breaking will occur if the turbulent elements have characteristic sizes a few percent of the stellar radius, and rms …