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Bowman et al. (2019) reported low-frequency photometric variability in 164 O- and B-type stars observed with K2 and TESS. They interpret these motions as internal gravity waves, which could be excited stochastically by convection in the…

The outer envelopes of massive ($M\gtrsim10\,M_{\odot}$) stars exhibit large increases in opacities from forests of lines and ionization transitions (particularly from iron and helium) that trigger near-surface convection zones.…

Solar and Stellar Astrophysics · Physics 2023-07-19 William Schultz , Lars Bildsten , Yan-Fei Jiang

Doubly diffusive convection is considered in a vertical slot where horizontal temperature and solutal variations provide competing effects to the fluid density while allowing the existence of a conduction state. In this configuration, the…

Fluid Dynamics · Physics 2023-01-24 C. Beaume , A. M. Rucklidge , J. Tumelty

Double-diffusive convection refers to mixing where the effects of thermal and composition gradients compete to determine the stability of a fluid. In addition to the familiar fast convective instability, such fluids exhibit the slow, direct…

Astrophysics · Physics 2015-06-24 Scott A. Grossman , Ronald E. Taam

Stellar evolution calculations have had great success reproducing the observed atmospheric properties of different classes of stars. Recent detections of g-mode pulsations in evolved He burning stars allow a rare comparison of their…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jan-Torge Schindler , Elizabeth M. Green , W. David Arnett

Direct numerical simulations have been performed for turbulent thermal convection between horizontal no-slip, permeable walls with a distance $H$ and a constant temperature difference $\Delta T$ at the Rayleigh number…

Fluid Dynamics · Physics 2020-04-21 Koki Kawano , Shingo Motoki , Masaki Shimizu , Genta Kawahara

The goal of stellar evolution theory is to predict the structure of stars throughout their lifetimes. Usually, these predictions can be assessed only indirectly, for example by comparing predicted and observed effective temperatures and…

Solar and Stellar Astrophysics · Physics 2019-12-18 Earl P. Bellinger , Sarbani Basu , Saskia Hekker , Jørgen Christensen-Dalsgaard

We study the convection zones in the outer envelope of hot massive stars which are caused by opacity peaks associated with iron and helium ionization. We determine the occurrence and properties of these convection zones as function of the…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. Cantiello , N. Langer , I. Brott , A. de Koter , S. N. Shore , J. S. Vink , A. Voegler , D. J. Lennon , S. -C. Yoon

Most analytic work to date on protostellar disks has focused on those in isolation from their environments. However, observations are now beginning to probe the earliest, most embedded phases of star formation, during which disks are…

Astrophysics · Physics 2009-11-13 Kaitlin M. Kratter , Christopher D. Matzner , Mark R. Krumholz , .

We couple two-dimensional hydrodynamics to detailed one-dimensional multigroup flux-limited diffusion neutrino transport to investigate prompt convection in core collapse supernovae. Our initial conditions, time-dependent boundary…

(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

Subsurface convection zones are ubiquitous in early-type stars. Driven by narrow opacity peaks, these thin convective regions transport little heat but play an important role in setting the magnetic properties and surface variability of…

Solar and Stellar Astrophysics · Physics 2022-03-09 Adam S. Jermyn , Evan H. Anders , Matteo Cantiello

We report on the development of an implicit multi-D hydrodynamic code for stellar evolution. We present two test-cases relevant for the first scientific goal of the code: the simulation of convection in pulsating stars. First results on a…

With the rapid development of asteroseismology thanks to space-based photometry missions such as CoRoT, Kepler, TESS, and in the future, PLATO, and the use of inversion techniques, quasi-model-independent constraints on the stellar…

Solar and Stellar Astrophysics · Physics 2022-07-20 J. Bétrisey , G. Buldgen

We present a detailed study of the small frequency separations as diagnostics of the mass of the convective core and evolutionary stage of solar-type stars. We demonstrate how the small separations can be combined to provide sensitive tests…

Astrophysics · Physics 2009-11-11 Anwesh Mazumdar , Sarbani Basu , Braxton L. Collier , Pierre Demarque

We compute rotating 1D stellar evolution models that include a modified temperature gradient in convection zones and criterion for convective instability inspired by rotating 3D hydrodynamical simulations performed with the MUSIC code. In…

Solar and Stellar Astrophysics · Physics 2021-10-27 Thomas Constantino , Isabelle Baraffe , Thomas Goffrey , Jane Pratt , Thomas Guillet , Dimitar Vlaykov , Louis Amard

Artificially increasing the luminosity and the thermal diffusivity of a model is a common tactic adopted in hydrodynamical simulations of stellar convection. In this work, we analyse the impact of these artificial modifications on the…

Solar and Stellar Astrophysics · Physics 2022-04-20 A. Le Saux , T. Guillet , I. Baraffe , D. G. Vlaykov , T. Constantino , J. Pratt , T. Goffrey , M. Sylvain , V. Réville , A. S. Brun

Water's density maximum at 4C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4C, but stably stratified above 4C. We present numerical…

Solar and Stellar Astrophysics · Physics 2015-06-19 Daniel Lecoanet , Michael Le Bars , Keaton J. Burns , Geoffrey M. Vasil , Benjamin P. Brown , Eliot Quataert , Jeffrey S. Oishi

Overshooting occurs in stars when convective elements penetrate into adjacent radiative zones. In the Sun, it leads to the so-called `tachocline' at the base of the outer convection zone and this region is becoming a key ingredient of the…

Solar and Stellar Astrophysics · Physics 2010-01-07 B. Dintrans

Intermediate-mass main sequence stars have large radiative envelopes overlying convective cores. This configuration allows internal gravity waves (IGWs) generated at the convective-radiative interface to propagate towards the stellar…

Solar and Stellar Astrophysics · Physics 2020-08-12 R. P. Ratnasingam , P. V. F. Edelmann , T. M. Rogers