A Transparent Window into Early-Type Stellar Variability

Abstract

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 stars. Here we demonstrate that these convection zones are \emph{not} present in as wide a range of stars as previously believed. In particular, there are regions which 1D stellar evolution models report to be convectively unstable but which fall below the critical Rayleigh number for onset of convection. For sub-solar metallicity this opens up a \emph{stability window} in which there are no subsurface convection zones. For LMC metallicity this surface stability region extends roughly between $8M_{\odot }$ and $16M_{\odot }$, increasing to $8M_{\odot }$ -- $35M_{\odot }$ for SMC metallicity. Such windows are then an excellent target for probing the relative influence of subsurface convection and other sources of photometric variability in massive stars.

arXiv comment9 pages, 4 figures. Accepted in ApJ

References in corpus (21)

• The NumPy array: a structure for efficient numerical computation
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Low Temperature Opacities
• Shell-model calculations of stellar weak interaction rates: II. Weak rates for nuclei in the mass range A=45-65 in supernovae environment
• Mass loss from hot massive stars
• Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
• Sub-surface convection zones in hot massive stars and their observable consequences
• Bright OB stars in the Galaxy - III. Constraints on the radial stratification of the clumping factor in hot star winds from a combined Halpha, IR and radio analysis
• Thermodynamic functions of dense plasmas: analytic approximations for astrophysical applications
• Coulomb tunneling for fusion reactions in dense matter: Path integral Monte Carlo versus mean field
• Magnetic spots on hot massive stars
• On the Magnetic Prandtl Number Behavior of Accretion Disks
• Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150 and HD 46966
• On the photometric detection of Internal Gravity Waves in upper main-sequence stars I. Methodology and application to CoRoT targets
• Envelope Convection, Surface Magnetism and Spots in A- and late B-type Stars
• Low-frequency variability in massive stars: Core generation or surface phenomenon?
• Stochastic light variations in hot stars from wind instability: Finding photometric signatures and testing against the TESS data

Cited by in corpus (7)

• Convective boundary mixing in main-sequence stars: theory and empirical constraints
• An Atlas of Convection in Main-Sequence Stars
• The photometric variability of massive stars due to gravity waves excited by core convection
• Photometric detection of internal gravity waves in upper main-sequence stars. III. Comparison of amplitude spectrum fitting and Gaussian process regression using celerite2
• The Initial Magnetic Field Distribution in AB Stars
• Variability of Galactic blue supergiants observed with TESS
• Binarity at LOw Metallicity (BLOeM): massive star variability revealed using a novel software tool for point-spread function fitting of TESS images