Constraining the shape of convective core overshooting using slowly pulsating B-type stars May Gade Pedersen Supervisor and promoter Prof. Dr. Conny Aerts Co-supervisor Dr. Péter I. Pápics Collaborator: Dr. Tamara Rogers Stellar Hydro Days IV Victoria, Canada 30 May, 2017
The chemical factories of the Universe Credit: LucasVB/Wikimedia OB-type stars Production of heavy elements Fed back to environment Influences e.g. Credit: NASA Formation of stars and planetary systems Evolution of galaxies and the Universe
The chemical factories of the Universe Common feature Convective core Fully mixed More fuel High sensitivity to near core mixing processes! Credit: Adapted from www.sun.org
The chemical factories of the Universe Internal mixing processes Convective core overshooting Rotation Major problem! Poorly known and constrained! High uncertainty in stellar structure and evolution models! Credit: Adapted from www.sun.org
Asteroseismology using g-modes O B A FG K M B3-B8 High-order g-modes P = 0.8-3 days Luminosity Slowly Pulsating B-type (SPB) stars Why gravity-modes? Probe near-core regions Sensitive to changes in dp series (same ℓ, m) Δ μ Temperature Figure courtesy Péter I. Pápics
Asteroseismology using g-modes Slowly Pulsating B-type (SPB) stars B3-B8 High-order g-modes P = 0.8-3 days SPB star Why gravity-modes? Probe near-core regions Sensitive to changes in dp series (same ℓ, m) Δ μ Pápics et al. 2016
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes
Asteroseismology using g-modes Δ Mixing changes μ!
Theoretical period spacing series Stellar model for specific input physics Step overshoot Exp. overshoot Theoretical pulsation mode properties Ext. Exp. overshoot
Effect on stellar evolution
Effect on stellar evolution
Effect on stellar evolution
Step overshoot Diffusive mixing in overshooting region given as For dr αovhp,cc: r0: Convection Overshooting MESA: f0 D0
Exponential overshoot Diffusive mixing in overshooting region cc r0: Convection Overshooting MESA: f0 D0
Extended exponential overshoot Diffusive mixing in overshooting region For dr dr2: cc For dr > dr2: cc r0: Convection Overshooting MESA: f0 D0 D2 dr2
Varying f0 (i.e. D0) f0 D0
Varying f0 (i.e. D0) Step overshoot Exponential overshoot
Varying f0 (i.e. D0) Step overshoot Exponential overshoot
Varying f0 (i.e. D0) Step overshoot Exponential overshoot Xc = 0.50
Varying αov and f Strength
Varying αov and f Step overshoot Exponential overshoot
Varying αov and f Step overshoot Exponential overshoot
Varying αov and f Step overshoot Exponential overshoot
Varying Dext Extra mixing
Varying Dext Step overshoot Exponential overshoot
Varying Dext Step overshoot Exponential overshoot
Varying Dext Step overshoot Exponential overshoot
Varying f2 Extension Switch
Varying f2
Varying f2
Varying f2 Extended Exponential Overshoot Exponential overshoot w. Dext
Implementation of results from 2D hydrodynamical simulations of particle mixing
Implementation of results from 2D hydrodynamical simulations Set by f0 Set by fov Set as Dext Profile provided by Dr. Tamara Rogers
Implementation of results from 2D hydrodynamical simulations
Implementation of results from 2D hydrodynamical simulations
Implementation of results from 2D hydrodynamical simulations
Implementation of results from 2D hydrodynamical simulations
Conclusions Choice of core overshooting influences the evolution of stars Choice of f0 is important! Seismic modelling of period spacing series Constraints on strength and shape of core overshooting
Future work New SPB's Moravveji et al. 2015, 2016 Pápics et al. 2016
Thank you for your attention!
Varying f2 Extension Switch
Varying f2 Xc = 0.65
Varying f2 Xc = 0.35
Varying f2 Xc = 0.05