3D Radiation Hydrodynamic
Simulations of Massive Star Envelopes

Yan-Fei Jiang（姜燕飞）Center for Computational Astrophysics,
Flatiron InstituteOutline• Challenges for 1D models of massive star Envelopes• 3D vs. 1D models• Numerical Schemes for 3D Radiation (Magneto-)Hydrodynamic
Simulations• What can we learn about massive stars based on 3D Radiationhydrodynamic Simulations:• Continuum radiation driven mass loss
• Turbulent pressure support in envelope• Impact of 3D RSG Structures on Shock Breakout Signals(Jared’s talk).
• Stochastic low frequency variabilities• Broad band Spectra from the simulations• Improve 1D stellar evolution models of massive stars

Traditional 1D Stellar Evolution
Models of Massive Stars
Jiang et al. (2018)
Goldberg et al. (2022)

Luminosity
E ective Temperatureff• What is the alpha value for MLT• What causes the variability and mass loss long before SN

1D Models can be very uncertain
Yusof et al. (2013)
Köhler et al. (2015)

ZAMS

BonnGeneva• Di erent treatment

ff

ff

ffof surface
convection canresult in quite
di erent radii ande ectivetemperature.

Super-Eddington due to the opacitypeaks

Paxton et al. (2013)
Jiang et al. (2015)

HHeFe

constantdensity lines

Opacity Peaks cause near surface
convection zone
Cantiello et al. (2021)

Is this truly stable and quiet?

MESA model

Ubiquitous to nearly
all massive stars
throughout many
stages of their
lifetime

Put the star in 3D
Jiang et al. (2012, 2014)
Jiang (2021,2022)• 3D (Magneto-)hydrodynamics for ideal gas• Solving the time-dependent Boltzmann equation forradiative transfer• Should be able to handle both optically thick andoptically thin conditions• Gas and photons are thermally and dynamically coupled
self-consistently.
• No mixing length type convection model• No radiation force due to ultraviolet lines in the opticallythin regime

Radiation Transport

Jiang (2021,2022)•Speci c intensity is a function of time, spatial location,
angular directions and frequency•Properties of the equation can change dramatically depends
on the source termfi• Frequency dependence is now added via the multi-group approachRadiation Transport
Skartlien (2000);•The short characteristic approach

Freytag et al. (2012)
Anusha et al. (2021)
Witzke et al. (2021)
Moens et al. (2022)•Cannot really include radiation pressure•Velocity dependence is also typically neglected• The moment approachfiff•Take angular moments of speci c intensities•Close the moments using a closure relation•The commonly used di usion approximation does not reallywork near the photosphere.

Model Selection

Saturation State Depends on Locationsin the HR diagram Jiang et al. (2015)

Saturation State Depends on Locationsin the HR diagram Jiang et al. (2015)

Jiang et al. (2018)

Space-Time Structures of theEnvelope
M80T9L6.2

Ω/Ω0Extended
Envelope

v/cg,0log(r/rØ)Density

104

Supersonicturbulence

102

2.5

100

2.010°210°4

1.5

Turbulentvelocitylog(r/rØ)

102

2.5
10

2.0
1.5010°2log(r/rØ)

101
100

2.0
10°1

1.5log(r/rØ)

101

2.5

Opacity

2.0
1.5
100

100

110

120

130
140
150
t/4.26 hours

160

170

∑/∑0

Temperature

Tr /T02.5

He peakFe peakComparison Run

Comparison Run
M80T19L6.4

2.5log(r/rØ)

104

2.0

10°2

1.5

10°4

2.5log(r/rØ)Turbulentvelocity

1022.0v/cg,0Density

100

Ω/Ω0102

100

1.5
10°2

2.5
2.0

Tr /T0log(r/rØ)Temperature

101

100

1.5
10°1

2.5

∑/∑0log(r/rØ)Opacity

101

2.0
1.5
120

100

140160180t/4.26 hours

200

Opacitypeaks areweakerContinuum Radiation Driven
Mass Loss Rate
• In the steady state, cooler star can drive mass loss rate
• Mass loss rate for the hotter star in the steady state issmaller

Consequences of 3D turbulence• Signi cant turbulent pressure near the photospherefiMSZAMSRSGConsequences of 3D turbulence
Shultz et al. (2020)• Reduction of radiation force due to correlated uctuations
1Dfl3D

Red Supergiants

EntropyLuminosity

Turbulent Pressure

Goldberg, Jiang & Bildsten (2021)

Connect 3D Simulations with Observations:
Variability

Burssens et al (2020)

Bowman et al (2020)

1.Internal gravity waves (IGWs)
2. Near Surface Convective Zones (CZs)

Variability Properties of the
Simulated StarssHR

E ective Temperature

ff

Schultz, Bildeten, Jiang (2022)

Variability Properties of the
Simulated Stars

Schultz, Bildeten, Jiang (2022)

Variability Properties of the
Simulated Stars

Schultz, Bildeten, Jiang (2022)

Connect 3D Simulations with Observations:
Broadband spectra

Preliminary!

From 3D Simulations to 1D Modeling• Reduction of radiation force due to convection• Correct formula for convectiveenergy transport• Signi cant turbulent pressure
support near the photospherefiSchultz, Bildsten & Jiang (2020)