Massive star feedback – from the first stars to the present

Massive star feedback – from the first stars to the present

Jorick Vink (Imperial College London, UK)

Outline

• Why predict dM/dt ?

(as a function of Z?)

• Methods: CAK & Monte Carlo

• Results OB, LBV & WR winds

• Cosmological implications?

• Look into the Future

Why predict Mdot ?

• Energy & Momentum input into ISM

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

Evolution of a Massive Star

OB[e]

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution– Explosions: SN, GRBs

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution– Explosions: SN, GRBs– Final product: Neutron star, Black hole

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution– Explosions: SN, GRBs– Final product: Neutron star, Black hole– X-ray populations in galaxies

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar Spectra

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar Spectra – Analyses of starbursts

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar Spectra – Analyses of starbursts– Ionizing Fluxes

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar Spectra

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar Spectra

• Stellar “Cosmology”

From Scientific American

Why predict Mdot ?

• Energy & Momentum input into ISM

• Stellar Evolution

• Stellar spectra

• “Stellar cosmology”

Observations of the first stars

Goal: quantifying mass loss a function of Z (and z)

What do we know at solar Z ?

Radiation-driven wind by Lines

dM/dt = f (L, Mass, Temp, Z)

STAR Fe

Lucy & Solomon (1970) Castor, Abbott & Klein (1975) CAK

1. CAK Formalism

1. CAK Formalism

1. CAK Formalism

dM/dt & V(r)

1. CAK Formalism

Momentum problem in O star winds

A systematic discrepency

2. Monte Carlo approach

(Abbott & Lucy 1985)

Assumptions in line-force models

• Static

• One fluid

• Spherical

• Homogeneous, no clumps

Two O-star approaches

1. CAK-type Line force approximated

v(r) predicted CAK, Pauldrach (1986), Kudritzki (2002)

2. Monte Carlo V(r) adopted

Line force computed – for all radii multiple scatterings included

Abbott & Lucy (1985) Vink, de Koter & Lamers (2000,2001)

Monte Carlo Mass loss comparison

No systematic discrepency anymore ! (Vink et al. 2000)

Wind momentum-Luminosity relation O stars

(Vink et al. 2000)

B Supergiants Wind-Momenta

Vink et al. (2000)

The mass loss of LBVs

Vink & de Koter (2002)

Success of Monte Carlo at solar Z

• O-star Mass loss rates

• Prediction of the bi-stability jump

• Mass loss behaviour of LBVs

Monte Carlo mass-loss used in stellar models in Galaxy

dM/dt = f(Z): potential effects

• In CAK: dM/dt proportional to k = f(Z)

• Power-law exponent: log(dM/dt) = m log(Z)

• More ionization changes? (bi-stability)

• Power-law for all Z?

• Power-law flattening?

O star mass-loss Z-dependence

(Vink et al. 2001)

O star mass-loss Z-dependence

O star mass-loss Z-dependence

Which metals are important?

At lower Z : Fe CNO

solar Z

low Z

Fe

CNOH,He

Z-dependence of WR winds

Vink & de Koter (2005) astro-ph/0507352

Conclusions

• Successful MC Models at solar Z• O star winds are Z-dependent (Fe)• WR winds are Z-dependent (Fe) GRBs

• Low-Z WC models: flattening of this dependence• Below log(Z/Zsun) = -3 “Plateau”

Mass loss may play a role in early Universe

Future Work

• Solving momentum equation

• Compute Mdot at Z=0

• Wind Clumping

• Wind geometry at low Z

2-step Approach:

• Compute model atmosphere, ionization stratification, level populations

• Monte Carlo to compute radiative force (line and continuum opacity)

The bistability Jump

dM/dt increases by factor 5 Wind Density by factor 10 (Vink et al. 1999)

Mass lossRecipe

Consistent mass-loss rate

Non-consistent velocity law

Beta = 1

WC8

The First Stars

Credit: V. Bromm

Why predict Mdot ?

• Stellar evolution

- X-ray populations in galaxies

- Gamma-ray bursts

• Stellar spectra & ionizing fluxes

- Analyses of galaxy spectra

- Reionization of Universe

• Energy & Momentum input into ISM