massive star feedback – from the first stars to the present
DESCRIPTION
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 ?. - PowerPoint PPT PresentationTRANSCRIPT
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