Transcript Massive star feedback – from the first stars to the present Jorick Vink (Keele University)

Massive star feedback – from the
first stars to the present
Jorick Vink (Keele University)
Outline
• Why predict Mass-loss rates?
(as a function of Z)
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Monte Carlo Method
Results OB, B[e], LBV & WR winds
Cosmological implications?
Look into the Future
Why predict Mdot ?
• Energy & Momentum input into ISM
Massive star feedback
NGC 3603
Why predict Mdot ?
• Energy & Momentum input into ISM
Why predict Mdot ?
• Energy & Momentum input into ISM
• Stellar Evolution
Evolution of a Massive Star
O
B[e]
Why predict Mdot ?
• Energy & Momentum input into ISM
• Stellar Evolution
– Explosions: SN, GRBs
Progenitor for Collapsar model
• Rapidly rotating
• Hydrogen-free star (Wolf-Rayet star)
Woosley (1993)
• But……
Progenitor for Collapsar model
• Rapidly rotating
• Hydrogen-free star (Wolf-Rayet star)
Woosley (1993)
• But……
Stars have winds…
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 ?
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Energy & Momentum input into ISM
Stellar Evolution
Stellar Spectra
Stellar “Cosmology”
From Scientific American
The First Stars
Credit: V. Bromm
The Final products of Pop III stars
(Heger et al. 2003)
From Scientific American
Why predict Mdot ?
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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
Lucy & Solomon (1970)
Castor, Abbott & Klein (1975) = CAK
Wind
STAR
dM/dt = f (Z, L, M, Teff)
Fe
Radiation-driven wind by Lines
Abbott & Lucy (1985)
dM/dt = f (Z, L, M, Teff)
Momentum problem in O star winds
A systematic discrepancy
Monte Carlo approach
Approach:
• Assume a velocity law
• Compute model atmosphere, ionization
stratification, level populations
• Monte Carlo to compute radiative force
Mass loss parameter study
Monte Carlo Mass loss comparison
No systematic discrepancy anymore !
(Vink et al.
2000)
Lamers et al. (1995)
Crowther et al. (2006)
Monte Carlo Mass-loss rates
 dM/dt increases by factor 3-5
(Vink et al. 1999)
The bi-stability Jump
HOT
COOL
Fe IV
Fe III
low dM/dt
high Vinf
high dM/dt
low Vinf
Low density
High density
Stars should pass the bistable limit
• During evolution from O  B
• LBVs on timescales of years
LBVs in the HRD
Smith, Vink & de Koter (2004)
The mass loss of LBVs
Models
Data
Stahl et al. (2001)
Vink & de Koter (2002)
Stars should pass the bistable limit
• During evolution from O  B
• LBVs on timescales of years
Implications for circumstellar medium (CSM)
Mass-loss rate
up ~ 2
wind velocity
down ~ 2
CSM density variations ~ 4
SN-CSM interaction  radio
Weiler et al. (2002)
Mass Loss Results from Radio SNe
OB star? WR?
SN 2001ig & 2003bg
2003bg
2001ig
Ryder et al. (2004)
Soderberg et al.
(2006)
Progenitors
• AGB star
• Binary WR system
• WR star
• LBV
Progenitors
• AGB star
• Binary WR system
• WR star
• LBV
Kotak & Vink (2006)
Assumptions in line-force models
• Stationary
• One fluid
• Spherical
Polarimetry – from disks
Depolarisation
Asphericity in LBV: HR CAR
(Davies, Oudmaijer & Vink 2005)
SURVEY: asphericity found in 50%
Variable polarization in AG CAR
(Davies, Oudmaijer & Vink 2005)
 RANDOM: CLUMPS!!
Assumptions in line-force models
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Stationary
One fluid
Spherical
Homogeneous, no clumps
Success of Monte Carlo at solar Z
• O-star Mass loss rates
• Prediction of the bi-stability jump
• Mass loss behaviour of LBVs like AG Car
 Monte Carlo mass-loss used in
stellar models in Galaxy
O star mass-loss Z-dependence
(Vink et al. 2001)
O star mass-loss Z-dependence
Kudritzki (2002) ---
Vink et al. (2001)
O star mass-loss Z-dependence
Which metals are important?
Vink et al. (2001)
solar Z
Fe
CNO
H,He
low Z
At lower Z :
Fe  CNO
WR stars produce Carbon !
Geneva models (Maeder & Meynet 1987)
WR stars produce Carbon !
Geneva models (Maeder & Meynet 1987)
Which element drives WR winds?
- C
 WR mass loss not Z(Fe)-dependent
- Fe  WR mass loss depends on Z host
Z-dependence of WR winds
WN
WC
Vink & de Koter (2005, A&A 442, 587)
Corollary of lower WR mass loss:
 less angular momentum loss
 favouring the collapse of WR stars to
produce GRBs
 Long-duration GRBs favoured at low Z
Conclusions
• Successful MC Models at solar Z
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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
• Wind Clumping
• Compute Mdot close to Eddington limit
Mass loss & Eddington Limit
~ Gamma^5
Vink (2006) - astro-ph/0511048
Future Work
• Solving momentum equation
• Wind Clumping
• Compute Mdot close to Eddington limit
• Compute Mdot at subsolar and Z = 0
From Scientific American
Non-consistent velocity law
WC8
Beta = 1
Wind momenta at low Z
Data (Mokiem)
Models (Vink)
Vink et al. (2001)
Mokiem et al. (2007)
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)
Advantages of our method
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Non-LTE
Unified treatment (no core-halo)
Monte Carlo line force at all radii
Multiple scatterings
 O stars at solar Z & low Z
LBV variability & WR as a function of Z
The bi-stability Jump
HOT
COOL
Fe IV
Fe III
low dM/dt
high V(inf)
dM/dt = 5 dM/dt HOT
V(inf) = ½ vinf HOT
Low density
High density = 10 HOT
The reason for the bi-stability jump
• Temperature drops
 Fe recombines from Fe IV to Fe III
 Line force increases
 dM/dt up
 density up
 V(inf) drops
 “Runaway”
Quantifying the effect of the velocity
law
Can we use our approach for WR
stars?
• Potential problems:
– Are these winds radiatively driven?
– Is Beta = 1 a good velocity law?
– Do we miss any relevant opacities?
– What about wind clumping?
B Supergiants Wind-Momenta
Vink, de Koter & Lamers (2000)
New Developments:
• Hot Iron Bump Fe X --- Fe XVI
• Graefener & Hamann (2005) can “drive”
a WC5 star self-consistently
 Use Monte Carlo approach for a
differential study of Mass loss versus Z
The bi-stability jump at B1
Lamers et al. (1995)
Pauldrach & Puls (1990)