Massive star feedback – from the first stars to the present Jorick Vink (Keele University)
77
Massive star feedback – from the first stars to the present Jorick Vink (Keele University)
-
Upload
cameron-chandler -
Category
Documents
-
view
213 -
download
0
Transcript of 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)
• 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
OB[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)
• But……
Woosley (1993)
Progenitor for Collapsar model
• Rapidly rotating
• Hydrogen-free star (Wolf-Rayet star)
• But……
Stars have winds…
Woosley (1993)
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
The First Stars
Credit: V. Bromm
The Final products of Pop III stars
(Heger et al. 2003)
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 (Z, L, M, Teff)
STAR Fe
Lucy & Solomon (1970)Castor, Abbott & Klein (1975) = CAK
Wind
Radiation-driven wind by Lines
dM/dt = f (Z, L, M, Teff)
Abbott & Lucy (1985)
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
Fe IV
low dM/dt
high Vinf
Low density
COOL
Fe III
high dM/dt
low Vinf
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
Stahl et al. (2001) Vink & de Koter (2002)
Data
Models
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 ~ 2CSM density variations ~ 4
SN-CSM interaction radio
Weiler et al. (2002)
Mass Loss Results from Radio SNe
OB star? WR?
SN 2001ig & 2003bg
Soderberg et al. (2006)
2003bg
2001ig
Ryder et al. (2004)
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
• 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?
At lower Z : Fe CNO
solar Z
low Z
Fe
CNOH,He
Vink et al. (2001)
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
Vink & de Koter (2005, A&A 442, 587)
WC
WN
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
• 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
Vink (2006) - astro-ph/0511048
~ Gamma^5
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
Beta = 1
WC8
Wind momenta at low Z
Vink et al. (2001) Mokiem et al. (2007)
Models (Vink)
Data (Mokiem)
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
• 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
Fe IV
low dM/dt
high V(inf)
Low density
COOL
Fe III
dM/dt = 5 dM/dt HOT
V(inf) = ½ vinf HOT
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)
