Massive star feedback from the first stars to
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 O B[e]](http://slidetodoc.com/presentation_image_h2/0d2f3c3856f573e32504c140ce4ed71c/image-7.jpg "Evolution of a Massive Star O B[e]")
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 ? • • 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 Lucy & Solomon (1970) Castor, Abbott & Klein (1975) = CAK Wind STAR d. M/dt = f (Z, L, M, Teff) Fe
Radiation-driven wind by Lines Abbott & Lucy (1985) d. M/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 d. M/dt increases by factor 3 -5 (Vink et al. 1999)
The bi-stability Jump HOT COOL Fe IV Fe III low d. M/dt high Vinf high d. M/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 2001 ig & 2003 bg 2001 ig 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 • • 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 • • 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 WC 8 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 • • 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 d. M/dt high V(inf) d. M/dt = 5 d. M/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 d. M/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 WC 5 star self-consistently Use Monte Carlo approach for a differential study of Mass loss versus Z
The bi-stability jump at B 1 Lamers et al. (1995) Pauldrach & Puls (1990)
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