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]

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 ~ 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 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 CNO H,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/ ~ 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)