Winds that Sail on Starlight Stan Owocki Bartol

Winds that Sail on Starlight Stan Owocki Bartol Research Institute University of Delaware Collaborators: STSc. I 11/07/01 – Asif Ud-Doula, U. Delaware – Vikram Dwarkadas, U. Del. – Ken Gayley, U. Iowa – David Cohen, Swarthmore – Steve Cranmer, Cf. A – Joachim Puls, U. Munich – Luc Dessart, Utrecht – Mark Runacres, U. Brussels Winds that Sail on Starlight

Henize 70: LMC Super. Bubble Wind-Blown Bubbles in ISM Some key scalings: WR wind bubble NGC 2359 STSc. I 11/07/01 Superbubble in the Large Magellanic Cloud Winds that Sail on Starlight 2

Pistol Nebula STSc. I 11/07/01 Winds that Sail on Starlight 3

Eta Carinae STSc. I 11/07/01 Winds that Sail on Starlight 4

P-Cygni Line Profiles STSc. I 11/07/01 Winds that Sail on Starlight 5

Sailing vs. Radiative Driving • Early sails • CAK 1975 – symmetric form – sail mainly with wind – 1 D spherically symmetric – radially driven outflow • Line-driving ca. 2000 • Modern sails – asymmetric form + keel – can tack against wind – unstable to “keeling over” – asymmetric velocity gradient – force not || flux • spindown & disk inhibition • ablation & disk winds – radiative braking – small-scale instability STSc. I 11/07/01 Winds that Sail on Starlight 6

Light’s Momentum • Light transports energy (& information) • But it also has momentum, p=E/c • Usually neglected, because c is so high • But becomes significant for very bright objects, e. g. Lasers, Hot stars, QSO/AGN’s • Key question: how big is force vs. gravity? ? STSc. I 11/07/01 Winds that Sail on Starlight 7

Free Electron Scattering e Thompson Cross Section th s. Th = 2/3 barn= 0. 66 x 10 -24 cm 2 STSc. I 11/07/01 Winds that Sail on Starlight 8

Eddington Parameter • How big is electron scattering force vs. gravity? ? • Expressed through a star’s Eddington parameter L s. Th gel 4 p r 2 c m e ke L Gº = = ggrav 4 p. GMc GM 2 r • For sun, GO ~ 2 x 10 -5 • But for hot-stars with 6 L�L~ 10 MO O ; M=10 -50 G<1 ~ STSc. I 11/07/01 Winds that Sail on Starlight 9

Line Scattering: Bound Electron Resonance for high Quality Line Resonance, cross section >> electron scattering Q~ n t ~ 1015 Hz * 10 -8 s ~ 107 Q ~ Z Q ~ 10 -4 107 ~ 103� s lines ~Q´ s Th glines ~103 ´ g el G 3 ´ G >> 1 ~ 10 lines el STSc. I 11/07/01 Winds that Sail on Starlight } if L = Lthin 10

Optically Thick Line-Absorption in an Accelerating Stellar Wind For strong, optically thick lines: STSc. I 11/07/01 Lsob Winds that Sail on Starlight 11

CAK model of steady-state wind inertia gravity CAK line-accel. 0<a<1 CAK ensemble of thick & thin lines Equation of motion: . * fix M to make line-accel. order gravity * Mass loss rate Velocity law Wind-Momentum Luminosity Law STSc. I 11/07/01 Winds that Sail on Starlight 12

Wolf-Rayet Winds. • “Momentum #” h=Mv¥/(L/c) > 1 • Requires multiple scattering Need line spacing overlap v¥ /Dv= h > 1 STSc. I 11/07/01 Winds that Sail on Starlight 15

Inward-propagating Abbott waves @v = gr ad @t ±v ª ei ( k r ° @gr ad 0 ° i! ±v = ±v @v 0 ¥ U ik ±v ! t) w=k = ° U dg~ dv’ v Abbott speed @gr ad U = @v 0 gr ad vv 0 ª ª 0 0 ª v v v STSc. I 11/07/01 r Winds that Sail on Starlight 17

Pulsation-induced wind variability Abbott-mode“kinks” Velocity velocity “plateaus” radiative driving modulated by brightness variations Radius shock compression STSc. I 11/07/01 Winds that Sail on Starlight 18

BW Vul: Observations vs. Model C IV STSc. I 11/07/01 Model line Winds that Sail on Starlight 20

Rotational Modulation of Hot-Star Winds HD 64760 Monitored during IUE “Mega” Campaign ¥Monitoring campaigns of P-Cygni lines formed in hot-star winds also often show modulation at periods comparable to the stellar rotation period. STSc. I 11/07/01 Radiation hydrodynamics simulation of CIRs in a hot-star wind ¥These may stem from large-scale surface structure that induces spiral wind variation analogous to solar Corotating Interaction Regions. Winds that Sail on Starlight 21

Line-Driven Instability u=v/vth for l < Lsob: dg ~ du STSc. I 11/07/01 Instability with growth rate W ~ g/vth ~ v/Lsob ~100 v/R => e 100 growth! Winds that Sail on Starlight 23

Time snapshot of wind instability simulation CAK Velocity Density STSc. I 11/07/01 Winds that Sail on Starlight 26

WR Star Emission Profile Variability WR 140 Lepine & Moffat 1999 STSc. I 11/07/01 model Dessart & Owocki 2002 Winds that Sail on Starlight 30

WR+O Colliding wind Pure Hydro e. g. , V 444 Cygni O Star “Radiative Braking” Radiation Hydro O Star STSc. I 11/07/01 *WR Star Winds that Sail on Starlight *WR Star 32

Gravity Darkening increasing stellar rotation fast dense wind slower wind STSc. I 11/07/01 slower wind Winds that Sail on Starlight 36

Formation of Prolate Nebulae W-limit Gravity darkening Langer et al. 1999: Fast spherical wind into slow, dense equatorial flow STSc. I 11/07/01 Dwarkadas et al. 2001 Prolate fast wind into spherical medium Winds that Sail on Starlight 37

Wind Compressed Disk Simulations Vrot (km/s) = 200 250 300 350 400 450 radial forces only WCD Inhibition by non-radial line-forces STSc. I 11/07/01 Winds that Sail on Starlight 40

Vector Line-Force dvn/dn Net poleward line force from: vn / faster polar wind x[d r dn] (2) Pole-equator aymmetry in velocity gradient r Ma N Flu x (1) Stellar oblateness => poleward tilt in radiative flux slower equatorial wind STSc. I 11/07/01 Winds that Sail on Starlight 41

Wind rotation spindown from azimuthal line-torque azimuthal a. line-force -0. 9 -90 -0. 7 -70 -0. 5 -50 -0. 3 -30 -0. 1 -10 g f (10 3 cm/s 2 ) STSc. I 11/07/01 ang. mom. b. loss [V (nrf) - V (wcd)] f f *sin( q )*r/R eq Winds that Sail on Starlight (km/s) 42

Azimuthal Line-Torque DV+ < DV_ gf ~ DV+ - DV_ < 0 STSc. I 11/07/01 Winds that Sail on Starlight 43

Line-Force in Keplerian Disk STSc. I 11/07/01 Winds that Sail on Starlight 44

Accretion Disk Winds from BAL QSOs STSc. I 11/07/01 Winds that Sail on Starlight 45

Line-Driven Ablation Net radiative Flux = 0, but glines ~ dvl/dl > 0 ! es v d ~ /d l l g lin STSc. I 11/07/01 Winds that Sail on Starlight 46

Be disk formation by RDOME (Radiatively Driven Orbital Mass Ejection) STSc. I 11/07/01 Winds that Sail on Starlight 47

MHD simulation of line-driven wind Density Y- Velocity -1000 STSc. I 11/07/01 vy (km/s) Zoom on density 1000 Winds that Sail on Starlight 49

Final state of ZPup isothermal models 93 G ; h* = 0. 1 520 G ; h* = 3. 2 STSc. I 11/07/01 165 G ; h* = 0. 32 930 G ; h* = 10 Winds that Sail on Starlight 295 G ; h* = 1 1650 G ; h* = 32 51

Summary • Lines efficient way for radiation to drive mass – force depends of l. o. s. velocity gradient – for non-spherical geometry, anisotropic opacity – can get spindown, ablation, WCD inhibition, radiative braking, disk winds • Line-driving very unstable for l < � << R* Sob L – leads to shocks, clumping, compressible turbulence – may explain X-rays • Current work – – STSc. I 11/07/01 effect of NRP, B-field on wind application to BAL QSO/AGN disk winds formation of Be disks Super-Eddington Luminous Blue Variables Winds that Sail on Starlight 52