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Winds that Sail on Starlight Stan Owocki Bartol Research Institute University of Delaware Collaborators: – Asif Ud-Doula, U. Delaware – Vikram Dwarkadas,

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Presentation on theme: "Winds that Sail on Starlight Stan Owocki Bartol Research Institute University of Delaware Collaborators: – Asif Ud-Doula, U. Delaware – Vikram Dwarkadas,"— Presentation transcript:

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

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

3 STScI 11/07/01 Winds that Sail on Starlight 3 Pistol Nebula

4 STScI 11/07/01 Winds that Sail on Starlight 4 Eta Carinae

5 STScI 11/07/01 Winds that Sail on Starlight 5 P-Cygni Line Profiles

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

7 STScI 11/07/01 Winds that Sail on Starlight 7 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?? Light’s Momentum

8 STScI 11/07/01 Winds that Sail on Starlight 8 Free Electron Scattering Thompson Cross Section th e-e-  Th  = 2/3 barn= 0.66 x 10 -24 cm 2

9 STScI 11/07/01 Winds that Sail on Starlight 9 How big is electron scattering force vs. gravity?? Expressed through a star’s Eddington parameter  ~  g el g grav   e L 4  GMGMc Eddington Parameter For sun,  O ~ 2 x 10 -5 But for hot-stars with L~ 10 6 L O ; M=10-50 M O r  L 4  r 2 c Th  e GM 2 

10 STScI 11/07/01 Winds that Sail on Starlight 10 Q~  ~ 10 15 Hz * 10 -8 s ~ 10 7 Q ~ Z Q ~ 10 -4 10 7 ~ 10 3 Line Scattering: Bound Electron Resonance  lines ~Q  Th g lines ~10 3  g el L  L thin } if  lines ~10 3  el  1 for high Quality Line Resonance, cross section >> electron scattering

11 STScI 11/07/01 Winds that Sail on Starlight 11 Optically Thick Line-Absorption in an Accelerating Stellar Wind L sob For strong, optically thick lines:

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

13 STScI 11/07/01 Winds that Sail on Starlight 13 CAK model of steady-state wind inertiagravityCAK line-force Equation of motion:  < 1 CAK ensemble of thick & thin lines

14 STScI 11/07/01 Winds that Sail on Starlight 14 CAK steady wind solution Mass loss rate Wind-Momentum Luminosity Law Velocity law

15 STScI 11/07/01 Winds that Sail on Starlight 15 Wolf-Rayet Winds “Momentum #”  =Mv  /(L/c) > 1 Requires multiple scattering. Need line spacing overlap v  /  v=  > 1

16 STScI 11/07/01 Winds that Sail on Starlight 16 Multi-line scattering “Bunched” line- distribution photon “leakage” “Effectively gray” line-distribution

17 STScI 11/07/01 Winds that Sail on Starlight 17 Inward-propagating Abbott waves ±vªe i(kr°!t) ° @v 0 i!±v= @g rad ±v 0 ¥Uik±v w=k=°U U= @g rad @v 0 ª g r v 0 ª vv 0 v 0 ªv @v @t =g r v r  g~  v’ Abbott speed

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

19 STScI 11/07/01 Winds that Sail on Starlight 19 Wind variations from base perturbations in density and brightness log(Density) Velocity Radius wind base perturbed by  ~ 50 radiative driving modulated by brightness variations Abbott-mode“kinks” velocity “plateaus” shock compression

20 STScI 11/07/01 Winds that Sail on Starlight 20 BW Vul: Observations vs. Model C IVModel line

21 STScI 11/07/01 Winds that Sail on Starlight 21 HD64760 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. ¥These may stem from large-scale surface structure that induces spiral wind variation analogous to solar Corotating Interaction Regions. Radiation hydrodynamics simulation of CIRs in a hot-star wind Rotational Modulation of Hot-Star Winds

22 STScI 11/07/01 Winds that Sail on Starlight 22 WR6 - wind modulation model m=4 dynamical model NIV in WR 6

23 STScI 11/07/01 Winds that Sail on Starlight 23 Line-Driven Instability u=v/v th for < L sob :  g ~  u Instability with growth rate  ~ g/v th ~ v/L sob ~100 v/R => e 100 growth!

24 STScI 11/07/01 Winds that Sail on Starlight 24 Bridging law ±g ±v =≠ ikl 1+ l ±g=≠±v kl¿1 ±g=≠ l±v = U±v klø1 lºL ¥ v th dv=dr Abbott/Sobolev limit Instability limit

25 STScI 11/07/01 Winds that Sail on Starlight 25 Local vs. Nonlocal Line-Force Sobolev approximation Local Sobolev optical depth Nonlocal ray optical depth

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

27 STScI 11/07/01 Winds that Sail on Starlight 27 3-Ray Grid for 2D Nonlocal Rad-Hydro Diagram: N  = 9 ;  = 10 o Actual code: N  =157 ;  = 0.01 rad I-I- IoIo I+I+ g  ~ I - - I +

28 STScI 11/07/01 Winds that Sail on Starlight 28 2D Simulation of Co-rotating Interaction Regions local CAK model nonlocal smooth model nonlocal structured model c.  log(Density) b. a.

29 STScI 11/07/01 Winds that Sail on Starlight 29 WR Emission Line Variability WR 135WR 137WR 140

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

31 STScI 11/07/01 Winds that Sail on Starlight 31 Colliding Wind Momentum Balance Wind-wind balance Wind-radiation balance WR wind Symmetric or widely separated binaries Asymmetric (e.g.WR+O) close binaries O-star radiation O-star wind

32 STScI 11/07/01 Winds that Sail on Starlight 32 WR+O Colliding wind * WR Star O Star “Radiative Braking” Pure Hydro * WR Star O Star Radiation Hydro e.g., V444 Cygni

33 STScI 11/07/01 Winds that Sail on Starlight 33 Extended Evolution of Instability Structure t=430 ksec Time (ksec) 010203040 430 450 470 490 Height (R * ) log Density (g/cm3) 40 0 102030 430 450 470 490 Time (ksec) 010203040 Velocity (km/s) 010203040

34 STScI 11/07/01 Winds that Sail on Starlight 34 Ion Runaway Instability Chandrasekhar function:

35 STScI 11/07/01 Winds that Sail on Starlight 35 WR Wind Blobs Infer acceleration over extended scale:  R * ~ 20-50 R O g rad ~  L * /4  r 2 c Requires radially increasing effective opacity  ~  /m Possible from desaturation of optically thick blobs Yields  ~  ~ r 2 g rad ~ constant! Lepine & Moffat 1999

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

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

38 STScI 11/07/01 Winds that Sail on Starlight 38 Bipolar nebula from rotating hot-star wind without gravity darkening with gravity darkening

39 STScI 11/07/01 Winds that Sail on Starlight 39 Wind Compressed Disk Model Bjorkman & Cassinelli 1993

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

41 STScI 11/07/01 Winds that Sail on Starlight 41 Vector Line-Force dv n /dn Net poleward line force from: faster polar wind slower equatorial wind r Max[dv n /dn] (2) Pole-equator aymmetry in velocity gradient r Flux (1) Stellar oblateness => poleward tilt in radiative flux N

42 STScI 11/07/01 Winds that Sail on Starlight 42 Wind rotation spindown from azimuthal line-torque g  (10 3 cm/s 2 ) [V  (nrf) - V  (wcd)] *sin(  )*r/R eq (km/s) a. b. -10 -30 -50 -70 -90 -0.1 -0.3 -0.5 -0.7 -0.9 azimuthal line-force ang. mom. loss

43 STScI 11/07/01 Winds that Sail on Starlight 43 Azimuthal Line-Torque  V + <  V_ g  ~   V + -  V_ < 

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

45 STScI 11/07/01 Winds that Sail on Starlight 45 Accretion Disk Winds from BAL QSOs

46 STScI 11/07/01 Winds that Sail on Starlight 46 Line-Driven Ablation g lines ~ dv l /dl Net radiative Flux = 0, but g lines ~ dv l /dl > 0 !

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

48 STScI 11/07/01 Winds that Sail on Starlight 48 MHD simulation of line-driven wind Initialafter 2 days Zoom on final Zeta Puppis with B o =400 G

49 STScI 11/07/01 Winds that Sail on Starlight 49 MHD simulation of line-driven wind Zoom on density Density Y- Velocity -1000 v y (km/s) 1000

50 STScI 11/07/01 Winds that Sail on Starlight 50 Magnetic modulation of wind speed

51 STScI 11/07/01 Winds that Sail on Starlight 51 295 G ;  * = 1 Final state of ZPup isothermal models 1650 G ;  * = 32 930 G ;  * = 10 520 G ;  * = 3.2 165 G ;  * = 0.32 93 G ;  * = 0.1

52 STScI 11/07/01 Winds that Sail on Starlight 52 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 Sob << R * –leads to shocks, clumping, compressible turbulence –may explain X-rays Current work –effect of NRP, B-field on wind –application to BAL QSO/AGN disk winds –formation of Be disks –Super-Eddington Luminous Blue Variables

53 STScI 11/07/01 Winds that Sail on Starlight 53 Chandra Observations Z Pup Z Ori Cassinelli et al. 2001 Waldron et al. 2001

54 STScI 11/07/01 Winds that Sail on Starlight 54 Thin vs. Thick line-emission q=0 => f x =const. for r > R o   =1, 3, 5, 10 cf. Ignace & Gayley 2001 for  =0 case

55 STScI 11/07/01 Winds that Sail on Starlight 55 Opacity in a porous (“blobby”) medium ø b =∑Ω b l=∑m b =l 2 =∑πΩfL 3 2 =∑πΩfh; f¥m b =m h¥L 3 =l 2 Effect on R 1 of constant velocity expansion R c (  =1) _______ R 1 h 0.975 0.9 0.95 0.925 f=1 ∑ b º∑ ∑ 1°e °ø b ø b ∏

56 STScI 11/07/01 Winds that Sail on Starlight 56 Wind Magnetic Confinement Ratioofmagnetictokineticenergydensity: ¥(r)¥ B 2 =8º Ωv 2 =2 = B 2 r 2 _ Mv ¥¥ § (r=R § ) 2°2q (1°r=R § ) Ø forradial(monopole)Øeldq=2. WindmagneticconØnementnumber: ¥ § ¥ B 2 § R 2 § _ Mv 1 AlfvenicMachnumber: M A ¥ v v A = 1 p ¥ 22 ° =1:6 B 100 R 12 _ M 6 v 8 FordipoleØeld,q=; 3 ~ 300 G for ZPup B * ~ 150 G for  1 Ori C but for O-stars, to get  * ~ 1, need:for solar wind,  * ~ 150...

57 STScI 11/07/01 Winds that Sail on Starlight 57 Magnetic modulation of wind speed  * = 10  * = 1  * = 1/10

58 STScI 11/07/01 Winds that Sail on Starlight 58 Magnetic effects on solar coronal expansion 1991 Solar Eclipse Coronal streamers Coronal hole Closd loops Coronal hole Closd loops

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