Winds of Massive StarsWinds of Massive Starsin the Low Metallicity in the Low Metallicity

Environment of the SMC.Environment of the SMC.

Collaborators: Danny Lennon, Chris Evans (ING), Philip Dufton (QUB), Joachim Puls (USM)

Carrie Trundle

Tartu Aug. 2005

Tartu Aug. 2005

• Subset of 10 supergiants from Lennon (1997) – EMMI/NTT medium resolution spectra.

• Supplemented by high resolution echelle spectra of 7 B supergiants - UVES/VLT (2001).

• Stellar parameters and abundances of these B0-B3 Ia supergiants were analysed using FASTWIND* - [Trundle et al. 2004, A&A,417,217; Trundle & Lennon 2005, A&A, 434, 677] –

Observational Dataset of SMC B Supergiants

*Puls et al. 2005, A&A, 435, 669

Tartu Aug. 2005

• Mass-loss rates of massive stars are important constraints for stellar evolution calculations - affect stellar masses, rotational velocities and element yields.

“…we again stress that any comparison between observed and predicted rotation for large massesis really much more a test bearing on the mass-loss rates than a test of the internal coupling and evolution of rotation.” Meynet & Maeder 2005, A&A,429, 581

Mass-Loss: Observations and Theory

Early B stars Mid B stars

5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0

30

29

28

27

Log (L*/L)

Log

(M

dotV

R

1/2)

Kudritzki et al. 1999 – Unblanketed Galactic

Trundle et al. 2004,2005 – Blanketed SMC

Crowther et al. 2005 – Blanketed Galactic

Wind Momenta: SMC & Galactic Observations

Early B stars Mid B stars

5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0

30

29

28

27

Log (L*/L)

Log

(M

dotV

R

1/2)

Trundle et al. 2004,2005 – Blanketed SMC

Crowther et al. 2005 – Blanketed Galactic

- - Crowther et al. 2005 Blanketed Galactic

Wind Momenta: SMC & Galactic Observations

Tartu Aug. 2005

Wind Momenta: SMC & Galactic Observations

• In MW and SMC, early B supergiants have higher wind-momenta than mid B’s.

• The slopes of the linear regression fits to the Galactic and SMC objects are different for both the Early and Mid (Teff< 23kK) SMC B supergiants. With the SMC being steeper (i.e lower). As expected from theory (Puls et al. 2000).

• Over the luminosity range in common between the Early B’s in the MW & SMC the wind momenta differ by ~0.6-0.35 dex whilst the Mid B’s differ by 0.9 to 0.5dex – Although there is a large spread at a given point in the two datasets.

Early B stars Mid B stars

5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0

30

29

28

27

Log (L*/L)

Log

(M

dotV

R

1/2)

Trundle et al. 2004,2005 – Blanketed SMC

Vink et al. 2001 – Theoretical predictions SMC

Wind Momenta: SMC Observations & Theory

Tartu Aug. 2005

Wind Momenta: SMC Observations & Theory

• Comparing the theoretical predictions of Vink et al. 2001 to our observations in the SMC :– Slopes are steeper by theory than observed for the early B

supergiants whilst they agree well for the mid B’s.

– In the Early B’s there is a difference between the wind-momenta but better agreement maybe obtained by considering clumping.

– Large discrepancy is seen between the observed and theoretical wind momenta of Mid B supergiants which can only be exasperated by considering clumping.

– Theory predicts a jump to higher Mass-loss rates for Mid B stars, in comparison to the Early B’s. Opposite to observed effect.

Tartu Aug. 2005

What is next!

• Important to understand the discrepancy between observations and theory - the increase of mass-loss as predicted by Vink et al. when introduced into the evolutionary models causes a large decrease in M & vrot as the objects move from blue to red supergiants.

• Mass loss rates of B type supergiants in the LMC – FEROS data of 40 B0-B3 Ia supergiants. – These will hopefully provide a better comparison with the smc objects with better constrained distances reducing the scatter in the wind-momenta. (In collaboration with C. Evans & D. Lennon –ING, La Palma)

Tartu Aug. 2005

SPECTRA & THEORETICAL FITS FROM FASTWIND

Nor

mal

ised

Flu

x

Wavelength (Å) 6550 6560 6570 6580 4060 4080 4100 4120 4140

1.1

1

.91.1

1

0.9

0.8

0.71.1

1

0.9

0.8

0.72

1.6

1.2

0.8

AV215 BN0Ia

AV104 B0.5Ia

AV216 B1III

AV78 B1Ia

O I

I

Si I

V

H I

Si

IV

H

e I

He

I

Trundle, Lennon,Puls & Dufton, 2004, A&A, 417, 217

Tartu Aug. 2005

Star ID Sp. Typ Teff Log g Mdot V Log sm

AV215 BN0 Ia 27000 2.90 1.35 1400 1.4 28.81

AV420 B0.5 Ia 27000 3.05 0.34 1310 1.0 28.11

AV104 B0.5 Ia 27500 3.10 0.40 1340 1.0 28.18

AV242 B1 Ia 25000 2.85 0.84 950 2.0 28.48

AV264 B1 Ia 22500 2.55 0.29 600 2.5 27.81

AV78 B1Ia+ 21500 2.40 2.29 450 3.0 28.76

Sk191 B1.5 Ia 22500 2.55 0.68 425 2.0 28.11

AV96 B1.5 Ia 22000 2.55 0.24 850 3.0 27.87

AV210 B1.5 Ia 20500 2.40 0.20 750 3.0 27.52

AV18 B2 Ia 19000 2.30 0.23 325 3.0 27.66

AV373 B2 Ia 19000 2.30 0.16 390 3.0 27.42

AV10 B2.5 Ia 17000 2.20 0.15 380 3.0 27.39

AV56 B2.5 Ia 16500 2.05 0.51 420 2.0 28.12

AV443 B2.5 Ia 16500 1.95 0.45 340 2.0 27.97

AV151 B2.5 Ia 16000 2.10 0.16 370 3.0 27.45

AV362 B3 Ia 14000 1.70 0.80 270 1.0 28.12

AV 22 B3 Ia 14500 1.90 0.23 280 1.0 27.47

Tartu Aug. 2005

Overview

• Introduce the dataset of SMC B supergiants and their mass-loss rates.

• Compare with Galactic B supergiants • Kudritzki et al. 1999• Crowther, Lennon & Walborn 2005

• Compare with theoretical predictions •Vink et al. 2000, 2001

Tartu Aug. 2005

Log

(L

/L)

Log (TEFF)

4.6 4.4 4.2 4.0 3.8 3.6

6.0

5.5

5.0

4.5

SMC B Supergiants

Early B (> B1.5)

Mid B (< B1.5)

Maeder & Meynet, 2001, A&A, 373,555

Non-rotating

Rotating

Meynet & Maeder, 2005, A&A, 429,581

Rotating

SMC HR- Diagram : Log (L/L) v’s TEFF