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Winds of Massive Stars in the Low Metallicity Environment of the SMC.

Winds of Massive Stars in the Low Metallicity Environment of the SMC. Carrie Trundle. Collaborators: Danny Lennon, Chris Evans (ING), Philip Dufton (QUB), Joachim Puls (USM). Tartu Aug. 2005. Observational Dataset of SMC B Supergiants.

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Winds of Massive Stars in the Low Metallicity Environment of the SMC.

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  1. Winds of Massive Stars in the Low Metallicity Environment of the SMC. Carrie Trundle Collaborators: Danny Lennon, Chris Evans (ING), Philip Dufton (QUB), Joachim Puls (USM) Tartu Aug. 2005

  2. Observational Dataset of SMC B Supergiants • 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] – *Puls et al. 2005, A&A, 435, 669

  3. Mass-Loss: Observations and Theory • Mass-loss rates of massive stars are important constraints for stellar evolution calculations-affectstellarmasses,rotationalvelocitiesandelementyields. • “…we again stress that any comparison between • observed and predicted rotation for large masses • is 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

  4. Wind Momenta: SMC & Galactic Observations 30 29 28 27 Early B stars Mid B stars Log (MdotV R1/2) 5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0 Log (L*/L) Kudritzki et al. 1999 – Unblanketed Galactic Trundle et al. 2004,2005 – Blanketed SMC  Crowther et al. 2005 – Blanketed Galactic

  5. Wind Momenta: SMC & Galactic Observations 30 29 28 27 Early B stars Mid B stars Log (MdotV R1/2) 5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0 - - Crowther et al. 2005 Blanketed Galactic Log (L*/L) Trundle et al. 2004,2005 – Blanketed SMC  Crowther et al. 2005 – Blanketed Galactic

  6. 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. Wind Momenta: SMC & Galactic Observations

  7. Wind Momenta: SMC Observations & Theory 30 29 28 27 Early B stars Mid B stars Log (MdotV R1/2) 5.0 5.2 5.4 5.6 5.8 6.0 5.0 5.2 5.4 5.6 5.8 6.0 Log (L*/L) Trundle et al. 2004,2005 – Blanketed SMC Vink et al. 2001 – Theoretical predictions SMC

  8. 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. Wind Momenta: SMC Observations & Theory

  9. Important to understand the discrepancy between observations and theory - the increase of mass-lossaspredictedbyVinketal.whenintroducedintotheevolutionarymodelscausesalargedecreaseinM&vrotastheobjectsmovefrombluetoredsupergiants. 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,LaPalma) What is next!

  10. O II Si IV H I Si IV He I He I 1.1 1 .9 1.1 1 0.9 0.8 0.7 1.1 1 0.9 0.8 0.7 2 1.6 1.2 0.8 AV215 BN0Ia AV104 B0.5Ia Normalised Flux AV216 B1III AV78 B1Ia 6550 6560 6570 6580 4060 4080 4100 4120 4140 Wavelength (Å) Trundle, Lennon,Puls & Dufton, 2004, A&A, 417, 217 SPECTRA & THEORETICAL FITS FROM FASTWIND

  11. 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

  12. 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 Log (L/L) 4.6 4.4 4.2 4.0 3.8 3.6 Log (TEFF) SMC HR- Diagram : Log (L/L) v’s TEFF

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