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The VLT-FLAMES Survey of Massive Stars Chris Evans (ING, La Palma)

The VLT-FLAMES Survey of Massive Stars Chris Evans (ING, La Palma). Tartu – August 2005. Main collaborators. Steve Smartt, Philip Dufton, Ian Hunter (Belfast) Danny Lennon (ING) Carrie Trundle , Artemio Herrero (IAC) Alex de Koter , Rohied Mokiem (Amsterdam) Mike Irwin (Cambridge).

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The VLT-FLAMES Survey of Massive Stars Chris Evans (ING, La Palma)

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  1. The VLT-FLAMES Survey of Massive StarsChris Evans (ING, La Palma) Tartu – August 2005

  2. Main collaborators • Steve Smartt, Philip Dufton, Ian Hunter (Belfast) • Danny Lennon (ING) • Carrie Trundle, Artemio Herrero (IAC) • Alex de Koter, Rohied Mokiem (Amsterdam) • Mike Irwin (Cambridge)

  3. FLAMES survey of massive stars • ESO Large Programme (PI: S. Smartt) • 112hrs on the VLT with FLAMES • FLAMES has 137 fibres which ‘feed’ the Giraffe spectrograph

  4. Target fields Fields chosen to sample a range of Z and ages:

  5. Some of our motivations • Obtain CNO abundances for a large, homogenous OB sample • Determine vsini distributions, evidence for Z-dependence? • Armed with vsini, explore CNO cf. evolutionary models • Tests of the Z-dependence of O star mass-loss rates • Un-planned, but interesting: Binary detection!

  6. Target fields Fields chosen to sample a range of Z and ages:

  7. Target fields Fields chosen to sample a range of Z and ages: Evans et al. (2005)

  8. Target fields Fields chosen to sample a range of Z and ages:

  9. Observational information • High resolution: R~20,000 • 800 stars observed over the 7 fields: • @ 6 λ-settings, coverage from 3850-4750, 6400-6650 Å • LMC/SMC fields observed 6 times at eachλ-setting • Obtained in service mode, often different observational epochs • for each λ-setting • for repeat observations at each λ-setting

  10. Observational information • High resolution: R~20,000 • 800 stars observed over the 7 fields: • @ 6 λ-settings, coverage from 3850-4750, 6400-6650 Å • LMC/SMC fields observed 6 times at eachλ-setting • Obtained in service mode, often different observational epochs: • for each λ-setting • for repeat observations at each λ-setting V = 15.29 O9.5 V

  11. Targets in NGC 346 V-band DSS

  12. Targets in NGC 346 ACS (HST/Nota) V-band DSS

  13. Targets in N11 NIR (from R. Barba) V-band DSS

  14. Targets in N11 LH 10 LH 9 NIR (from R. Barba) V-band DSS

  15. Census of young MC clusters

  16. Census of young MC clusters • Incidence of Be-stars: • there is a selection effects for the Be-stars, one cannot simply take the above numbers at face value!

  17. Be-type spectra in NGC346 Hα

  18. Census of young MC clusters • 62 O-type stars, ~half of them previously unknown • Analysis now underway in Amsterdam [more in Alex de Koter’s talk later today]

  19. New O2-type star

  20. New O2-type star • O2-2.5 III(f*) • Still small number statistics at earlier than O3 (~10 stars)

  21. N11 field

  22. N11 field

  23. N11 field

  24. N11 field O2 star

  25. Binary detection • Service observations @ multiple epochs » checks for binarity • Single/double-lined binaries found from simple methods: • from visual inspection when classifying the spectra • from radial velocity measurements of the H, He & Si lines [accurate to ~10 km/s] • More sophisticated methods now being used to cross-correlate the individual spectra at each λ-setting [accurate to ~5 km/s, which will no doubt find further binaries]

  26. Binaries in the young MC clusters

  27. Binaries in the young MC clusters • Note that these numbers do not include those found from cross-correlation methods – expect them to go up slightly

  28. Binaries in the young MC clusters 37% 26% • Note that these numbers do not include those found from cross-correlation methods – expect them to go up slightly

  29. Binaries in the young MC clusters 36% 29% • Note that these numbers do not include those found from cross-correlation methods – expect them to go up slightly

  30. Binary detection: time sampling N11 57 days 84 days NGC 346 Julian Date

  31. Binaries in the young MC clusters 36% 29% • Firm lower limits on binary fraction, to then compare with different star formation scenarios (eg Bally & Zinnecker, 2005)

  32. N abundances in B stars in NGC 346 Provisional results from TLUSTY analysis, (Ian Hunter, Belfast)

  33. N abundances in B stars in NGC 346 Binaries Provisional results from TLUSTY analysis, (Ian Hunter, Belfast)

  34. Summary • Lots of interesting objects in these young clusters! • Overview paper of LMC/SMC data, binary detection, radial velocities, etc: Evans et al., in prep. • Parallel studies: • LMC/SMC O-star analysis: Amsterdam • Galactic vsini paper: Belfast • Analysis of narrow-lined stars: Ian Hunter (Belfast) • Analysis of O stars in NGC 6611: Herrero/Villamariz (IAC)

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