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

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

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Target fields

• Fields chosen to sample a range of Z and ages

Young clusters (lt5 Myr) Old clusters (10-20 Myr)
Milky Way NGC 6611 NGC 3293, 4755
LMC N11 (inc. LH 9/10) NGC 2004
SMC NGC 346 NGC 330
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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!

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Target fields

• Fields chosen to sample a range of Z and ages

Young clusters (lt5 Myr) Old clusters (10-20 Myr)
Milky Way NGC 6611 NGC 3293, 4755
LMC N11 (inc. LH 9/10) NGC 2004
SMC NGC 346 NGC 330
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Target fields

• Fields chosen to sample a range of Z and ages

Young clusters (lt5 Myr) Old clusters (10-20 Myr)
Milky Way NGC 6611 NGC 3293, 4755
LMC N11 (inc. LH 9/10) NGC 2004
SMC NGC 346 NGC 330
Evans et al. (2005)
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Target fields

• Fields chosen to sample a range of Z and ages

Young clusters (lt5 Myr) Old clusters (10-20 Myr)
Milky Way NGC 6611 NGC 3293, 4755
LMC N11 (inc. LH 9/10) NGC 2004
SMC NGC 346 NGC 330
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Observational information

• High resolution R20,000
• 800 stars observed over the 7 fields
• _at_ 6 ?-settings, coverage from 3850-4750,
  6400-6650 Å
• LMC/SMC fields observed 6 times at each ?-setting
• Obtained in service mode, often different
  observational epochs
• for each ?-setting
• for repeat observations at each ?-setting

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Observational information

• High resolution R20,000
• 800 stars observed over the 7 fields
• _at_ 6 ?-settings, coverage from 3850-4750,
  6400-6650 Å
• LMC/SMC fields observed 6 times at each ?-setting
• Obtained in service mode, often different
  observational epochs
• for each ?-setting
• for repeat observations at each ?-setting

V 15.29
O9.5 V
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Targets in NGC 346
V-band DSS
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Targets in NGC 346
ACS (HST/Nota)
V-band DSS
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Targets in N11
NIR (from R. Barba)
V-band DSS
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Targets in N11
LH 10
LH 9
NIR (from R. Barba)
V-band DSS
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Census of young MC clusters
Field O Blt5 B5 Be AFG Total
N11 43 67 0 10 4 124
NGC 346 19 57 2 27 11 124
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Census of young MC clusters
Field O Blt5 B5 Be AFG Total
N11 43 67 0 10 4 124
NGC 346 19 57 2 27 11 124

• Incidence of Be-stars
• there is a selection effects for the Be-stars,
  one cannot simply take the above numbers at face
  value!

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Be-type spectra in NGC346
Ha
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Census of young MC clusters
Field O Blt5 B5 Be AFG Total
N11 43 67 0 10 4 124
NGC 346 19 57 2 27 11 124

• 62 O-type stars, half of them previously unknown
• Analysis now underway in Amsterdam
  
• more in Alex de Koters talk later
  today

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New O2-type star
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New O2-type star

• O2-2.5 III(f)
• Still small number statistics at earlier than O3
  (10 stars)

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N11 field
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N11 field
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N11 field
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N11 field
O2 star
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Binary detection

• Service observations _at_ 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
  ?-setting
• accurate to 5 km/s, which will no doubt
  find further binaries

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Binaries in the young MC clusters
Field O Blt5 Be Total
N11 43 67 10 120
NGC 346 19 57 27 103
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Binaries in the young MC clusters
Field O Blt5 Be Total
N11 Binaries 43 20 67 20 10 4 120 44
NGC 346 Binaries 19 4 57 18 27 5 103 27

• Note that these numbers do not include those
  found from cross-correlation methods expect
  them to go up slightly

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Binaries in the young MC clusters
Field O Blt5 Be Total
N11 Binaries 43 20 67 20 10 4 120 44
NGC 346 Binaries 19 4 57 18 27 5 103 27
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• Note that these numbers do not include those
  found from cross-correlation methods expect
  them to go up slightly

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Binaries in the young MC clusters
Field O Blt5 Be Total
N11 Binaries 43 20 67 20 10 4 110 40
NGC 346 Binaries 19 4 57 18 27 5 76 22
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• Note that these numbers do not include those
  found from cross-correlation methods expect
  them to go up slightly

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Binary detection time sampling
N11
57 days
84 days
NGC 346
Julian Date
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Binaries in the young MC clusters
Field O Blt5 Be Total
N11 Binaries 43 20 67 20 10 4 110 40
NGC 346 Binaries 19 4 57 18 27 5 76 22
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• Firm lower limits on binary fraction, to then
  compare with different star formation scenarios
  (eg Bally Zinnecker, 2005)

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