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J/A+A/457/265       The VLT-FLAMES Survey of Massive Stars   (Dufton+, 2006)

The VLT-FLAMES Survey of Massive Stars: Stellar parameters and rotational velocities in NGC 3293, NGC 4755 and NGC 6611. Dufton P.L., Smartt S.J., Lee J.K, Ryans R.S.I., Hunter I., Evans C.J., Herrero A., Trundle C., Lennon D.J., Irwin M.J., Kaufer A. <Astron. Astrophys. 457, 265 (2006)> =2006A&A...457..265D
ADC_Keywords: Milky Way ; Clusters, open ; Stars, OB; Stars, atmospheres ; Rotational velocities Keywords: star: early-type - stars: fundamental parameters - stars: rotation - Hertzsprung-Russell (HR) and C-M diagrams - stars: evolution Abstract: An analysis is presented of VLT-FLAMES spectroscopy for three Galactic clusters, NGC 3293, NGC 4755 and NGC 6611. Non-LTE model atmosphere calculations have been used to estimate effective temperatures (from either the helium spectrum or the silicon ionization equilibrium) and gravities (from the hydrogen spectrum). Projected rotational velocities have been deduced from the helium spectrum (for fast and moderate rotators) or the metal line spectrum (for slow rotators). The origin of the low gravity estimates for apparently near main sequence objects is discussed and is related to the stellar rotational velocity. The atmospheric parameters have been used to estimate cluster distances (which are generally in good agreement with previous determinations) and these have been used to estimate stellar luminosities and evolutionary masses. The observed Hertzsprung-Russell diagrams are compared with theoretical predictions and some discrepancies including differences in the main sequence luminosities are discussed. Cluster ages have been deduced and evidence for non-coeval star formation is found for all three of the clusters. Projected rotational velocities for targets in the older clusters, NGC 3293 and NGC 4755, have been found to be systematically larger than those for the field, confirming recent results in other similar age clusters. The distribution of projected rotational velocities are consistent with a Gaussian distribution of intrinsic rotational velocities. For the relatively unevolved targets in the older clusters, NGC 3293 and NGC 4755, the peak of the velocity distribution would be 250km/s with a full-width-half-maximum of approximately 180km/s. For NGC 6611, the sample size is relatively small but implies a lower mean rotational velocity. This may be evidence for the spin-down effect due to angular momentum loss through stellar winds, although our results are consistent with those found for very young high mass stars. For all three clusters we deduce present day mass functions with Gamma-values in the range of -1.5 to -1.8, which are similar to other young stellar clusters in the Milky Way. Description: Tables 7, 8 and 9 contain observational and atmospheric parameters, rotational velocities, luminosities and masses of objects in the Galactic clusters NGC 3293, NGC 4755 and NGC 6611 respectively. See Evans et al. (2005, Cat. J/A+A/437/467) for detail of the observations. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table7.dat 83 92 Details of NGC 3293 objects table8.dat 83 88 Details of NGC 4755 objects table9.dat 83 44 Details of NGC 6611 objects
See also: J/A+A/437/467 : VLT-FLAMES survey of massive stars (Evans+, 2005) Byte-by-byte Description of file: table7.dat table8.dat table9.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Star Name (1) 9 A1 --- f_Name [*] *: stars lie outside the criteria for cluster membership 11- 15 F5.2 mag Vmag V magnitude 17- 21 F5.2 --- B-V B-V colour index 23- 36 A14 --- SpType MK spectral type 38- 42 I5 K Teff ? Effective Temperature 44- 47 F4.2 [cm/s2] logg ? logarithmic surface gravity 48 A1 --- u_logg Uncertainty flag on logg (2) 50- 52 A3 --- Method Methodology (3) 54- 56 I3 km/s vsini Projected rotational velocity 57 A1 --- u_vsini Uncertainty flag on vsini (2) 59- 62 F4.2 mag E(B-V) ? E(B-V) reddening 64- 67 F4.2 [solLum] logL ? logarithmic luminosity 69- 72 F4.1 solMass Mass ?=- Mass 74- 76 I3 km/s RV ? Radial velocity 77 A1 --- u_RV Uncertainty flag on vsini (2) 79- 83 F5.2 arcmin Dist Radial distance from cluster center
Note (1): Stars, NNNN-NNN are identified in Simbad as Cl* NGC NNN ESL NNN. Note (2): A colon indicates additional uncertainty Note (3): The specific method used to determine the atmospheric parameters are designated as follows: He = from neutral helium and hydrogen equivalent widths He+ = from ionized helium Si = Si III/Si IV ionization equilibrium and hydrogen line profiles A = effective temperature adopted I = effective temperature interpolated
Acknowledgements: Ian Hunter, i.hunter(at)
(End) Patricia Vannier [CDS] 11-Jul-2006
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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