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J/MNRAS/375/1220    BVI photometry of young stars in 10 clusters  (Mayne+, 2007)

Empirical isochrones and relative ages for young stars, and the radiative-convective gap. Mayne N.J., Naylor T., Littlefair S.P., Saunders E.S., Jeffries R.D. <Mon. Not. R. Astron. Soc., 375, 1220-1240 (2007)> =2007MNRAS.375.1220M
ADC_Keywords: Stars, pre-main sequence ; Photometry, UBVRI ; Clusters, open Keywords: techniques: photometric - catalogues - stars: evolution - stars: formation - Hertzsprung-Russell (HR) diagram - stars: pre-main-sequence Abstract: We have selected pre-main-sequence (PMS) stars in 12 groups of notional ages ranging from 1 to 35Myr, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour-magnitude diagrams. This allows us to identify clearly the gap between the radiative main sequence and the convective PMS (the RC gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than =15 Myr old. We also observe a reduction in absolute spreads about the sequences with age. Finally, the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC 6530 and IC 5146 (nominally 1Myr); next Cep OB3b, NGC 2362, Ori and NGC 2264 (nominally 3Myr); and finally Ori and IC 348 (nominally 45Myr). This suggests Cep OB3b is younger than previously thought, and IC 348 older. For IC 348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionizing radiation may be an important factor in the removal of discs in other clusters. Description: We present photometry in V, V-I and in some cases B-V for a range of star forming regions. NGC2547, NGC7160, NGC2264, Cepheus OB3b, Sigma Orionis, IC348 and h and chi Per. A full description of the data can be found at: File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file ngc2547.dat 136 141 NGC 2547 photometric catalog (tables 4-5) ngc7160.dat 136 31512 NGC 7160 photometric catalog (tables 6-7) ngc2264.dat 136 62276 NGC 2264 photometric catalog (tables 8-12) cepob3b.dat 136 36534 Cepheus OB3b photometric catalog (tables 13-18) sigori.dat 136 90390 sigma Ori photometric catalog (tables 19-21) ic348.dat 136 7507 IC 348 photometric catalog (tables 22-27) persei.dat 136 56482 h and chi Per photometric catalog (tables 28-29) samples.dat 149 29 Samples of membership criteria
Byte-by-byte Description of file: n*.dat c*.dat sigori.dat i*.dat p*.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Cluster Cluster name 11 I1 --- Cat [0/1]? 0 for Full photometric catalog 1 for All stars in FOV catalog 13- 26 A14 --- Sample Sample member code(s), in samples.dat 28- 33 F6.2 --- Field Field number.CCD number if available NNN.NN (1) 34- 38 I5 --- MNLSJ Star designation number from MNLSJ (2007) 40- 41 I2 h RAh Right ascension (J2000.0) (1) 43- 44 I2 min RAm Right ascension (J2000.0) (1) 46- 51 F6.3 s RAs Right ascension (J2000.0) (1) 53 A1 --- DE- Declination sign (J2000.0) (1) 54- 55 I2 deg DEd Declination (J2000.0) (1) 57- 58 I2 arcmin DEm Declination (J2000.0) (1) 60- 64 F5.2 arcsec DEs [0/60] Declination (J2000.0) (1) 66- 73 F8.3 pix Xpos X position 75- 82 F8.3 pix Ypos Y position 84- 89 F6.3 mag Vmag ?=99.999 Johnson V magnitude 91- 96 F6.3 mag e_Vmag ?=99.999 rms uncertainty on Vmag 98- 99 A2 --- q_Vmag Quality flag on Vmag (2) 101-107 F7.3 mag V-Ic ?=99.999 Cousins V-I colour index 109-114 F6.3 mag e_V-Ic ?=99.999 rms uncertainty on V-Ic 116-117 A2 --- q_V-Ic Quality flag on V-Ic (2) 119-125 F7.3 mag B-V ?=99.999 Johnson B-V colour index (3) 128-133 F6.3 mag e_B-V ?=99.999 rms uncertainty on B-V (3) 135-136 A2 --- q_B-V Quality flag on B-Vmag (2) (3)
Note (1) : in ngc2264.dat, data from sample No. 26 (proper motion members): - field number: 1.00 denotes a star from Walker (1956ApJS....2..365W) 2.00 denotes a star from Vasilevskis et al. (1965AJ.....70..797V) - Positions are from 2MASS (Cat. II/246) via matching of ID's through WEBDA. ( - There are no Xpos and Ypos (set to 0.000). Note (2): Quality flags are: O = O.K. N = Non-stellar H = Aperture photometry used E = Too close to CCD edge B = Background fit failed I = Ill-determined background P = Position fit failed S = Saturated E = Too close to edge F = Flagged pixel R = Uncalibrated region A = Absent input data M = Negative (minus) counts V = Variable C = Large relative transparency correction (cloudy) Note (3): For CepOB3b, B-V colour index unavailable.
Byte-by-byte Description of file: samples.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Code Sample number 4- 24 A21 --- Type Type of data 25-149 A125 --- Ref References
Acknowledgements: Nathan Mayne, N.J.Mayne(at)
(End) Patricia Vannier [CDS] 12-Apr-2007
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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