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J/AJ/115/734        NGC 6231 UBVRI and Hα photometry (Sung+ 1998)

UBVRI and Hα Photometry of the young open cluster NGC 6231 Sung H., Bessell M.S., Lee S.-W. <Astron. J. 115, 734 (1998)> =1998AJ....115..734S
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, H-alpha Keywords: color-magnitude diagrams (H-R diagram) - clusters and associations: individual (NGC 6231) - stars: early-type Abstract: UBVRI and Hα CCD photometry has been obtained for the young open cluster NGC 6231. From the R-Hα color, a measure of the Hα emission, we find 12 pre-main-sequence (PMS) members and seven possible PMS members in the cluster. Applying recent stellar evolutionary tracks and PMS evolutionary tracks, we derive the age, age spread, and initial mass function of the cluster. The initial mass function of NGC 6231 is a Gaussian with a turnover at logm∼0.4 (m∼2.5M) and shows an abrupt decrease in the number of low-mass stars. Possible reasons for the suppression of low-mass star formation and star formation processes are discussed. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 16 54.2 -41 48 NGC 6231 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 112 852 Photometric data table4.dat 83 19 PMS (pre-main-sequence) stars and PMS candidates table5.dat 20 20 Mass function of NGC 6231
See also: J/A+A/325/167 : Geneva photometry in NGC 6231 (Raboud+ 1997) Table 1A: Atmospheric coefficients -------------------------------------------------------------------------------- Date k1,V k1,B k1,U k1,I -------------------------------------------------------------------------------- 1996 Aug 24 0.153±0.017 0.278±0.105 0.522±0.054 0.032±0.012 1996 Aug 25 0.140±0.011 0.297±0.034 0.519±0.011 0.050±0.005 1997 Feb 28 0.126±0.012 0.279±0.025 0.463±0.024 0.077±0.01922 Table 1B: Zero points -------------------------------------------------------------------------------- Date ξV ξ'V ξB ξU ξI -------------------------------------------------------------------------------- 24/08/96 -1.791±.018 -1.798±.016 -1.989±.023 -3.852±.018 -2.270±.016 25/08/96 -1.760±.018 -1.763±.019 -1.908±.011 -3.816±.019 -2.188±.022 28/02/97 -2.295±.014 -2.294±.016 -2.324±.014 -4.265±.025 -2.766±.022 Table 3: Comparison with photoelectric photometry -------------------------------------------------------------------------------- Authors {DELTA}V {DELTA}(B-V) {DETLA}(U-B) n ne -------------------------------------------------------------------------------- Bok et al. 1965 0.018±0.020 -0.010±0.031 -0.011±0.027 6 ( 5) Seggewiss 1968 -0.005±0.053 0.003±0.088 -0.009±0.112 19 ( 6) Schild et al. 1969 0.028±0.022 0.020±0.014 -0.006±0.025 12 ( 5) Garrison & Schild 1979 0.007±0.029 0.008±0.013 -0.029±0.011 16 ( 8) Heske & Wendker 1984, 1985 0.018±0.027 0.021±0.033 -0.001±0.055 14 ( 3) Perry et al. 1990 -0.006±0.035 0.006±0.008 -0.012±0.017 11 (13) Notes: n: Number of stars used ne: Number of stars excluded in the statistics Bok et al., 1965MNRAS.131..247B Seggewiss, 1968VeBon..79....1S Schild et al., 1969ApJ...156..609S Garrison & Schild, 1979AJ.....84.1020G Heske & Wendker, 1984A&AS...57..205H, 1985A&A...151..309H Perry et al., 1990A&AS...86..415P Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- ID Identification number (Cl* NGC 6231 SBL NNN in Simbad) 5- 11 F7.3 arcmin oRA Offset in right ascension (1) 13- 19 F7.3 arcmin oDE Offset in declination (1) 21 I1 --- o_Vmag Number of independent observations for Vmag 23- 28 F6.3 mag Vmag V magnitude 30- 34 F5.3 mag e_Vmag rms uncertainty on Vmag 36 I1 --- o_V-I ? Number of independent observations for V-I 38- 42 F5.3 mag V-I ? V-I colour index 44- 48 F5.3 mag e_V-I ? rms uncertainty on V-I 50 I1 --- o_B-V ? Number of independent observations for B-V 52- 56 F5.3 mag B-V ? B-V colour index 58- 62 F5.3 mag e_B-V ? rms uncertainty on B-V 64 I1 --- o_U-B ? Number of independent observations for U-B 66- 71 F6.3 mag U-B ? U-B colour index 73- 77 F5.3 mag e_U-B ? rms uncertainty on U-B 79 I1 --- o_R-Ha ? Number of independent observations for R-Ha 81- 86 F6.3 mag R-Ha ? R-Hα colour index 88- 92 F5.3 mag e_R-Ha ? rms uncertainty on R-Ha 94-103 A10 --- SpType MK Spectral type 106-112 A7 --- Name Other name (2)
Note (1): Positions relative to the adopted cluster center, RA=16h 54m 12s ; DE=-41° 50.5' (J2000). Note (2): In Simbad, Se NNN = NGC 6231 NNN SS NNN = Cl* NGC 6231 SS NNN HW NNN = Cl Trumpler 24 HW NNN
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1 A1 --- PMS [SC] S: PMS star, C: PMS candidate 3- 6 I4 --- ID Identification number (2) 7 A1 --- n_ID [a] a: PMS star 667 = Se 166 8- 13 F6.3 arcmin oRA Offset in right ascension (1) 15- 20 F6.3 arcmin oDE Offset in declination (1) 22- 27 F6.3 mag Vmag V magnitude 29- 33 F5.3 mag e_Vmag rms uncertainty on Vmag 35- 39 F5.3 mag V-I V-I colour index 41- 45 F5.3 mag e_V-I rms uncertainty on V-I 47- 51 F5.3 mag B-V B-V colour index 53- 57 F5.3 mag e_B-V rms uncertainty on B-V 59- 64 F6.3 mag U-B U-B colour index 66- 70 F5.3 mag e_U-B rms uncertainty on U-B 72- 77 F6.3 mag R-Ha R-Hα colour index 79- 83 F5.3 mag e_R-Ha rms uncertainty on R-Ha
Note (1): Positions relative to the adopted cluster center, RA=16h 54m 12s ; DE=-41° 50.5' (J2000). Note (2): ID numbers larger than 1000 are not in table2.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 4 F4.1 [solMass] log(M)l Lower value of log(m) interval 5 A1 --- --- [-] Dash 6- 8 F3.1 [solMass] log(M)u Upper value of log(m) interval 10- 12 I3 --- Ntot Total number of stars 14 I1 --- NPMS ? Number of PMS included 16- 20 F5.3 [solMass/kpc2] log(IMF) log of Initial Mass Function (1)
Note (1): log(IMF) is the number of star born in unit logarithmic mass per unit area in kpc2.
History: * 04-Apr-1998: From AAS Server Acknowledgements: Hwankyung Sung , Michael Bessell and See-Woo Lee
(End) Patricia Bauer [CDS] 01-Apr-1998
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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