J/AJ/120/333 UBVRI and Hα in NGC 6530 (Sung+, 2000)
UBVRI and Hα photometry of the young open cluster NGC 6530.
Sung H., Chun M.-Y., Bessell M.S.
<Astron. J. 120, 333 (2000)>
=2000AJ....120..333S 2000AJ....120..333S
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, UBVRI ;
Photometry, H-alpha ;
Keywords: color-magnitude diagrams -
open clusters and associations: individual (NGC 6530) -
stars: early-type - stars: pre-main-sequence
Abstract:
New UBVRI and Hα photometry has been obtained for the young open
cluster NGC 6530 located 10' east of the Lagoon Nebula (M8). We found
37 pre-main-sequence (PMS) stars with Hα emission and nine PMS
candidates using the R-Hα color, a measure of Hα emission.
From this new photometry we derived the cluster parameters
(V0-MV=11.25±0.1mag and E(B-V)=0.35mag), typical age (1.5Myr),
and an age spread of about 5Myr. We confirmed the presence of a small
amount of differential reddening across the cluster. We also verified
the abnormal reddening law for the cluster, especially for a heavily
embedded O7 V star, Herschel 36. Comparisons were made for several PMS
evolution models with regard to the resulting age distribution and the
initial mass function.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 143 887 Photometric data
table3.dat 113 37 PMS stars with Hα emission
table4.dat 114 9 PMS candidates with weak Hα emission
table5.dat 71 29 PMS stars and candidates from HST data
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See also:
J/AJ/116/1801 : IC 4996 CCD photometry (Delgado+, 1998)
J/A+AS/123/63 : NGC 6530 multiwavelength photometry (van den Ancker+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- SCB [1/887]+ Running identification number in
NGC 6530 (Cl* NGC 6530 SCB NNNN in Simbad)
5- 6 I2 h RAh Right Ascension (J2000)
8- 9 I2 min RAm Right Ascension (J2000)
11- 14 F4.1 s RAs Right Ascension (J2000)
16 A1 --- DE- Declination (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 26 F4.1 arcsec DEs Declination (J2000)
28 I1 --- Tab [3-4]? Table number if object in tables 3 or 4
30- 35 F6.3 mag Vmag The weighted mean V band magnitude
37- 42 F6.3 mag V-I The weighted mean V-I color
44- 49 F6.3 mag B-V The weighted mean B-V color
51- 56 F6.3 mag U-B The weighted mean U-B color
58- 63 F6.3 mag R-Ha ? The weighted mean (R-Hα filter) color
66- 70 F5.3 mag e_Vmag Uncertainty in Vmag
72- 76 F5.3 mag e_V-I Uncertainty in V-I
78- 82 F5.3 mag e_B-V Uncertainty in B-V
84- 88 F5.3 mag e_U-B Uncertainty in U-B
90- 94 F5.3 mag e_R-Ha ? Uncertainty in R-Ha
97- 98 I2 --- o_Vmag Number of observations for Vmag
100-101 I2 --- o_V-I Number of observations for V-I
103-104 I2 --- o_B-V Number of observations for B-V
106-107 I2 --- o_U-B Number of observations for U-B
109-110 I2 --- o_R-Ha Number of observations for R-Ha
112-114 I3 --- Walker ? The Walker (1957ApJ...125..636W 1957ApJ...125..636W)
identification number (NGC 6530 NNN in Simbad)
115 A1 --- f_Walker Duplicity or uncertainty (?) flag for Walker
117-120 F4.2 --- Prob [0,1]? Proper motion membership probability (1)
122-128 A7 --- SpType ? Spectral type and luminosity class (2)
130-144 A15 --- Remark Further remarks (2)
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Note (1): Membership probability by van Altena & Jones (1972A&A....20..425V 1972A&A....20..425V).
Note (2): Spectral types are mostly from Hiltner et al. (1965ApJ...141..183H 1965ApJ...141..183H)
except for Herschel36 which is from Woolf (1961PASP...73..206W 1961PASP...73..206W).
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Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- SCB Sequential number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 15 F4.1 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 25 I2 arcsec DEs Declination (J2000)
27- 32 F6.3 mag Vmag V magnitude
34- 38 F5.3 mag V-I V-I colour index
40- 44 F5.3 mag B-V B-V colour index
46- 51 F6.3 mag U-B ? U-B colour index
53- 58 F6.3 mag R-Ha R-Hα colour index
60- 64 F5.3 mag e_Vmag rms uncertainty on Vmag
66- 70 F5.3 mag e_V-I rms uncertainty on V-I
72- 76 F5.3 mag e_B-V rms uncertainty on B-V
78- 82 F5.3 mag e_U-B ? rms uncertainty on U-B
84- 88 F5.3 mag e_R-Ha rms uncertainty on R-Ha
90 I1 --- o_Vmag Number of observation for Vmag
92 I1 --- o_V-I Number of observation for V-I
94 I1 --- o_B-V Number of observation for B-V
96 I1 --- o_U-B ? Number of observation for U-B
98 I1 --- o_R-Ha Number of observation for R-Ha
100-114 A15 --- Rem Remarks
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1 A1 --- PMS [SC] S: PMS stars, C: PMS candidates
3- 6 I4 --- SCB Sequential number
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 17 F4.1 s RAs Right ascension (J2000)
19 A1 --- DE- Declination sign (J2000)
20- 21 I2 deg DEd Declination (J2000)
23- 24 I2 arcmin DEm Declination (J2000)
26- 27 I2 arcsec DEs Declination (J2000)
29- 34 F6.3 mag Vmag V magnitude
36- 40 F5.3 mag V-I V-I colour index
42- 47 F6.3 mag Ha Hα magnitude
49- 53 F5.3 mag e_Vmag rms uncertainty on Vmag
55- 59 F5.3 mag e_V-I rms uncertainty on V-I
61- 65 F5.3 mag e_Ha rms uncertainty on Ha
67 I1 --- o_Vmag Number of observation for V
69 I1 --- o_V-I ? Number of observation for V-I
71 I1 --- o_Ha Number of observation for Hα
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History:
From AJ electronic version
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 29-Aug-2000