J/A+A/325/167 Geneva photometry in NGC 6231 (Raboud+ 1997)
Geneva photometry in the young open cluster NGC 6231
Raboud D., Cramer N., Bernasconi P.A.
<Astron. Astrophys. 325, 167 (1997)>
=1997A&A...325..167R 1997A&A...325..167R
ADC_Keywords: Clusters, open ; Photometry, Geneva
Keywords: open clusters: individual: NGC 6231 - technique: photometry -
stars: formation - stars: pre-main sequence
Abstract:
We present photoelectric (127 stars) and CCD (168 stars) Geneva
photometry for the very young open cluster NGC 6231. We have searched
for new cluster members out to a distance of ∼13arcmin, extending the
Seggewiss area (∼8arcmin), and we found at least 64 new probable
members in this extended field. Differential reddening is clearly
measured across the cluster area. We determine the cluster distance
(1800pc) and age (3.8±0.6x106yr). The probable presence of
pre-main sequence stars and the consequence of this population on the
cluster formation history is analysed. We also found that the O8.5III
star S161 is a long term variable and we present its light curve
extending over more than 20 years. Finally we discuss the existence of
Ap stars in the cluster.
For a description of the Geneva photometric system, see e.g. GCPD/13
Objects:
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RA (2000) DE Designation(s)
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16 54.2 -41 48 NGC 6231 = OCl 997.0
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 120 128 Member stars in the center
table4.dat 121 44 Non-member stars
table5.dat 116 64 Member stars in the corona
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See also:
J/A+A/315/384 : Binarity among B-stars in NGC 6231 (Raboud, 1996)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Number Star number
7 I1 --- n_Number [1]? '1' indicates a CCD measurement
11- 13 A3 --- Class [nm? ] Membership (m=member, nm=non-member)
15- 19 F5.2 mag Vmag Apparent V magnitude
23- 27 F5.2 mag X X parameter in Geneva photometry
31- 35 F5.2 mag Y Y parameter in Geneva photometry
39- 43 F5.2 mag Z Z parameter in Geneva photometry
48- 51 F4.2 mag Ebv Colour excess
55- 59 F5.2 mag VMAG ? Absolute V magnitude
64- 67 F4.2 mag U-B U-B Geneva colour
71- 75 F5.2 mag B-V B-V Geneva colour
78- 84 F7.2 pix Xpos X coordinate centered on S289 (2)
87- 93 F7.2 pix Ypos Y coordinate centered on S289 (2)
97-116 A20 --- SpT Estimated photometric spectral type
(for table3 and 5) or
Rejection criteria (for table4)
118 I1 --- n_Class ? Remark on classification. See Note (3)
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Note (2): 1 pix = 1/16.4 arcmin
Note (3): Individual notes numbers as follows:
1 = The star could be considered as non-member, following the
proper motion values by Braes (1967BANS....2....1B 1967BANS....2....1B)
2 = Likely non-member, following Raboud (1996, Cat. J/A+A/315/384)
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Acknowledgements: Didier Raboud
References:
Braes L.L.E. 1967, Bull. Astr. Inst. Neth. Suppl., 2, 1 =1967BANS....2....1B 1967BANS....2....1B
Raboud D. 1996, A&A, 315, 384 =1996A&A...315..384R 1996A&A...315..384R, Cat. J/A+A/315/384
(End) Raboud [University of Lausanne] 07-Mar-1997