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J/ApJ/622/1052      byHα photometry of NGC 3766           (McSwain+, 2005)

A photometric method to search for Be stars in open clusters. McSwain M.V., Gies D.R. <Astrophys. J., 622, 1052-1057 (2005)> =2005ApJ...622.1052M
ADC_Keywords: Clusters, open ; Stars, Be ; Photometry, uvby ; Photometry, H-alpha Keywords: open clusters and associations: individual (NGC 3766) - stars: emission-line, Be - techniques: photometric Abstract: We describe a technique to identify Be stars in open clusters using Stroemgren b, y, and narrowband Hα photometry. We first identify the B-type stars of the cluster using a theoretical isochrone fit to the (b-y, y) color-magnitude diagram. The strongest Be stars are easily identified in a (b-y, y-Hα) color-color diagram, but those with weaker Hα emission (classified as possible Be star detections) may be confused with evolved or foreground stars. Here we present such photometry plus Hα spectroscopy of members of the cluster NGC 3766 to demonstrate the accuracy of our technique. Description: We made photometric observations of the cluster NGC 3766 on 2002 Apr 1 using the Cerro Tololo Inter-American Observatory (CTIO) 0.9m telescope with the SITe 2048 CCD. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 95 209 Photometry of NGC 3766
See also: J/A+AS/119/271 : Be stars uvbyβ photometry (Fabregat+, 1996) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Star identification number in NGC 3766 5- 6 I2 h RAh Hour of Right Ascension (J2000) 8- 9 I2 min RAm Minute of Right Ascension (J2000) 11- 15 F5.2 s RAs Second of Right Ascension (J2000) 17 A1 --- DE- Sign of the Declination (J2000) 18- 19 I2 deg DEd Degree of Declination (J2000) 21- 22 I2 arcmin DEm Arcminute of Declination (J2000) 24- 27 F4.1 arcsec DEs Arcsecond of Declination (J2000) 29- 34 F6.3 mag ymag Stromgren y band magnitude 36- 40 F5.3 mag e_ymag Error in ymag 42- 46 F5.3 mag b-y Stromgren (b-y) color index 48- 52 F5.3 mag e_b-y Error in b-y 54- 58 F5.3 mag y-Ha The (y-Hα) color index 60- 64 F5.3 mag e_y-Ha Error in y-Ha 66- 68 A3 --- Code Stellar type (1) 70- 73 I4 --- WEBDA ? The WEBDA database number (2) 75- 94 A20 --- ONames Other identifiers
Note (1): Stellar code, defined as follows: Be = Be stars (Be) Be? = possible Be star; B = B-type star; O = other star in the field. Note (2): Maintained by J.-C. Mermilliod and is available online at
History: * 13-Sep-2005: From electronic version of the journal * 06-Jan-2006: CPD -60 3134 modified into CPD -60 3131 in table1
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 13-Sep-2005
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