J/A+A/376/144 BV(RI)CHα photometry of NGC 663 (Pigulski+, 2001)
The young open cluster NGC 663 and its Be stars.
Pigulski A., Kopacki G., Kolaczkowski Z.
<Astron. Astrophys. 376, 144 (2001)>
=2001A&A...376..144P 2001A&A...376..144P
ADC_Keywords: Clusters, open ; Stars, Be ; Photometry, UBVRI ;
Photometry, Cousins ; Photometry, H-alpha
Keywords: stars: emission-line, Be -
open clusters and associations: individual: NGC 663
Abstract:
We present new BV(RI)CHα photometry of the young open cluster
NGC 663. The Hα photometry is complete down to magnitude
RC=15.4, corresponding to spectral type A5 for the cluster members.
This allows detection of mild and strong Hα emission in all
B-type stars in the cluster. In addition to the 22 Be stars known in
the observed field of NGC 663, we discovered four new faint stars of
this type. We find that Be stars in NGC 663 cover the whole range of
the B spectral type. They are, however, most populous among stars with
spectral types falling in the range between B0 and B3, where their
fraction amounts to 31±8%. Among B-type stars later than B3, Be
stars are much less abundant: only 7 out of 101 observed stars, that
is, 7±3%, were detected. About 70% of the observed Be stars in NGC
663 show detectable variations of light. In the time interval covered
by our observations, the ranges of the largest variations reach 0.4mag
in the IC band. By means of the isochrone fitting, we derived the
cluster distance of 2.1kpc, age of 20-25Myr, and the mean colour
excess E(R-I)C=0.54mag, with a ∼0.1mag scatter due to differential
reddening.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 171 1253 BV(RI)c and Hα photometry, coordinates and
cross-identifications for observed stars
table3.dat 31 38 Epoch Hα photometry of the observed Be stars
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 pix Xpos X coordinate of a star in Fig.2, see Note (1)
8- 15 F8.1 pix Ypos Y coordinate of a star in Fig.2
17- 18 I2 h RAh Right Ascension (epoch J2000.0)
20- 21 I2 min RAm Right Ascension (epoch J2000.0)
23- 27 F5.2 s RAs Right Ascension (epoch J2000.0)
29 A1 --- DE- Declination sign (epoch J2000.0)
30- 31 I2 deg DEd Declination (epoch J2000.0)
33- 34 I2 arcmin DEm Declination (epoch J2000.0)
36- 39 F4.1 arcsec DEs Declination (epoch J2000.0)
42 I1 --- o_Bmag ? Number of B-filer measurements
44- 45 I2 --- o_Vmag ? Number of V-filer measurements
47- 48 I2 --- o_Rcmag ? Number of Rc-filer measurements
50- 51 I2 --- o_Icmag ? Number of Ic-filer measurements
53- 58 F6.3 mag Bmag ? B magnitude
60- 65 F6.3 mag Vmag ? V magnitude
67- 72 F6.3 mag Rcmag ? Cousins R magnitude
74- 79 F6.3 mag Icmag ? Cousins I magnitude
81- 84 F4.3 mag e_Bmag ? Error of B magnitude
86- 89 F4.3 mag e_Vmag ? Error of V magnitude
91- 94 F4.3 mag e_Rcmag ? Error of Rc magnitude
96- 99 F4.3 mag e_Icmag ? Error of Ic magnitude
101 I1 --- o_alphan Number of Halpha narrow filter measurements (2)
103 I1 --- o_alphaw Number of Halpha wide filter measurements (2)
105-109 F5.3 mag alpha ? α index (2)
111-114 F4.3 mag e_alpha ? Error of α index
117-119 A3 --- Pum Star number from Pummerer (1915, Publ. Sternw.
Wien Ottakring 6 part VII,
CL* NGC 663 PUM II-NNN)
121-124 A4 --- Gus ? Star number from Gushee (1919AJ.....32..117G 1919AJ.....32..117G,
CL* NGC 663 G NNN)
125 A1 --- u_Gus [:] Uncertainty flag on Gus number
126-129 A4 --- Wal ? Star number from Wallenquist
(1929MeUpp..42.....W 1929MeUpp..42.....W, NGC 663 NNN)
130 A1 --- u_Wal [:] Uncertainty flag on Wal number
131 A1 --- n_Wal [*] *: object in table3.dat
133-134 I2 --- Zug ? Star number from Zug (1933LicOB..16..119Z 1933LicOB..16..119Z,
Cl* NGC 663 ZUG NN)
136-138 A3 --- BG Star number from Becker & Guenther
(1947AN....275..145B 1947AN....275..145B, Cl* NGC 663 BG NNN)
140-142 I3 --- HH ? Star number from Hopmann & Haidrich
(1959MiWie..10..129H 1959MiWie..10..129H, Cl* NGC 663 HH NNN)
144-145 I2 --- HE ? Star number from Hoag et al.
(1961PUSNO..17..343H 1961PUSNO..17..343H, Cl* NGC 663 HOAG NNW),
photoelectric sequence
147-149 I3 --- HP ? Star number from Hoag et al.
(1961PUSNO..17..343H 1961PUSNO..17..343H, Cl* NGC 663 HOAG 1NN),
photographic sequence
150 A1 --- u_HP [:] Uncertainty flag on HP number
151-153 I3 --- MH ? Star number from McCuskey & Houk
(1964AJ.....69..412M 1964AJ.....69..412M, Cl* NGC 663 MH NNN)
154 A1 --- u_MH [:] Uncertainty flag on MH number
155-157 I3 --- Lat ? Star number from Latypov
(1973TITas..39...12L 1973TITas..39...12L, Cl* NGC 663 L NNNN)
159-163 I5 --- MV ? Star number from Moffat & Vogt
(1974VeBoc...2....1M 1974VeBoc...2....1M, Cl* NGC 663 MV NNNNN)
165-167 I3 --- BR ? Star number from van den Bergh & de Roux
(1978AJ.....83.1075V 1978AJ.....83.1075V, Cl* NGC 663 VD 3-NNN)
169-171 A3 --- Tap Star number from Tapia et al.
(1991MNRAS.253..649T 1991MNRAS.253..649T, Cl* NGC 663 HOAG NNW)
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Note (1): Stars are listed according to the increasing right ascension.
In Simbad, objects are identified as [PKK2001] JHHMMSS.ss+DDMMSS.s
Note (2): The Hα photometry we made was used to find stars showing
Hα emission. This was done by means of an α index, defined
as a difference between the magnitudes of a star through a narrow and
a wide filter. Our filters and, consequently, the α index
resembles those used by others, namely:
Abt & Golson (1966, Cat. J/ApJ/143/306),
Tebbe (1969, Cat. J/AJ/74/920),
Feinstein (1974, Cat. J/MNRAS/169/171),
Dachs & Schmidt-Kaler (1975, Cat. J/A+AS/21/81),
Claria & Escosteguy (1981PASP...93..636C 1981PASP...93..636C),
Strauss & Ducati (1981A&AS...44..337S 1981A&AS...44..337S), and
Goderya & Schmidt (1994ApJ...426..159G 1994ApJ...426..159G).
We made, however, no attempt to transform our α to that defined
by others; it was left in the instrumental system.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- San ? Star number according to Sanduleak
(1979AJ.....84.1319S 1979AJ.....84.1319S, 1990AJ....100.1239S 1990AJ....100.1239S,
Cl* NGC 663 SAN NNN in Simbad)
4- 7 A4 --- Wal Star number according to Wallenquist
(1929MeUpp..42.....W 1929MeUpp..42.....W)
9- 19 F11.3 d Epoch HJD of the epoch of observation
21- 25 F5.3 mag alpha α index
27- 31 F5.3 mag e_alpha Error of α index
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Acknowledgements: Andrzej Pigulski
(End) Patricia Bauer [CDS] 11-Oct-2001