J/A+A/471/515 V light curves of NGC 6791 variable stars (De Marchi+, 2007)
Variable stars in the open cluster NGC 6791 and its surrounding field.
De Marchi F., Poretti E., Montalto M., Piotto G., Desidera S., Bedin L.R.,
Claudi R., Arellano Ferro A., Bruntt H., Stetson P.B.
<Astron. Astrophys. 471, 515 (2007)>
=2007A&A...471..515D 2007A&A...471..515D
ADC_Keywords: Clusters, open ; Stars, variable ; Photometry
Keywords: stars: starspots - stars: statistics - stars: variables: general -
stars: binaries: eclipsing - stars: novae, cataclysmic variables -
open clusters and associations: individual: NGC 6791
Abstract:
This work presents a high-precision variability survey in the field of
the old, super metal-rich open cluster NGC 6791.
The data sample consists of more than 75,000 high-precision CCD time
series measurements in the V band obtained mainly at the
Canada-France-Hawaii Telescope, with additional data from S. Pedro
Martir and Loiano observatories, over a time span of ten nights. The
field covers an area of 42x28arcmin2.
We have discovered 260 new variables and re-determined periods and
amplitudes of 70 known variable stars. By means of a photometric
evaluation of the membership in NGC 6791, and a preliminary membership
based on the proper motions, we give a full description of the
variable content of the cluster and surrounding field in the range
16<V<23.5. Accurate periods can be given for the variables with
P<4.0d, while for ones with longer periods the limited time-baseline
hampered precise determinations. We categorized the entire sample as
follows: 6 pulsating, 3 irregular, 3 cataclysmic, 89 rotational
variables and 61 eclipsing systems; moreover, we detected 168
candidate variables for which we cannot give a variability class since
their periods are much longer than our time baseline.
On the basis of photometric considerations, and of the positions of
the stars with respect to the center of the cluster, we inferred that
11 new variable stars are likely members of the cluster, for 22 stars
the membership is doubtful and 137 are likely non-members. We also
detected an outburst of about 3 mag in the light curve of a very faint
blue star belonging to the cluster and we suggest that this star could
be a new U Gem (dwarf nova) cataclysmic variable.
Description:
341 Light curves of variable stars located in an area of 42x28arcmin2
centered on the open cluster NGC 6791. Data was taken at
Canada-France-Hawaii, Loiano and San Pedro Martir telescopes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 115 341 List of variable stars
lc/* . 341 Individual light curves
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See also:
J/A+AS/114/1 : CCD UBVI photometry of NGC 6791 (Kaluzny+, 1995)
J/PASP/115/413 : BVI photometry in the open cluster NGC 6791 (Stetson+, 2003)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Variable name
13- 17 A5 --- VType Variable classification (1)
20- 29 F10.6 deg RAdeg Right ascension in decimal degrees (J2000.0)
31- 39 F9.6 deg DEdeg Declination in decimal degrees (J2000.0)
42- 47 F6.3 mag Umag ?=99.999 U mean magnitude
49- 54 F6.3 mag Bmag ?=99.999 B mean magnitude
56- 61 F6.3 mag Vmag ?=99.999 V mean magnitude
63- 68 F6.3 mag Imag ?=99.999 I mean magnitude
70 A1 --- Phot [ks*] Data source (2)
75- 85 F11.3 d Epoch ?=9999999.999 HJD Instant of minimum (maximum)
of brightness (3)
87- 94 F8.5 d Period ?=99.99999 Period of variability
97-101 F5.3 mag Ampl Amplitude
105-109 A5 --- Memb Membership (4)
112-115 F4.1 arcmin Dist Distance from the center of the cluster
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Note (1): RO1, RO2 and LON mean: rotational variables with single-wave
light curves, rotational variables with double-wave light curves,
variables with periods much longer than our time baseline,
respectively. The stars labeled with 'CST' are previously discovered
variables for which we found no variability (e.g.: eclipsing variables
with period longer than our time baseline and without eclipses during
our survey).
Note (2): Data source as follows:
k = Kaluzny et al. (1995, Cat. J/A+AS/114/1)
s = Stetson et al. (2003, Cat. J/PASP/115/413)
* = no data
Note (3): Epoch is the instant (HJD) of maximum brightness for pulsating
and rotational variables, the instant of the primary minimum for
eclipsing variables.
Note (4): If a number, correspond to preliminary membership probability
based on the proper motions (Cudworth, private communication).
Else:
m = likely member
m? = uncertain membership
nm = likely non-member
nd1 = no photometric data are available to advance hypothesis about
the membership, but the star is located nearer than 10arcmin
from the center of the cluster (fiducial limit of the cluster,
see text for details).
nd2 = no photometric data are available and the star is located
further than 10 arcmin from the center (in this case we
strongly suggest that the star does not belongs to the cluster).
mB06 = member (from Bedin et al., 2006A&A...460L..27B 2006A&A...460L..27B)
nmB06 = non-member (from Bedin et al., 2006A&A...460L..27B 2006A&A...460L..27B)
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Byte-by-byte Description of file: lc/*
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Bytes Format Units Label Explanations
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2- 16 F15.7 d HJD Time (HJD)
22- 27 F6.3 mag Vmag Apparent magnitude (V band)
34- 38 F5.3 mag e_Vmag Error in Vmag
42 A1 --- Tel [cls] Telescope code (1)
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Note (1): Telescope from which the data was taken as follows:
c = CFH Telescope
l = Loiano
s = San Pedro Martir
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Acknowledgements:
We are grateful to Kyle Cudworth kindly providing us with preliminary
cluster membership probabilities.
Fabrizio De Marchi, fabrizio.demarchi(at)unipd.it
(End) Patricia Vannier [CDS] 07-Aug-2007