J/A+A/483/253 BV photometry of NGC 2099 variables (Messina+, 2008)
RACE-OC Project: Rotation and variability in the open cluster NGC 2099 (M37).
Messina S., Distefano D., Padmakar P., Kang Y.B., Kim S.-L., Rey S.-C.,
Lee C.-U
<Astron. Astrophys. 483, 253 (2008)>
=2008A&A...483..253M 2008A&A...483..253M
ADC_Keywords: Clusters, open ; Binaries, eclipsing ; Photometry, UBV
Keywords: stars: activity - stars: binaries: close - stars: late-type -
stars: rotation - stars: starspots -
Galaxy: open clusters and associations: individual: NGC 2099
Abstract:
Rotation and solar-type magnetic activity are closely related to each
other in main-sequence stars of G or later spectral types. The
presence and level of magnetic activity depend on star's rotation, and
rotation itself is strongly influenced by strength and topology of the
magnetic fields. Open clusters represent especially useful targets to
investigate the connection between rotation and activity. The open
cluster NGC 2099 has been studied as a part of the RACE-OC project
(Rotation and ACtivity Evolution in Open Clusters), which is aimed at
exploring the evolution of rotation and magnetic activity in the
late-type members of open clusters of different ages. We collected
time series CCD photometric observations of this cluster in January
2004, and we determined the presence of periodicities in the flux
variation related to the stellar rotation by Fourier analysis. We
investigate the relations between activity manifestations, such as the
light curve amplitude, and global stellar parameters. We have
discovered 135 periodic variables, 122 of which are candidate cluster
members. Determination of rotation periods of G- and K-type stars has
allowed us to better explore the evolution of angular momentum at an
age of about 500Myr. In our analysis, we have also identified 3 new
detached eclipsing binary candidates among cluster members. A
comparison with the older Hyades cluster (∼625Myr) shows that the
newly-determined distribution of rotation periods is consistent with
the scenario of rotational braking of main-sequence spotted stars as
they age. However, a comparison with the younger M34 cluster (∼200Myr)
shows that the G8-K5 members of these clusters have the same rotation
period distribution.
That is, G8-K5 members in NGC 2099 seem to have experienced no
significant braking in the age range from ∼200 to ∼500Myr. Finally,
NGC 2099 members have a smaller level of photospheric magnetic
activity, as measured by light curve amplitude, than in younger stars
of the same mass and rotation, suggesting that the activity level also
depends on some other age-dependent parameters.
Description:
We list the coordinates, and dereddened V magnitude and B-V color of
periodic variables in Table 1 whereas in Table 2 we give the summary
of the period search analysis. In Table 3 we give the time series
V-band magnitudes (non corrected for interstellar reddening) for the
periodic candidate cluster members.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 46 153 Summary of photometric observations
table2.dat 102 120 Summary of correlation and regression analyses
table3.dat 36 19120 Photometric data of periodic candidate cluster
members
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See also:
J/A+A/480/495 : Patterns of color variations in close binaries (Messina, 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Target Target's Identification Number
6- 7 I2 h RAh Right ascension (J2000.0)
9- 10 I2 min RAm Right ascension (J2000.0)
12- 17 F6.3 s RAs Right ascension (J2000.0)
19 A1 --- DE- Declination sign (J2000.0)
20- 21 I2 deg DEd Declination (J2000.0)
23- 24 I2 arcmin DEm Declination (J2000.0)
26- 30 F5.2 arcsec DEs Declination (J2000.0)
32- 37 F6.3 mag (Vmag)0 Dereddened V magnitude
39- 44 F6.3 mag (B-V)0 Dereddened (B-V) colour index
46 A1 --- n_Target [*] indicates light curve in table3
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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- 4 I4 --- Target Target's Identification Number
6- 11 F6.3 d PScargle Period from Scargle analysis
13- 18 F6.3 d Pclean Period from CLEAN analysis
20- 25 F6.2 --- Pnorm Normalized power from Scargle periodogram
27- 32 F6.3 d Per Adopted period
34- 38 F5.3 d e_Per Uncertainty on the adopted period
40- 44 F5.2 mag Vmean Mean V magnitude
46- 51 F6.4 mag e_Vmean V-magnitude standard deviation
53- 58 F6.4 mag Vacc V-band photometric accuracy
60- 65 F6.4 mag Vamp V-band light curve amplitude
67- 69 I3 --- o_Vmean Number of observations
71- 81 A11 --- Note Note on membership and variable type (1)
83-102 A20 --- Kang Name in Kang et al. (2007PASP..119..239K 2007PASP..119..239K) for
already known variables
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Note (1): Note as follows:
cm = candidate cluster member
EW = W UMa-type binary
EA = Algol type
RRc = RR Lyrae RRc type
delta Scuti = delta Scuti type
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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- 4 I4 --- Target Target's Identification Number
7- 18 F12.4 d HJD Helicentric Julian Day
21- 27 F7.4 mag Vmag V-band magnitude
31- 36 F6.4 mag e_Vmag Uncertainty on Vmag
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Acknowledgements:
Sergio Messina, sergio.messina(at)oact.inaf.it
(End) Patricia Vannier [CDS] 17-Mar-2008