J/A+A/513/A29 RACE-OC project: M11 (NGC6705) (Messina+, 2010)
RACE-OC Project: Rotation and variability in the open cluster M11 (NGC6705).
Messina S., Padmakar Parihar, Koo J.R., Kim S.-L., Rey S.-C., Lee C.-U.
<Astron. Astrophys. 513, A29 (2010)>
=2010A&A...513A..29M 2010A&A...513A..29M
ADC_Keywords: Clusters, open ; Stars, late-type ; Photometry, UBV
Keywords: stars: activity - stars: late-type - stars: rotation - starspots -
open clusters and associations: general -
open clusters and associations: individual: M11
Abstract:
Rotation and magnetic activity are intimately linked in main-sequence
stars of G or later spectral types. The presence and level of magnetic
activity depend on stellar rotation, and rotation itself is strongly
influenced by strength and topology of the magnetic fields. Open
clusters represent especially useful targets to investigate the
rotation/activity/age connection. The open cluster M11 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 with different ages.
Photometric observations of the open cluster M11 were carried out in
June 2004 using LOAO 1m telescope. The rotation periods of the cluster
members are determined by Fourier analysis of photometric data time
series. We further investigated the relations between the surface
activity, characterized by the light curve amplitude, and rotation. We
have discovered a total of 75 periodic variables in the M11 FoV, of
which 38 are candidate cluster members. Specifically, among cluster
members we discovered 6 early-type, 2 eclipsing binaries and 30
bona-fide single periodic late-type variables. Considering the
rotation periods of 16 G-type members of the almost coeval 200-Myr M34
cluster, we could determine the rotation period distribution from a
more numerous sample of 46 single G stars at an age of about 200-230
Myr and determine a median rotation period P=4.8d. A comparison with
the younger M35 cluster (∼150Myr) and with the older M37 cluster
(∼550Myr) shows that G stars rotate slower than younger M35 stars and
faster than older M37 stars. The measured variation of the median
rotation period is consistent with the scenario of rotational braking
of main-sequence spotted stars as they age.
Description:
In Table 1, we summarise the results of our period search analysis. In
Table 2 we give the time series averaged V-band magnitudes (non
corrected for interstellar reddening) for the periodic variables
newly discovered in the FoV of M11.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 75 Summary of rotation period search
table2.dat 33 8141 Photometric time series of periodic variables
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See also:
J/A+AS/128/255 : Proper motions in M 11 (Su+ 1998)
J/A+A/412/721 : CCD Δa-photometry of 5 open clusters (Paunzen+, 2003)
J/PASP/119/1233 : BV photometry of M11 stars (Koo+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Target Target's internal ID number
7- 11 I5 --- Webda ?=- Target's Webda number (G1)
13- 14 I2 h RAh Right ascension (J2000.0)
16- 17 I2 min RAm Right ascension (J2000.0)
19- 24 F6.3 s RAs Right ascension (J2000.0)
26 A1 --- DE- Declination sign (J2000.0)
27- 28 I2 deg DEd Declination (J2000.0)
30- 31 I2 arcmin DEm Declination (J2000.0)
33- 37 F5.2 arcsec DEs Declination (J2000.0)
39- 45 F7.4 d Per Period from Scargle analysis (2)
46- 52 F7.4 d e_Per Uncertainty on the adopted period
54- 58 F5.2 --- PN Normalized power from Scargle periodogram (2)
60- 64 F5.2 mag <Vmag> Mean V magnitude
66- 70 F5.2 mag (B-V)0 Dereddened B-V color index
72- 77 F6.4 mag Vsig V-band photometric accuracy
79- 84 F6.4 mag Vamp V-band light curve amplitude
86 A1 --- Mm [abn] Membership code (1)
88 A1 --- Ecl [yn] detected eclipse (yes or no)
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Note (1): Membership probability flag as follows:
n = non members
b = low-probability members
a = high-probability members
Note (2): The Scargle technique has been developed to search for
significant periodicities in unevenly sampled data, see Scargle
1982ApJ...263..835S 1982ApJ...263..835S), Horne & Baliunas (1986ApJ...302..757H 1986ApJ...302..757H). The
algorithm calculates the normalized power of each frequency PN. The
normalized power corresponding to a probability of a false alarm of 1%
(i.e. the detected frequency is due to the noise at a probability
level of 1%) is PN=9.2.
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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- 5 I5 --- Target Target's internal ID number (G1)
7- 18 F12.4 d HJD Heliocentric Julian Day
20- 26 F7.4 mag Vmag V-band magnitude
28- 33 F6.4 mag e_Vmag Uncertainty on Vmag
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Global notes:
Note (G1): Wedba numbers:
* 1-9804, NGC 6705 NNNN in Simbad
* 10095-26763, from Koo et al., 1997, Cat. J/PASP/119/1233
Acknowledgements:
S. Messina, sme(at)oact.inaf.it
(End) Patricia Vannier [CDS] 29-Dec-2009