J/MNRAS/370/954 VRIHalpha photometry of M34 (Irwin+, 2006)
The Monitor project: rotation of low-mass stars in the open cluster M34.
Irwin J., Aigrain S., Hodgkin S., Irwin M., Bouvier J., Clarke C., Hebb L.,
Moraux E.
<Mon. Not. R. Astron. Soc., 370, 954-974 (2006)>
=2006MNRAS.370..954I 2006MNRAS.370..954I
ADC_Keywords: Clusters, open ; Photometry, VRI ; Photometry, H-alpha
Keywords: techniques: photometric - surveys - stars: rotation -
open clusters and associations: individual: M34
Abstract:
We report on the results of a V- and i-band time-series photometric
survey of M34 (NGC 1039) using the Wide Field Camera (WFC) on the
Isaac Newton Telescope (INT), achieving better than 1 per cent
precision per data point for 13~<i~<17. Candidate cluster members were
selected from a V versus VI colour-magnitude diagram over 14<V<24
(0.12<M/M☉<1.0), finding 714 candidates, of which we expect ∼400
to be real cluster members (taking into account contamination from the
field). The mass function was computed, and found to be consistent
with a lognormal distribution in dN/dlogM. Searching for periodic
variable objects in the candidate members gave 105 detections over the
mass range 0.25<M/M☉<1.0. The distribution of rotation periods
for 0.4<M/M☉<1.0 was found to peak at ∼7d, with a tail of fast
rotators down to periods of ∼0.8d. For 0.25<M/M☉<0.4 we found a
peak at short periods, with a lack of slow rotators (e.g. P>5d),
consistent with the work of other authors at very low masses. Our
results are interpreted in the context of previous work, finding that
we reproduce the same general features in the rotational period
distributions. A number of rapid rotators were found with velocities
∼ a factor of 2 lower than in the Pleiades, consistent with models of
angular momentum evolution assuming solid body rotation without
needing to invoke core-envelope decoupling.
Description:
Photometric monitoring data were obtained using the 2.5m INT, with the
Wide Field Camera (WFC) during a 10-night observing run in 2004
November. This instrument provides a field of view (FOV) of
approximately 34x34arcmin2 at the prime focus of the INT, over a
mosaic of four 2x4k pixel CCDs, with ∼0.33arcsec/pixels. Our primary
target was the ONC, which was observable for only half the night from
La Palma, so the first ∼4.5h of each night were used to observe M34.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 98 105 Summary of the properties of our 105
M34 rotation candidates
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See also:
J/AJ/111/1193 : Proper motion in M34 (Jones+ 1996)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [M34-]
5- 10 A6 --- M34 Identifier (N-NNNN),
Cl* NGC 1039 IAH N-NNN in Simbad
13- 14 I2 h RAh Right ascension (J2000)
16- 17 I2 min RAm Right ascension (J2000)
19- 23 F5.2 s RAs Right ascension (J2000)
25 A1 --- DE- Declination sign (J2000)
26- 27 I2 deg DEd Declination (J2000)
29- 30 I2 arcmin DEm Declination (J2000)
32- 35 F4.1 arcsec DEs Declination (J2000)
37- 41 F5.2 mag Vmag Johnson V magnitude
43- 47 F5.2 mag Rcmag ? Cousins R magnitude
49- 53 F5.2 mag Icmag Cousins I magnitude
55- 59 F5.2 mag Hamag Hα magnitude (approximately equivalent to
r-band magnitudes for a continuum source)
61- 66 F6.3 d Per Period
67 A1 --- n_Per [abc] Note on Per (1)
69- 73 F5.3 mag AV Amplitude in V band
75- 79 F5.3 mag AI Amplitude in I band
81- 84 F4.2 solMass Mass Interpolated mass (derived using I magnitude)
86- 89 F4.2 solRad Rad Interpolated radius (derived using I magnitude)
91- 93 I3 --- JP ? Jones & Prosser (1996, Cat. J/AJ/111/1193)
number, Cl* NGC 1039 JP NNN in Simbad
95- 98 F4.1 km/s vsini ? Rotational velocity
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Note (1): Notes as follows:
a = cases where the period was ambiguous (with both long and short
periods fitting equally well to the observations)
b = poorly constrained long period (due to the short observing window)
c = objects where the V-band detection was saturated, so the i band
only was used to fit the period (NB: the V-band magnitudes and
amplitudes are unreliable for these objects)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 19-Feb-2007