J/ApJ/733/115 Rotation periods and membership in M34 (Meibom+, 2011)
The color-period diagram and stellar rotational Evolution - New rotation period
measurements in the open cluster M34.
Meibom S., Mathieu R.D., Stassun K.G., Liebesny P., Saar S.H.
<Astrophys. J., 733, 115 (2011)>
=2011ApJ...733..115M 2011ApJ...733..115M
ADC_Keywords: Clusters, open ; Stars, late-type ; Radial velocities ; Photometry
Keywords: open clusters and associations: individual (M34) - stars: activity -
stars: late-type - stars: rotation - starspots
Abstract:
We present the results of a 5 month photometric time-series survey for
stellar rotation periods combined with a 4 year radial-velocity survey
for membership and binarity in the 220Myr open cluster M34. We report
surface rotation periods for 120 stars, 83 of which are kinematic and
photometric late-type cluster members. A comparison to previous work
serves to illustrate the importance of high-cadence long baseline
photometric observations and membership information. The new M34
periods are less biased against slow rotation and cleaned for
non-members. The rotation periods of the cluster members span over
more than an order of magnitude from 0.5 days up to 11.5 days, and
trace two distinct rotational sequences -fast (C) and moderate-to-slow
(I)- in the color-period diagram. The sequences represent two
different states (fast and slow) in the rotational evolution of the
late-type cluster members. We use the color-period diagrams for M34
and for younger and older clusters to estimate the timescale for the
transition from the C to the I sequence and find ≲150Myr,
∼150-300Myr, and ∼300-600 Myr for G, early-mid K, and late K dwarfs,
respectively. The small number of stars in the gap between C and I
suggests a quick transition. We determine a gyrochronology age of
240Myr for M34.
Description:
We obtained time-series photometry over a time span of 143 days for a
40'x40' region centered on the open cluster M34. The photometric data
were obtained in the Johnson V band with the WIYN 0.9m telescope on
Kitt Peak. The data set presented is composed of images from
high-frequency (approximately once per hour for 5-6hr per night)
time-series photometric observations over 16 full nights from 2002
December 2-17, complemented with a queue-scheduled observing program
over 143 nights from 2002 October 22 to 2003 March 11. We obtain a
photometric precision of ∼0.5% and light curves for 5656 stars with
12≲V≲20.8.
We observed M34 from 2001 to 2004 as part of the WIYN Open Cluster
Study (Mathieu 2000ASPC..198..517M 2000ASPC..198..517M). A total of 3320 spectra has been
obtained of 437 FGK stars within a 1° field centered on the
cluster. Radial velocities with a precision of ≲0.5km/s (Geller et
al. 2008, Cat. J/AJ/135/2264) were derived from the spectra via
cross-correlation with a high signal-to-noise sky spectrum. Of the 120
stars with rotation periods presented in this study, 74 have one or
more radial-velocity measurements (the remainder being below the faint
limit of the spectroscopic survey or photometric non-members).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 120 Data for the 120 stars with measured rotation
periods in the field of M34
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See also:
J/ApJ/695/679 : Stellar rotation in M35 (Meibom+, 2009)
J/AJ/135/2264 : Stellar radial velocities in NGC 188 (Geller+, 2008)
J/MNRAS/370/954 : VRIHalpha photometry of M34 (Irwin+, 2006)
J/ApJ/602/L117 : Oxygen in Pleiades and M34 dwarfs (Schuler+, 2004)
J/AJ/111/1193 : Proper motion in M34 (Jones+ 1996)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/120] Running index number (1)
5 I1 h RAh Hour of Right Ascension (J2000)
7- 8 I2 min RAm Minute of Right Ascension (J2000)
10- 15 F6.3 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- Sign of Declination (J2000)
18- 19 I2 deg DEd Degree of Declination (J2000)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000)
24- 29 F6.3 arcsec DEs Arcsecond of Declination (J2000)
31- 35 F5.2 d Prot Rotation period
37- 41 F5.2 mag V0mag Extinction-corrected V band magnitude
43- 46 F4.2 mag (B-V)0 ? Reddening corrected (B-V) color index
48- 49 I2 --- o_RVel ? Number of RV measurements
51- 55 F5.1 km/s RVel ? Mean radial velocity
57- 60 F4.1 km/s e_RVel ? Uncertainty in RVel
62- 63 I2 % PRV ? Membership probability from radial
velocity (2)
65- 66 I2 % PPM ? Membership probability from proper-motion;
Jones & Prosser 1996, Cat. J/AJ/111/1193;
<Cl* NGC 1039 JP NNN> in Simbad
68- 69 A2 --- Mm [PKNM] Membership code (3)
71 A1 --- Rot [icg-] Sequence code (4)
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Note (1): Assigned to 120 rotators after sorting by rotation period.
Note (2): Using the formalism by Vasilevskis et al. (1958AJ.....63..387V 1958AJ.....63..387V).
Note (3): Membership as follows:
PM = Photometric Member (described in Section 2.3);
KM = Kinematic (and Photometric) Member;
NM = Non-Member.
We have adopted PRV=40% as the threshold for assigning
radial-velocity cluster membership.
Note (4): Sequence code as follows:
i = I sequence (moderate-to-slow rotational sequence in the color-period
diagram);
c = C sequence (fast rotational sequence in the color-period diagram);
g = gap.
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History:
From electronic version of the journal
References:
Meibom et al. Paper I: M35. 2009ApJ...695..679M 2009ApJ...695..679M Cat. J/ApJ/695/679
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Nov-2012