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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
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). 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 71 120 Data for the 120 stars with measured rotation periods in the field of M34
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
Bytes Format Units Label Explanations
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)
Note (1): Assigned to 120 rotators after sorting by rotation period. Note (2): Using the formalism by Vasilevskis et al. (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.
History: From electronic version of the journal References: Meibom et al. Paper I: M35. 2009ApJ...695..679M Cat. J/ApJ/695/679
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Nov-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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