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J/A+A/599/A23      Accretion-rotation connection in NGC 2264     (Venuti+, 2017)

CSI 2264: Investigating rotation and its connection with disk accretion in the young open cluster NGC 2264. Venuti L., Bouvier J., Cody A.M., Stauffer J.R., Micela G., Rebull L.M., Alencar S.H.P., Sousa A.P., Hillenbrand L.A., Flaccomio E. <Astron. Astrophys. 599, A23 (2017)> =2017A&A...599A..23V (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; YSOs ; Photometry Keywords: accretion, accretion disks - stars: low-mass - stars: pre-main sequence - stars: rotation - stars: variables: T Tauri, Herbig Ae/Be - open clusters and associations: individual: NGC 2264 Abstract: The low spin rates measured for solar-type stars at an age of a few Myr (∼10% of the break-up velocity) indicate that some mechanism of angular momentum regulation must be at play in the early pre-main sequence. This may be associated with magnetospheric accretion and star-disk interaction, as suggested by observations that disk-bearing objects (CTTS) are slower rotators than diskless sources (WTTS) in young star clusters. We characterize the rotation properties for members of the star-forming region NGC 2264 (∼3Myr) as a function of mass, and investigate the accretion-rotation connection at an age where about 50% of the stars have already lost their disks. We examined a sample of 500 cluster members (40% with disks, 60% without disks), distributed in mass between ∼0.15 and 2M, whose photometric variations were monitored in the optical for 38 consecutive days with the CoRoT space observatory. Light curves were analyzed for periodicity using three different techniques: the Lomb-Scargle periodogram, the autocorrelation function and the string-length method. Periods were searched in the range between 0.17-days (i.e., 4h, twice the data sampling adopted) and 19-days (half the total time span). Period detections were confirmed using a variety of statistical tools (false alarm probability, Q-statistics), as well as visual inspection of the direct and phase-folded light curves. Description: Our study aims at characterizing the rotation properties for members of the star-forming region NGC 2264 (3Myr), and at investigating the accretion-rotation connection at an age where about 50% of the stars have already lost their disks. We monitored the photometric variations in the optical for about 500 cluster members for 38 consecutive days, using the CoRoT space observatory. Light curves were analyzed for periodicity using three different techniques: the Lomb-Scargle periodogram, the autocorrelation function and the string-length method. In table4, we present the results of our period analysis. For each object in the sample, identified by a name (following the project convention) and the spatial coordinates, we report the object class (CTTS/WTTS), the light curve identifier in the CoRoT database, the light curve morphology type, the mass, the period extracted from the dataset analyzed here, the false alarm probability associated with the period detection, the Q-statistics for period reliability (Cody et al. 2014AJ....147...82C), and previous period detections for the same objects (where applicable) from the results of an earlier CoRoT run on the cluster (Affer et al., 2013, Cat. J/MNRAS/430/1433). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 82 532 Identifier, coordinates, classification, light curve type, mass, period detections for NGC 2264 members probed in this study
See also: J/MNRAS/430/1433 : NGC 2264 members periods with CoRoT (Affer+, 2013) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Name Object identifier 8- 16 F9.5 deg RAdeg Right ascension (J2000) (1) 18- 25 F8.5 deg DEdeg Declination (J2000) (1) 27 A1 --- Class Object classification (2) 29- 37 I9 --- CoRoT CoRoT light curve number 39- 45 A7 --- LC ?=- Light-curve morphology class (3) 47- 50 F4.2 Msun Mass ?=- Mass of the object 52- 57 F6.3 d P2011 ?=- Rotation period derived from this study 59 A1 --- l_FAP Limit flag on FAP 60- 65 E6.3 --- FAP ?=- False-Alarm Probability (4) 68 A1 -- l_Q [~<] Limit flag on Q 69- 73 F5.2 --- Q ?=- Q-statistics for the extracted period (5) 75- 80 F6.3 d P2008 ?=- Rotation period retrieved from Affer et al. (2013, Cat. J/MNRAS/430/1433) 82 A1 --- n_P2008 [N-] Note on P2008 (6)
Note (1): Coordinates from the 2MASS survey. Note (2): Object classification as follows: c = CTTS w = WTTS - = non-classified Note (3): Light-curve morphology class as follows: B = burster U = unclassifiable variable type S = stochastic N = non-variable D = dipper QPS = quasi-periodic symmetric QPD = quasi-periodic dipper P = periodic MP = multi-periodic EB = eclipsing binary L = long-timescale variable Be = beats Note (4): Fraction of times a periodogram power higher than that corresponding to the extracted period occurs, at the same frequency, among 10,000 "noise-like" light curves built by dividing the original light curve in 12 h-long segments and reassembling them in random order. Note (5): Ratio of the amounts of effective light curve rms (rms2-sigma2) measured after and before subtracting the periodic trend from the light curve (see definition in Cody et al., 2014AJ....147...82C). A "--" indicates that the computed value of Q, associated with the period listed, is not reported because affected by systematics or by an erroneous estimate of the photometric uncertainty on the light curve. Q is not reported for multi-periodic (MP) objects. Note (6): Note on P2008 as follows: N = aperiodic; - = object not present in Affer et al.'s (2013, Cat. J/MNRAS/430/1433) sample N.B.: multiple periods are not investigated in the study of Affer et al. (2013, Cat. J/MNRAS/430/1433).
Acknowledgements: Laura Venuti, lvenuti(at)astropa.unipa.it
(End) Laura Venuti [INAF-OAPa, Italy], Patricia Vannier [CDS] 31-Oct-2016
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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