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 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 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:
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FileName Lrecl Records Explanations
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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
(table F1 in the paper)
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See also:
J/MNRAS/430/1433 : NGC 2264 members periods with CoRoT (Affer+, 2013)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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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)
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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 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).
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Acknowledgements:
Laura Venuti, lvenuti(at)astropa.unipa.it
(End) Laura Venuti [INAF-OAPa, Italy], Patricia Vannier [CDS] 31-Oct-2016