J/A+A/644/A16 NGC 6774 cool stars rotation periods (Gruner+, 2020)
Rotation periods for cool stars in the open cluster Ruprecht 147 (NGC 6774).
Implications for gyrochronology.
Gruner D., Barnes S.A.
<Astron. Astrophys. 644, A16 (2020)>
=2020A&A...644A..16G 2020A&A...644A..16G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, variable ; Stars, late-type ; Photometry
Keywords: stars: late-type - stars: low-mass - stars: rotation -
stars: solar-type
Abstract:
Gyrochronology allows the derivation of ages for cool main sequence
stars based on their observed rotation periods and masses, or a
suitable proxy thereof. It is increasingly well-explored for FGK
stars, but requires further measurements for older ages and K-M-type
stars.
We study the 2.7Gyr-old open cluster Ruprecht 147 to compare it with
the previously-studied, but far more distant, NGC 6819 cluster, and
especially to measure cooler stars than was previously possible there.
We constructed an inclusive list of 102 cluster members from prior
work, including Gaia DR2, and for which light curves were also
obtained during Campaign 7 of the Kepler/K2 space mission. We placed
them in the cluster color-magnitude diagram and checked the related
information against appropriate isochrones. The light curves were then
corrected for data systematics using Principal Component Analysis on
all observed K2 C07 stars and subsequently subjected to periodicity
analysis.
Periodic signals are found for 32 stars, 21 of which are considered to
be both highly reliable and to represent single, or effectively
single, Ru 147 stars. These stars cover the spectral types from late-F
to mid-M stars, and they have periods ranging from 6d-33d,
allowing for a comparison of Ruprecht 147 to both other open clusters
and to models of rotational spindown. The derived rotation periods
connect reasonably to, overlap with, and extend to lower masses the
known rotation period distribution of the 2.5 Gyr-old cluster NGC
6819.
The data confirm that cool stars lie on a single surface in rotation
period-mass-age space, and they simultaneously challenge its commonly
assumed shape. The shape at the low mass region of the color-period
diagram at the age of Ru 147 favors a recently-proposed model which
requires a third mass-dependent timescale in addition to the two
timescales required by a former model, suggesting that a third
physical process is required to model rotating stars effectively.
Description:
We present rotation periods for late-type stars in the open cluster
Ruprecht 147. Those are derived from EVEREST light curves based on
Kepler/K2 observations.
The table contains commonly used identifiers and magnitudes for each
star for which a period is found. For each star, we provide the
modified EVEREST light curve, the trend correction based on the PCA
and the detrended light curve used for the period analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
periods.dat 237 32 Sample stars: identifiers, colors and periods
fits/* . 32 Individual fits files
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: periods.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- EPIC EPIC catalog ID (Cat. IV/34)
11- 29 I19 --- GaiaDR2 Gaia DR2 identifier (Cat. I/345)
31- 47 A17 --- 2MASS 2MASS identifier (Cat. II/246)
49- 58 F10.6 deg RAdeg Right ascension (J2000)
60- 69 F10.6 deg DEdeg Declination (J2000)
71- 75 F5.3 mag (BP-RP)0 Dereddened Gaia Bp-Rp color index
77- 81 F5.3 mag (B-V)0 ? Dereddend B-V color index
83- 87 F5.3 mag (B-V)calc Calculated B-V color index
89- 94 F6.3 mag Gmag Gaia G band magnitude
96-100 F5.3 mag e_Gmag Error on Gmag
102-107 F6.3 mag BPmag Gaia Bp band magnitude
109-113 F5.3 mag e_BPmag Error on BPmag
115-120 F6.3 mag RPmag Gaia Rp band magnitude
122-126 F5.3 mag e_RPmag Error on RPmag
128-133 F6.3 mag Bmag ? Johnson B band magnitude
135-139 F5.3 mag e_Bmag ? Error on Bmag
141-146 F6.3 mag Vmag ? Johnson V band magnitude
148-152 F5.3 mag e_Vmag ? Error on Vmag
154-159 F6.3 mag Jmag 2MASS J band magnitude
161-165 F5.3 mag e_Jmag Error on Jmag
167-172 F6.3 mag Hmag 2MASS H band magnitude
174-178 F5.3 mag e_Hmag Error on Hmag
180-185 F6.3 mag Kmag 2MASS K band magnitude
187-191 F5.3 mag e_Kmag Error on Kmag
193-198 F6.3 d Per Stellar period
200-202 F3.1 d e_Per Error on Period
204 I1 --- Cat [1/2] Confidence category (1)
206-207 I2 --- Ncomp [2/14] Number of used PCA components
209-211 A3 --- Object [MS TO BIN PTO] Additional object
qualifier (2)
213 A1 --- GyroSample [Y/N] Star used for gyrochronology sample (3)
215-237 A23 --- FileName Name of the fits file with light curve
in subdirectory fits
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Note (1): Confidence in the obtained period as follows:
1 = high
2 = low
Note (2): Additional object qualifier as follows:
MS = Main sequence
BIN = (possible) binary/contamination
TO = Star around/at Turn-Off
Note (3): gyrochronology sample flag as follows:
Y = period can be considered reliable for gyrochronology
N = otherwise
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Acknowledgements:
David Gruner, dgruner(at)aip.de
(End) Patricia Vannier [CDS] 15-Sep-2020