J/ApJ/879/49 Rotation periods for 171 Gaia members of NGC 6811 (Curtis+, 2019)
A temporary epoch of stalled spin-down for low-mass stars: insights from
NGC6811 with Gaia and Kepler.
Curtis J.L., Agueros M.A., Douglas S.T., Meibom S.
<Astrophys. J., 879, 49 (2019)>
=2019ApJ...879...49C 2019ApJ...879...49C
ADC_Keywords: Clusters, open; Stars, masses; Spectral types; Photometry; Optical
Keywords: open clusters and associations: individual (NGC 6811, Pleiades,
Praesepe) ; stars: evolution ; stars: rotation ; stars: solar-type
Abstract:
Stellar rotation was proposed as a potential age diagnostic that is
precise, simple, and applicable to a broad range of low-mass stars
(≤1M☉). Unfortunately, rotation period (Prot) measurements of
low-mass members of open clusters have undermined the idea that stars
spin down with a common age dependence (i.e., P_rot∝age0.5):
K dwarfs appear to spin down more slowly than F and G dwarfs.
Agueros+ (2018, J/ApJ/862/33) interpreted data for the ∼1.4Gyr-old
cluster NGC 752 differently, proposing that after having converged
onto a slow-rotating sequence in their first 600-700Myr (by the age of
Praesepe), K dwarf Prot stall on that sequence for an extended
period of time. We use data from Gaia DR2 to identify likely
single-star members of the ∼1Gyr-old cluster NGC 6811 with Kepler
light curves. We measure Prot for 171 members, more than doubling
the sample relative to the existing catalog and extending the mass
limit from ∼0.8 to ∼0.6M☉. We then apply a gyrochronology
formula calibrated with Praesepe and the Sun to 27 single G dwarfs in
NGC 6811 to derive a precise gyrochronological age for the cluster of
1.04±0.07Gyr. However, when our new low-mass rotators are included,
NGC 6811's color-Prot sequence deviates away from the naive 1Gyr
projection down to Teff∼4295K (K5V, 0.7M_☉), where it clearly
overlaps with Praesepe's. Combining these data with Prot for other
clusters, we conclude that the assumption that mass and age are
separable dependencies is invalid. Furthermore, the cluster data show
definitively that stars experience a temporary epoch of reduced
braking efficiency where Prot stall, and that the duration of this
epoch lasts longer for lower-mass stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 171 Data for the NGC 6811 benchmark sample
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/PAZh/25/115 : A study of the open cluster NGC 6811 (Glushkova+, 1999)
J/AJ/134/2340 : Praesepe & Coma Berenices cluster membership (Kraus+, 2007)
J/ApJ/695/679 : Stellar rotation in M35 (Meibom+, 2009)
J/MNRAS/408/475 : HATNet Pleiades Rotation Period Catalogue (Hartman+, 2010)
J/ApJ/733/L9 : Stellar rotation for 71 NGC 6811 members (Meibom+, 2011)
J/ApJ/733/115 : Rotation periods and membership in M34 (Meibom+, 2011)
J/other/RMxAA/47.309 : NGC 6811 & NGC 6830 uvby-β photometry (Pena+, 2011)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/AJ/145/134 : RVs of 108 stars in Ruprecht 147 (Curtis+, 2013)
J/AJ/145/7 : UBVRI CCD photom. of the open cluster NGC 6811 (Janes+, 2013)
J/ApJ/776/67 : Rotational tracks (van Saders+, 2013)
J/AJ/148/51 : WIYN Open Cluster. LXI. NGC6819 phot. (Anthony-Twarog+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/other/ApSS/355.267 : NGC 6811 CCD UBVRI photometry (Yontan+, 2015)
J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)
J/ApJ/822/47 : K2 rotation periods for 65 Hyades members (Douglas+, 2016)
J/AJ/152/113 : Pleiades members with K2 LCs. I. Periods (Rebull+, 2016)
J/ApJ/831/11 : KIC 9777062 RVs & NGC6811 asteroseismology (Sandquist+, 2016)
J/ApJ/838/115 : Asteroseismic data of 8 Kepler red giants (Arentoft+, 2017)
J/ApJ/842/83 : Praesepe members rot. periods from K2 LCs (Douglas+, 2017)
J/ApJ/862/33 : Expanded membership cat. for NGC752 (Agueros+, 2018)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diag. (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/171] Sequential running number
5- 12 I8 --- KIC [9095289/10018969] Kepler Input Catalog ID
14- 32 I19 --- Gaia Gaia DR2 Source ID
34- 39 F6.3 mag Gmag [13.3/19] Gaia DR2 G magnitude
41- 45 F5.3 mag BP-RP [0.5/2.1] Gaia BP-RP color index
47- 50 I4 K Teff [3740/6507] Effective temperature (1)
52- 56 F5.3 Msun Mass [0.5/1.3] Mass
58- 59 A2 --- SpT Spectral Type
61- 65 F5.2 d Per [0.6/19] Rotational period (2)
67- 72 F6.4 d e_Per [0.0006/1]? 1σ Uncertainty in Per (3)
74- 75 I2 --- NQ [1/15] Number of Quarters
77- 77 A1 --- f_Seq Star code (4)
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Note (1): Effective temperature calculated with an empirical color-temperature
relation.
Note (2): The rotational period is measured for every available Quarter
between 2 and 16 with Lomb-Scargle periodograms.
Note (3): The standard deviation is adopted as the uncertainty in Prot; it is
omitted when NQ=1.
Note (4): Star code as follows:
R = rapid (2 occurrences);
S = slow (8 occurrences);
Y = typical stars are consistent with the cluster sequence (161 occurrences).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Dec-2020