J/other/NatAs/5.707 Dwarf stars asteroseismic rotation rates (Hall+, 2021)
Weakened magnetic braking supported by asteroseismic rotation rates of
Kepler dwarfs.
Hall O.J., Davies G.R., van Saders J., Nielsen M.B., Lund M.N.,
Chaplin W.J., Garcia R.A., Amard L., Breimann A.A., Khan S., See V.,
Tayar J.
<Nature Astronomy, 5, 707-714 (2021)>
=2021NatAs...5..707H 2021NatAs...5..707H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, G-type ; Stars, variable ; Stars, ages ; Stars, masses
Keywords: asteroseismology - solar-like oscillators - stellar rotation
Abstract:
Studies using asteroseismic ages and rotation rates from star-spot
rotation have indicated that standard age-rotation relations may break
down roughly half way through the main sequence lifetime, a phenomenon
referred to as weakened magnetic braking. Although rotation rates from
spots can be difficult to determine for older, less active stars,
rotational splitting of asteroseismic oscillation frequencies can
provide rotation rates for both active and quiescent stars, and so can
confirm whether this effect really takes place on the main sequence.
We obtained asteroseismic rotation rates of 91 main sequence stars
showing high signal-to-noise modes of oscillation. Using these new
rotation rates, along with effective temperatures, metallicities and
seismic masses and ages, we built a hierarchical Bayesian mixture
model to determine whether the ensemble more closely agreed with a
standard rotational evolution scenario, or one where weakened magnetic
braking takes place. The weakened magnetic braking scenario was found
to be 98.4% more likely for our stellar ensemble, adding to the
growing body of evidence for this stage of stellar rotational
evolution. This work presents a large catalogue of seismic rotation
rates for stars on the main sequence, which opens up possibilities for
more detailed ensemble analysis of rotational evolution with Kepler.
Description:
Parameters for the 94 stars for which seismic rotation rates were
obtained in the paper. Temperatures (Teff), age, mass,
metallicity ([Fe/H]) and surface gravity (log(g)) are adopted from the
LEGACY (L, Lund et al., 2017ApJ...835..172L 2017ApJ...835..172L, Silva Aguirre et al.,
2017ApJ...836..173S 2017ApJ...836..173S) and 'Kages' (K, Silva Aguirre et al.,
2015MNRAS.452.2127S 2015MNRAS.452.2127S, Davies et al., 2016MNRAS.456.2183D 2016MNRAS.456.2183D) catalogues,
as listed in the Source column. Projected splitting (νssin(i)),
inclination angle (i) and asteroseismic rotation (P) are from the
paper. Uncertainties were taken using the 15.9th and 84.1st
percentiles of posterior distributions on the parameters, which are
frequently asymmetrical in linear space. Reported values are the
median of the posterior distributions. For parameters with no direct
posterior samples (e.g. rotation) the full posterior samples were
transformed before taking the summary statistics. The stellar type
denotes whether a star is roughly classified as belonging to the main
sequence (MS), Sub-Giants (SG) or 'hot' stars (H).
The flags indicate the following:
0; no issues, used in the gyrochronology analysis.
1; has either a number of effective samples neff<1000 for the
asteroseismic splitting, or Gelman-Rubin convergence metric of
R>1.1, indicating that rotation measurements for these stars
are less robust than those with a flag of 0.
2; was found to strongly disagree with multiple literature values,
excluded from the gyrochronology analysis.
3; fell outside the model range of the stellar models, and were
therefore not used in the gyrochronology analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 402 94 Asteroseismic rotation rates
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Index [0/93] Sequential number
4- 11 I8 --- KIC Kepler Input Catalog identifier
13- 16 I4 K Teff Effective temperature
18- 20 I3 K e_Teff rms uncertainty on Teff
22- 40 F19.16 Gyr Age Age
42- 59 F18.16 Gyr e_Age Error on Age (lower value)
61- 78 F18.16 Gyr E_Age Error on Age (upper value)
80- 97 F18.16 Msun Mass Mass
99-118 F20.18 Msun e_Mass Error on Mass (lower value)
120-139 F20.18 Msun E_Mass Error on Mass (upper value)
141-145 F5.2 [Sun] [Fe/H] Metallicity
147-150 F4.2 [Sun] e_[Fe/H] rms uncertainty on Metallicity
152-169 F18.16 [cm/s2] logg Log surface gravity
171-190 F20.18 [cm/s2] e_logg Error on Log surface gravity (lower value)
192-211 F20.18 [cm/s2] E_logg Error on Log surface gravity (upper value)
213-231 F19.17 uHz nussini Projected rotational splitting
233-252 F20.18 uHz e_nussini Error on Projected rotational splitting
(lower value)
254-273 F20.18 uHz E_nussini Error on Projected rotational splitting
(upper value)
275-292 F18.15 deg i Inclination angle
294-312 F19.16 deg e_i Error on Inclination angle (lower value)
314-332 F19.16 deg E_i Error on Inclination angle (upper value)
334-352 F19.16 d P Rotation rate
354-373 F20.17 d e_P Error on Rotation rate (lower value)
375-395 F21.18 d E_P Error on Rotation rate (upper value)
397 I1 --- Flag [0/3] Quality flag for rotation rate (1)
399-400 A2 --- Type [MS SG H] Estimated evolutionary state (2)
402 A1 --- Source [KL] Source for Teff, Age, Mass, logg
and [Fe/H] (3)
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Note (1): Quality flag for rotation rate as follows:
0 = no issues, used in the gyrochronology analysis
1 = has either a number of effective samples neff<1000 for the asteroseismic
splitting, or Gelman-Rubin convergence metric of R>1.1, indicating that
rotation measurements for these stars are less robust than those
with a flag of 0
2 = was found to strongly disagree with multiple literature values,
excluded from the gyrochronology analysis
3 = fell outside the model range of the stellar models, and were
therefore not used in the gyrochronology analysis
Note (2): Estimated evolutionary state as follows:
MS = main sequence star
SG = sub-giants star
H = 'hot' stars
Note (3): References as follows:
K = Kages, Silva Aguirre et al., 2015MNRAS.452.2127S 2015MNRAS.452.2127S and
Davies et al. (2016MNRAS.456.2183D 2016MNRAS.456.2183D)
L = LEGACY, Lund et al., 2017ApJ...835..172L 2017ApJ...835..172L and
Silva Aguirre et al., 2017ApJ...836..173S 2017ApJ...836..173S)
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Acknowledgements:
Oliver Hall, oliver.hall(at)esa.int
(End) Patricia Vannier [CDS] 07-May-2021