J/A+A/605/A111 Surface rotation of Kepler red giant stars (Ceillier+, 2017)
Surface rotation of Kepler red giant stars.
Ceillier T., Tayar J., Mathur S., Salabert D., Garcia R.A., Stello D.,
Pinsonneault M.H., van Saders J., Beck P.G., Bloemen S.
<Astron. Astrophys. 605, A111 (2017)>
=2017A&A...605A.111C 2017A&A...605A.111C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, giant ; Effective temperatures ;
Stars, masses
Keywords: stars: rotation - stars: activity - stars: evolution
Abstract:
Kepler allows the measurement of starspot variability in a large
sample of field red giants for the first time. With a new method that
combines autocorrelation and wavelet decomposition, we measure 361
rotation periods from the full set of 17,377 oscillating red giants in
our sample. This represents 2.08% of the stars, consistent with the
fraction of spectroscopically detected rapidly rotating giants in the
field. The remaining stars do not show enough variability to allow us
to measure a reliable surface rotation period. Because the stars with
detected rotation periods have measured oscillations, we can infer
their global properties, e.g. mass and radius, and quantitatively
evaluate the predictions of standard stellar evolution models as a
function of mass. Consistent with results for cluster giants, when we
consider only the 4881 intermediate-mass stars, M>2.0M☉from our
full red giant sample, we do not find the enhanced rates of rapid
rotation one would expect from angular momentum conservation. We
therefore suggest that either enhanced angular momentum loss or radial
differential rotation must be occurring in these stars. Finally, when
we examine the 575 low-mass (M<1.1M☉) red clump stars in our
sample, which we would have expected to exhibit slow (non-detectable)
rotation, 15% of them actually have detectable rotation. This suggests
a high rate of interactions and stellar mergers on the red giant
branch.
Description:
As only a few red giants are supposed to exhibit light curve
modulations due to star spots, we use for this work the largest sample
of identified red giants observed by the Kepler satellite so far. It
is composed of 17,377 pulsating stars including those already known
from previous works (e.g. Huber et al. 2010ApJ...723.1607H 2010ApJ...723.1607H; Hekker et
al. 2011MNRAS.414.2594H 2011MNRAS.414.2594H; Mosser et al. 2012A&A...537A..30M 2012A&A...537A..30M; Stello et
al. 2013, Cat. J/ApJ/765/L41; Mathur et al. 2016, Cat. J/ApJ/827/50).
Table 1 is giving the stars with validated rotation periods.
Table 2 is giving the stars showing rotational modulation in their
light curve, but probably due to pollution from a nearby star.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 361 Stars with validated rotation periods
table2.dat 92 170 Stars showing rotational modulation in their
light curve, but probably due to pollution
from a nearby star
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJ/765/L41 : Asteroseismic classification of KIC objects (Stello+, 2013)
J/ApJ/827/50 : Kepler faint red giants (Mathur+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler ID
10- 15 F6.2 uHz numax Frequency of maximum power
17- 21 F5.2 uHz e_numax ?=-1 Error on numax
23- 27 F5.2 uHz dnu Large frequency separation
29- 33 F5.2 uHz e_dnu Error on dnu
35- 38 I4 K Teff Effective Temperature
40- 42 I3 K e_Teff ?=-1 Error on Teff
44- 48 F5.2 [cm/s2] logg Logarithm of the surface gravity
50- 54 F5.2 [cm/s2] e_logg ?=-1 Error on logg
56- 60 F5.2 Msun M Mass of the star
62- 66 F5.2 Msun e_M ?=-1 Error on M
68- 73 F6.2 d Prot Surface Rotation Period
75- 79 F5.2 d e_Prot Error on Prot
81- 84 F4.2 --- Crowding Crowding of the aperture (G1)
86- 90 F5.2 d Tcrit Critical Period
92- 96 F5.2 km/s Vsini Projected velocity
98-101 F4.2 km/s e_Vsini Error on Vsini
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC Kepler ID
10- 15 F6.2 muHz numax Frequency of maximum power
17- 21 F5.2 muHz e_numax Error on numax
23- 27 F5.2 muHz dnu Large frequency separation
29- 32 F4.2 muHz e_dnu Error on dnu
34- 38 I5 K Teff Effective Temperature
40- 42 I3 K e_Teff ?=-1 Error on Teff
44- 48 F5.2 [cm/s2] logg Logarithm of the surface gravity
50- 54 F5.2 [cm/s2] e_logg ?=-1 Error on logg
56- 60 F5.2 Msun M Mass of the star
62- 66 F5.2 Msun e_M ?=-1 Error on M
68- 73 F6.2 d Prot Surface Rotation Period
75- 79 F5.2 d e_Prot Error on Prot
81- 84 F4.2 --- Crowding Crowding of the aperture (G1)
86- 90 F5.2 d Tcrit Critical Period
92 I1 --- Flag [1/2] Value of the flag (2)
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Note (2): Flag as follows:
1 = star has been discarded because of a low crowding value
2 = star has been discarded because the ratio Prot/Tcrit is too small
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Global notes:
Note (G1): The crowding value represents the amount of the integrated flux
belonging to the targeted star. Hence, it is equal to 1 when only the targeted
star is in the aperture.
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Acknowledgements:
R.A. Garcia, rgarcia(at)cea.fr
(End) R.A. Garcia [Lab. AIM - CEA-DSM - CNRS], P. Vannier [CDS] 25-Jul-2017