J/ApJ/851/116 Long-term variability of Kepler sun-like stars (Montet+, 2017)
Long-term photometric variability in Kepler full-frame images: magnetic cycles
of Sun-like stars.
Montet B.T., Tovar G., Foreman-Mackey D.
<Astrophys. J., 851, 116 (2017)>
=2017ApJ...851..116M 2017ApJ...851..116M
ADC_Keywords: Stars, G-type; Photometry; Optical
Keywords: methods: data analysis ; stars: activity ; stars: solar-type ;
techniques: photometric
Abstract:
Photometry from the Kepler mission is optimized to detect small,
short- duration signals like planet transits at the expense of
long-term trends. This long-term variability can be recovered in
photometry from the full-frame images (FFIs), a set of calibration
data collected approximately monthly during the Kepler mission. Here
we present f3, an open-source package to perform photometry on the
Kepler FFIs in order to detect changes in the brightness of stars in
the Kepler field of view over long time baselines. We apply this
package to a sample of 4000 Sun-like stars with measured rotation
periods. We find that ∼10% of these targets have long-term variability
in their observed flux. For the majority of targets, we find that the
luminosity variations are either correlated or anticorrelated with the
short-term variability due to starspots on the stellar surface. We
find a transition between anticorrelated (starspot-dominated)
variability and correlated (facula-dominated) variability between
rotation periods of 15 and 25 days, suggesting the transition between
the two modes is complete for stars at the age of the Sun. We also
identify a sample of stars with apparently complete cycles, as well as
a collection of short-period binaries with extreme photometric
variation over the Kepler mission.
Description:
In this paper, we develop a method to recover long-term brightness
variations for stars in the Kepler field from FFI data, building on
previous work (Montet & Simon 2016ApJ...830L..39M 2016ApJ...830L..39M).
The observations in this paper are taken from the 53 Full-frame Images
(FFIs) collected by Kepler during its primary mission. All FFIs are
publicly available and contain observations of approximately 4.5
million objects in the telescope's field of view. We downloaded all
FFIs from the Mikulski Archive for Space Telescopes (MAST).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 48 463 Stars with observed long-term variability during
the Kepler mission
table2.dat 18 28 Stars with apparently complete magnetic cycles
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/AJ/138/312 : Activity of bright solar analogs (Hall+, 2009)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/ApJS/199/30 : Effective temperatures for KIC stars (Pinsonneault+, 2012)
J/ApJ/763/L26 : SMARTS observations of eps Eridani (Metcalfe+, 2013)
J/A+A/557/L10 : Rotation periods of 12000 Kepler stars (Nielsen+, 2013)
J/MNRAS/431/966 : Transiting planet WASP-50b (Tregloan-Reed+, 2013)
J/ApJS/211/2 : Revised properties of Q1-16 Kepler targets (Huber+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/ApJ/812/12 : S-index and Stroemgren LC of HD30495 (Egeland+, 2015)
J/ApJ/813/100 : Deep GALEX NUV survey of the Kepler field. I. (Olmedo+, 2015)
J/MNRAS/452/2127 : Fundamental param. of Kepler stars (Silva Aguirre+, 2015)
J/ApJ/818/43 : Stellar surface gravity measures of KIC stars (Bastien+, 2016)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/A+A/592/A156 : The Solar Twin Planet Search. IV. (dos Santos+, 2016)
J/ApJ/818/34 : Radial velocity monitoring of 5 FGK stars (Endl+, 2016)
J/ApJ/838/25 : Hectochelle spectroscopy for 776 Kepler stars (Guo+, 2017)
J/A+A/603/A52 : Activity cycles in 3203 Kepler stars (Reinhold+, 2017)
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 [2013503/12690265] Kepler Input Catalog identifier
10- 15 F6.3 d Prot [0.3/65.2] Rotation period from
McQuillan+ (2014, J/ApJS/211/24)
17- 22 F6.3 mag Kpmag [9.5/16] Kepler Input Catalog magnitude
from Brown+ (2011, J/AJ/142/112).
24- 28 F5.3 mag B-V [0.5/0.8]? The (B-V) color index from
Everett+ (2012PASP..124..316E 2012PASP..124..316E)
30- 34 F5.2 --- Scat [0.4/41.6] Scatter in measured FFI photometry;
parts per thousand
36- 42 A7 --- Var Variability if determinable (Spots or Faculae) (1)
44- 48 A5 --- Notes Additional comment(s) (2)
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Note (1): Primary driver of full-frame image (FFI) variability.
Note (2): Note as follows:
1 = Short-period binary
2 = Apparent complete cycle observed in full-frame image (FFI) data
3 = GALEX-detected UV source (Olmedo+ 2015, J/ApJ/813/100)
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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 [2694810/12417799] Kepler Input Catalog identifier
10 A1 --- f_KIC [a] a: Cycle observed and period inferred
from the photometric activity index, Sph,
variability
12-14 F3.1 % SemiAmp [0.1/2]? Semiamplitude
16-18 F3.1 yr Per [1.6/4.5] Period
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Jul-2018