J/ApJS/237/17 Temporal frequency shifts in 87 Kepler stars (Santos+, 2018)
Signatures of magnetic activity in the seismic data of solar-type stars
observed by Kepler.
Santos A.R.G., Campante T.L., Chaplin W.J., Cunha M.S., Lund M.N.,
Kiefer R., Salabert D., Garcia R.A., Davies G.R., Elsworth Y., Howe R.
<Astrophys. J. Suppl. Ser., 237, 17 (2018)>
=2018ApJS..237...17S 2018ApJS..237...17S
ADC_Keywords: Asteroseismology; Stars, G-type
Keywords: asteroseismology ; methods: data analysis ; stars: activity ;
stars: oscillations ; stars: solar-type
Abstract:
In the Sun, the frequencies of the acoustic modes are observed to vary
in phase with the magnetic activity level. These frequency variations
are expected to be common in solar-type stars and contain information
about the activity-related changes that take place in their interiors.
The unprecedented duration of Kepler photometric time-series provides
a unique opportunity to detect and characterize stellar magnetic
cycles through asteroseismology. In this work, we analyze a sample of
87 solar-type stars, measuring their temporal frequency shifts over
segments of 90 days. For each segment, the individual frequencies are
obtained through a Bayesian peak-bagging tool. The mean frequency
shifts are then computed and compared with: (1) those obtained from a
cross-correlation method; (2) the variation in the mode heights; (3) a
photometric activity proxy; and (4) the characteristic timescale of
the granulation. For each star and 90-day sub-series, we provide mean
frequency shifts, mode heights, and characteristic timescales of the
granulation. Interestingly, more than 60% of the stars show evidence
for (quasi-)periodic variations in the frequency shifts. In the
majority of the cases, these variations are accompanied by variations
in other activity proxies. About 20% of the stars show mode
frequencies and heights varying approximately in phase, in opposition
to what is observed for the Sun.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 128 87 Stellar parameters of the target sample composed
of 87 Kepler solar-type stars
table2.dat 121 1854 Peak-bagging for the Kepler stars in the sample
--------------------------------------------------------------------------------
See also:
J/A+A/508/L17 : Abundances in solar analogs (Ramirez+, 2009)
J/ApJS/199/30 : Temperature scale for KIC stars (Pinsonneault+, 2012)
J/ApJ/767/127 : Asteroseismic solutions for 77 Kepler stars (Huber+, 2013)
J/ApJ/775/L11 : Stellar rotation periods for KOIs (McQuillan+, 2013)
J/ApJ/763/L26 : SMARTS observations of eps Eridani (Metcalfe+, 2013)
J/MNRAS/436/1883 : Properties of KOI host stars (Walkowicz+, 2013)
J/ApJ/787/110 : SAGA: Stromgren survey of seismic KIC (Casagrande+, 2014)
J/ApJS/210/1 : Asteroseismic study of solar-type stars (Chaplin+, 2014)
J/ApJ/789/154 : Kepler-10 RV measurements by HARPS-N (Dumusque+, 2014)
J/A+A/572/A34 : Pulsating solar-like stars in Kepler (Garcia+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJS/215/19 : APOKASC catalog of Kepler red giants (Pinsonneault+, 2014)
J/MNRAS/446/2959 : Asterosismology for solar analogues (Davies+, 2015)
J/ApJ/812/12 : S-index and Stroemgren LC of HD30495 (Egeland+, 2015)
J/A+A/578/A137 : Solar acoustic modes in period 1996-2014 (Salabert+, 2015)
J/MNRAS/452/2127 : Fundamental param. of Kepler stars (Silva Aguirre+, 2015)
J/ApJ/835/172 : Kepler asteroseismic LEGACY. I. Oscillations (Lund+, 2017)
J/ApJ/835/173 : Kepler asteroseismic LEGACY. II. (Silva Aguirre+, 2017)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC [1435467/12317678] Kepler Input Cat. identifier
10- 13 I4 --- KOI [2/3158]? KOI star number
15- 19 F5.2 mag Kpmag [5.8/12.3] Kepler magnitude
21- 31 A11 --- Q Quarters (1)
33- 38 F6.1 uHz numax [884.7/4660] Frequency of the maximum power (2)
40- 44 F5.1 uHz e_numax [2.7/280] Negative uncertainty on numax
46- 50 F5.1 uHz E_numax [2.8/280] Positive uncertainty on numax
52- 58 F7.3 uHz Delnu [48.4/179.7] Large frequency separation (2)
60- 64 F5.3 uHz e_Delnu [0.01/2.5] Negative uncertainty on Delnu
66- 70 F5.3 uHz E_Delnu [0.01/2.5] Positive uncertainty on Delnu
72- 75 I4 K Teff [5046/6642] Effective temperature
77- 79 I3 K e_Teff [50/180] Negative uncertainty on Teff
81 I1 K E_Teff [1/8] Positive uncertainty on Teff
83- 87 F5.2 [Sun] [Fe/H] [-1/0.4] Metallicity
89- 92 F4.2 [Sun] e_[Fe/H] [0.02/0.2] [Fe/H] uncertainty
94 I1 --- r_[Fe/H] [1/8] Reference for [Fe/H] and Teff (3)
96-100 F5.3 [cm/s2] logg [3.9/4.6] Log of gravity surface from
Silva Aguirre+ (2015, J/MNRAS/452/2127 and
2017, J/ApJ/835/173)
102-106 F5.3 [cm/s2] e_logg [0.002/0.02] Negative uncertainty on logg
108-112 F5.3 [cm/s2] E_logg [0.002/0.02] Positive uncertainty on logg
114-119 F6.3 d Prot [0.9/35.4]? Rotational period
121-125 F5.3 d e_Prot [0.001/6]? Prot uncertainty
127-128 I2 --- r_Prot [9/16]? Reference for Prot (3)
--------------------------------------------------------------------------------
Note (1): Each quarter corresponds to one-quarter of Kepler's year (∼372.5d).
Note (2): Frequency of the maximum power (νmax) and large frequency
separation (Δν) are from Davies+ (2016MNRAS.456.2183D 2016MNRAS.456.2183D) or
Lund+ (2017, J/ApJ/835/172).
Note (3): Reference as follows:
1 = Lund et al. (2017, J/ApJ/835/172)
2 = Silva Aguirre et al. (2015, J/MNRAS/452/2127)
3 = Chaplin et al. (2014, J/ApJS/210/1)
4 = Casagrande et al. (2014, J/ApJ/787/110)
5 = Pinsonneault et al. (2012, J/ApJS/199/30)
6 = Pinsonneault et al. (2014, J/ApJS/215/19)
7 = Huber et al. (2013, J/ApJ/767/127)
8 = Ramirez et al. (2009, J/A+A/508/L17)
9 = Garcia et al. (2014, J/A+A/572/A34)
10 = McQuillan et al. (2014, J/ApJS/211/24)
11 = Ceillier et al. (2016MNRAS.456..119C 2016MNRAS.456..119C)
12 = McQuillan et al. (2013, J/ApJ/775/L11)
13 = Walkowicz & Basri (2013, J/MNRAS/436/1883)
14 = Karoff et al. (2013MNRAS.433.3227K 2013MNRAS.433.3227K)
15 = Dumusque et al. (2014, J/ApJ/789/154)
16 = Davies et al. (2015, J/MNRAS/446/2959).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [KIC]
4- 11 I8 --- KIC [1435467/12317678] Kepler Input Cat. number (1)
13- 14 I2 --- Order1 [15/24] First central order
16- 17 I2 --- Order2 [19/28] Fifth central order
18- 18 A1 --- f_shiftsCC [*] Flag on shiftsCC (2)
20- 23 I4 d Time [45/1450] Time of the sub-series midpoint
25- 28 F4.2 --- DC [0.01/1]? Duty cycle of the sub-series
30- 34 F5.1 s taug [133/667]? Characteristic granulation timescale
36- 40 F5.1 s e_taug [0/812]? Uncertainty in taug
42- 46 F5.2 uHz shift0 [-2.2/2.1]? Mean frequency shifts for l=0 (3)
48- 51 F4.2 uHz e_shift0 [0.05/1.1]? Uncertainty in shift0
53- 57 F5.2 uHz shift1 [-1.3/1.6]? Mean frequency shifts for l=1 (3)
59- 62 F4.2 uHz e_shift1 [-1.3/1.1]? Uncertainty in shift1
64- 68 F5.2 uHz shift2 [-1.9/1.8]? Mean frequency shifts for l=2 (3)
70- 73 F4.2 uHz e_shift2 [0.05/2]? Uncertainty in shift2
75- 79 F5.2 uHz [-1.4/1.6]? Mean frequency shifts, combining
l=0 and l=1 (3)
81- 84 F4.2 uHz e_ [0.04/0.7]? Uncertainty in
86- 90 F5.2 --- logS [-1/3.7]? Mean logarithmic mode heights (3)
92- 95 F4.2 --- e_logS [0.08/1.2]? Uncertainty in logS
97-101 F5.2 uHz shiftsCC [-0.9/1.6]? Frequency shifts obtained with
CC method (4)
103-107 F5.2 uHz e_shiftsCC [0.06/16.6]? Uncertainty in shiftsCC
109-121 F13.5 d JD ? Julian date of the observation
(updated column)
--------------------------------------------------------------------------------
Note (1): KIC 8938264 is very likely a misprint for KIC 8938364;
corrected at CDS.
Note (2):
* = frequency shifts from the cross-correlation method were
obtained with 180-d sub-series.
Note (3): Mean frequency shifts and logarithmic mode heights were obtained
through the Bayesian peak-bagging analysis described in Section 2.
Only the five central radial orders (Order1 - Order2) were used
to compute the mean parameters.
Note (4): The frequency shifts were obtained with the cross-correlation (CC)
method presented in Kiefer et al. (2017A&A...598A..77K 2017A&A...598A..77K).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
The Julian Date in Table 2 have been sent by the author.
Acknowledgements:
Angela Santos [spacescience.org]
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Sep-2018