J/MNRAS/469/2907 Kepler-410Ab transit timing variations (Gajdos+, 2017)
Transit Timing Variations in the system Kepler-410Ab.
Gajdos P., Parimucha S., Hambalek L., Vanko M.
<Mon. Not. R. Astron. Soc. 469, 2907 (2017)>
=2017MNRAS.469.2907G 2017MNRAS.469.2907G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry
Keywords: photometry - stars: binaries -
planets and satellites: individual (Kepler-410Ab)
Abstract:
For the determination of the individual times of transit we used
short- cadence (sampled every 58.8 seconds) de-trended data
(PDCSAP_FLUX) from quarters Q1 to Q17, provided by the NASA Exoplanet
Archive. As a first step, we extracted parts of the LC around detected
transits using the ephemeris given in Van Eylen et al.
(2014ApJ...782...14V 2014ApJ...782...14V), where we took an interval 0.2 days around the
computed transit time (the interval size is approximately double the
transit duration). To remove additional residual trends caused by the
stellar activity and instrumental long-term photometric variation, we
fitted the out-of-transit part of LC by a second-order polynomial
function. Then we subtracted 8% flux contamination from the wide
companion Kepler-410B, according to calculations of Van Eylen et al.
(2014ApJ...782...14V 2014ApJ...782...14V).
All individual parts of the LC with transits were stacked together to
obtain the template of the transit.
The stacked LC was fitted by our software implementation of Mandel &
Agol (2002ApJ...580L.117M 2002ApJ...580L.117M) model, where we used theMarkov Chain Monte
Carlo (MCMC) simulation method for the determination of transit
parameters. This method takes into account individual errors of Kepler
observations and gives a realistic and statistically significant
estimate of parameter errors. As a starting point for the MCMC
fitting, we used the physical parameters of the planet given in Van
Eylen et al. (2014ApJ...782...14V 2014ApJ...782...14V). We have adopted a fixed value
a=0.1226AU. We have used a quadratic model of limb darkening with
starting values of coefficients from Sing (2010, Cat. J/A+A/510/A21).
We ran the MCMC simulation with 106 steps.
We have repeated the MCMC simulation with the previous solution as the
starting point on each of 70 individual transit intervals, and let
only the time of transit to update. The new values were used to
improve the linear ephemeris and to construct a new O-C diagram. The
combined light curve stacked using a linear ephemeris is affected by
relatively large amplitude of O-C time shifts. To correct this effect,
we used iterative procedure that takes the best-fit O-C values into
account. Afterwards, a new stacked light curve was constructed and a
new MCMC transit solution was calculated, subsequently a new ephemeris
and O-C values were determined. This process was repeated three times
until a convergent solution was reached.
Description:
Barycentric transit times of Kepler-410Ab, with their uncertainties,
chi2 and chi2/n statistics (n - the number of data points in the
fit).
Objects:
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RA (2000) DE Designation(s)
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18 52 36.16 +45 08 23.4 Kepler-410Ab = KOI-42.01
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 57 70 Barycentric transit times
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See also:
J/ApJ/790/31 : Transit times and durations of three KOIs (Nesvorny+, 2014)
J/A+A/577/A109 : Transit times of Qatar-1b (Maciejewski+, 2015)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 F15.7 d Time Observed barycentric times of transits (BJD)
20- 28 F9.7 d e_Time Uncertainty of transits times
33- 40 F8.3 --- chi2 Chi2 error of fitting individual transit
45- 49 F5.3 --- chi2/n Chi2/n error
55- 57 I3 --- n Number of data points of individual transit
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Acknowledgements:
Pavol Gajdos,
(End) Pavol Gajdos [UPJS, Slovakia], Patricia Vannier [CDS] 02-Jun-2017