Query : 2019A&A...627A..86B

2019A&A...627A..86B - Astronomy and Astrophysics, volume 627A, 86-86 (2019/7-1)

Analysis of putative exoplanetary signatures found in light curves of two sdBV stars observed by Kepler.


Abstract (from CDS):

Context. We investigate the validity of the claim that invokes two extreme exoplanetary system candidates around the pulsating B-type subdwarfs KIC 10001893 and KIC 5807616 from the primary Kepler field. Aims. Our goal was to find characteristics and the source of weak signals that are observed in these subdwarf light curves. Methods. To achieve this, we analyzed short- and long-cadence Kepler data of the two stars by means of a Fourier transform and compared the results to Fourier transforms of simulated light curves to which we added exoplanetary signals. The long-cadence data of KIC 10001893 were extracted from CCD images of a nearby star, KIC 10001898, using a point spread function reduction technique. Results. It appears that the amplitudes of the Fourier transform signals that were found in the low-frequency region depend on the methods that are used to extract and prepare Kepler data. We demonstrate that using a comparison star for space telescope data can significantly reduce artifacts. Our simulations also show that a weak signal of constant amplitude and frequency, added to a stellar light curve, conserves its frequency in Fourier transform amplitude spectra to within 0.03µHz. Conclusions. Based on our simulations, we conclude that the two low-frequency Fourier transform signals found in KIC 5807616 are likely the combined frequencies of the lower amplitude pulsating modes of the star. In the case of KIC 10001893, the signal amplitudes that are visible in the light curve depend on the data set and reduction methods. The strongest signal decreases significantly in amplitude when KIC 10001898 is used as a comparison star. Finally, we recommend that the signal detection threshold is increased to 5σ (or higher) for a Fourier transform analysis of Kepler data in low-frequency regions.

Abstract Copyright: © ESO 2019

Journal keyword(s): subdwarfs - asteroseismology - planetary systems

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 LBQS 1145+0145 WD* 11 48 33.6297189672 +01 28 59.420446860           DB 175 0
2 GD 358 WD* 16 47 18.3925183824 +32 28 32.862804384 12.511 13.530 13.653 13.752 13.852 DB2 348 0
3 Kepler-429 HS* 19 09 33.4136944848 +46 59 04.108493616           sdB 30 0
4 UCAC4 685-065910 * 19 09 33.7280778168 +46 59 11.100908328   14.964 14.834 14.899   ~ 2 0
5 2MASS J19343993+4758117 HS* 19 34 39.9403400856 +47 58 11.532614808           sdB 27 1
6 Kepler-70 HS* 19 45 25.4745687168 +41 05 33.882248544 13.80 14.71 14.87 15.43 15.72 sdB 71 1

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