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Power of wavelets in analyses of transit and phase curves in the presence of stellar variability and instrumental noise. I. Method and validation

Csizmadia, Szilard and Smith, Alexis M S and Kálmán, Szilard and Cabrera Perez, Juan and Klagyivik, Peter and Chaushev, Alexander and Lam, Wai Fun (2023) Power of wavelets in analyses of transit and phase curves in the presence of stellar variability and instrumental noise. I. Method and validation. Astronomy & Astrophysics, 675, A106. EDP Sciences. doi: 10.1051/0004-6361/202141302. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/full_html/2023/07/aa41302-21/aa41302-21.html


Context. Stellar photometric variability and instrumental effects, such as cosmic ray hits, data discontinuities, data leaks, instrument aging, and so on, lead to difficulties in the characterisation of exoplanets. Therefore, they can impact the accuracy and precision of the modelling and the detectability of their transits, occultations, and phase curves. Aims. This paper is aimed at improving the transit, occultation, and phase-curve modelling in the presence of strong stellar variability and instrumental noise. To this end, we invoke the wavelet formulation. Methods. We explored the capabilities of the software package Transit and Light Curve Modeller (TLCM). It is able to perform (1) a joint radial-velocity and light-curve fit or (2) a light curve-only fit. It models the transit, occultation, beaming, ellipsoidal, and reflection effects in the light curves (including the gravity-darkening effect). Here, the red noise, stellar variability, and instrumental effects were modelled via wavelets. The wavelet fit was constrained by prescribing that the final white noise level must be equal to the average of the uncertainties of the photometric data points. This helps to avoid overfitting and regularises the noise model. The approach was tested by injecting synthetic light curves into short-cadence Kepler data and modelling them. Results. The method performs well over a certain signal-to-noise (S/N) ratio. We provide limits in terms of the S/N for every studied system parameter that is needed for accurate parameter retrieval. The wavelet approach is able to manage and remove the impact of data discontinuities, cosmic ray events, and long-term stellar variability and instrument ageing, as well as short-term stellar variability, pulsation, and flares (among others). Conclusions. We conclude that precise light-curve models combined with the wavelet method and with well-prescribed constraints on the white noise are able to retrieve the planetary system parameters, even in the presence of strong stellar variability and instrumental noise, including data discontinuities.

Item URL in elib:https://elib.dlr.de/189563/
Document Type:Article
Title:Power of wavelets in analyses of transit and phase curves in the presence of stellar variability and instrumental noise. I. Method and validation
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Csizmadia, SzilardUNSPECIFIEDhttps://orcid.org/0000-0001-6803-9698UNSPECIFIED
Smith, Alexis M SUNSPECIFIEDhttps://orcid.org/0000-0002-2386-4341UNSPECIFIED
Kálmán, SzilardKonkoly Observatory, Research Centre for Astronomy and Earth Sciences; MTA-ELTE Exoplanet Research Group; ELTE Eötvös Loránd University; CSFK, MTA Centre of ExcellenceUNSPECIFIEDUNSPECIFIED
Cabrera Perez, JuanUNSPECIFIEDhttps://orcid.org/0000-0001-6653-5487UNSPECIFIED
Klagyivik, PeterUNSPECIFIEDhttps://orcid.org/0000-0003-0700-6176UNSPECIFIED
Chaushev, AlexanderCenter for Astronomy and Astrophysics, TU Berlin, Hardenbergstr. 36, 10623 Berlin, GermanyCenter for Astronomy and Astrophysics, TU Berlin, GermanyUNSPECIFIEDUNSPECIFIED
Date:7 July 2023
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:A106
Publisher:EDP Sciences
Keywords:Methods: data analysis – Planets and satellites: atmospheres – Planets and satellites: interiors – Planets and satellites: general – Techniques: photometric
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project PLATO - PMC and Science
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Extrasolar Planets and Atmospheres
Deposited By: Csizmadia, Szilard
Deposited On:28 Aug 2023 09:00
Last Modified:19 Sep 2023 08:58

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