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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)


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Estrela, Raissa ; Valio, Adriana
Total Authors: 2
Document type: Journal article
Source: ASTROPHYSICAL JOURNAL; v. 831, n. 1 NOV 1 2016.
Web of Science Citations: 8

The stellar magnetic field plays a crucial role in the star internal mechanisms, as in the interactions with its environment. The study of starspots provides information about the stellar magnetic field. and can characterize the cycle. Moreover, the analysis of solar-type stars is also useful to shed light onto the origin of the solar magnetic field. The objective of this work is to characterize the magnetic activity of stars. Here, we studied two solar-type stars, Kepler-17 and Kepler-63, using two methods to estimate the magnetic cycle length. The first one characterizes the spots (radius, intensity, and location) by fitting the small variations in the light curve of a star caused by the occultation of a spot during a planetary transit. This approach yields the number of spots present in the stellar surface and the flux deficit subtracted from the star by their presence during each transit. The second method estimates the activity from the excess in the residuals of the transit light. curves. This excess is obtained by subtracting a spotless model transit from the light curve. and then integrating all the residuals during the transit. The presence of long-term periodicity is estimated in both time series. With the first method, we obtained P-cycle = 1.12 +/- 0.16 year (Kepler-17) and P-cycle = 1.27 +/- 0.16 year (Kepler-63), and for the second approach the values are 1.35 +/- 0.27 year and 1.27 +/- 0.12 year, respectively. The results of both methods agree with each other and confirm their robustness. (AU)

FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Research Projects - Thematic Grants