author = "Almeida, L. A. and Almeida, Leandro de and Damineli, A. and 
                         Rodrigues, Cl{\'a}udia Vilega and Castro, M. and Lopes, C. E. 
                         Ferreira and Jablonski, Francisco Jos{\'e} and Nascimento 
                         J{\'u}nior, J. D. do and Pereira, M. G.",
          affiliation = "{Universidade Federal do Rio Grande do Norte (UFRN)} and 
                         {Universidade Federal do Rio Grande do Norte (UFRN)} and 
                         {Universidade de S{\~a}o Paulo (USP)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Universidade Federal do Rio 
                         Grande do Norte (UFRN)} and {Universidade de S{\~a}o Paulo (USP)} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Federal do Rio Grande do Norte (UFRN)} and 
                         {Universidade Estadual de Feira de Santana}",
                title = "Orbital period variation of KIC 10544976: applegate mechanism 
                         versus light travel time effect",
              journal = "Astronomical Journal",
                 year = "2019",
               volume = "157",
               number = "4",
                pages = "e150",
                month = "Apr.",
             keywords = "binaries: eclipsing, planetary systems, stars: activity, stars: 
                         flare, stars: individual (KIC 10544976), starspots.",
             abstract = "In recent years, several close post-common-envelope eclipsing 
                         binaries have been found to show cyclic eclipse timing variations 
                         (ETVs). This effect is usually interpreted either as the 
                         gravitational interaction among circumbinary bodies and the host 
                         binary-known as the light travel time (LTT) effect-or as the 
                         quadrupole moment variations in one magnetic active 
                         component-known as the Applegate mechanism. In this study, we 
                         present an analysis of the ETV and the magnetic cycle of the close 
                         binary KIC 10544976. This system is composed of a white dwarf and 
                         a red dwarf in a short orbital period (0.35 days) and was 
                         monitored by ground-based telescopes between 2005 and 2017 and by 
                         the Kepler satellite between 2009 and 2013. Using the Kepler data, 
                         we derived the magnetic cycle of the red dwarf by two ways: the 
                         rate and energy of flares and the variability due to spots. Both 
                         methods resulted in a cycle of similar to 600 days, which is in 
                         agreement with magnetic cycles measured for single low-mass stars. 
                         The orbital period of KIC 10544976 shows only one long-term 
                         variation which can be fitted by an LTT effect with period of 
                         similar to 16.8 yr. Hence, one possible explanation for the ETVs 
                         is the presence of a circumbinary body with a minimal mass of 
                         similar to 13.4 M-Jup.In- the particular scenario of coplanarity 
                         between the external body and the inner binary, the third body 
                         mass is also similar to 13.4 M-Jup. In this case, the circumbinary 
                         planet must either have survived the evolution of the host binary 
                         or have been formed as a consequence of its evolution.",
                  doi = "10.3847/1538-3881/ab0963",
                  url = "http://dx.doi.org/10.3847/1538-3881/ab0963",
                 issn = "0004-6256",
             language = "en",
           targetfile = "almeida_orbital.pdf",
        urlaccessdate = "29 nov. 2020"