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《New Astronomy》2022
Detailed photometric analysis of V523 And and V543 And from the Wide Angle Search for Planets survey is presented for the first time. It was found that while V523 And is a detached binary, V543 And is a semi-detached binary star system. The adopted masses and radii for the primary and secondary components are M, R and M, R for V523 And; and M, R and M, R for V543 And. Orbital period variations of the systems were analyzed using the O-C method. The O-C change of V523 And is discussed in terms of the magnetic activity cycle of one or both components and light travel time effect (LTTE) due to a third body in the system. Among these mechanisms, LTTE seems to be the most appropriate mechanism to explain the O-C variation of the system since the quadrupole moments of the primary and secondary components () were found to be in the order of g cm. The O-C diagram of V543 And shows a downward parabolic trend, which suggests a secular period decrease with a rate of s/year. The parabolic O-C variation of V543 And was interpreted in terms of the non-conservative mass transfer mechanism. According to this scenario, the range of possible values of the mass gain rate () of the primary component of V543 And as well as the mass-loss rate () of the system were found to be – M/year and – M/year, respectively. 相似文献
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《Chinese Astronomy and Astrophysics》2023,47(2):353-375
The detection of exoplanets in the past three decades has revealed the fact that planets are ubiquitous in the universe. In order to deeply study the ubiquity of habitable planets, on one hand, we need to understand the characteristics of habitable planets; on the other hand, we can analyze the the distribution characteristics of exoplanets have been found, and to calculate the probability of occurrence of such planets around stars. Among the exoplanets that have been found so far, most of them are discovered by the transit method. For example, the number of the planets detected by the Kepler space telescope is 2344. Kepler telescope officially retired in 2018, and the Kepler team released the final version of Kepler Data Release (DR25), including a total of 198709 stars observed quarterly Q1–Q17. Here we analyze the Kepler data by using two different methods, Inverse Detection Efficiency Method (IDEM) and Maximum Likelihood Analysis (ML), to estimate planet occurrence rates in the space of the parameters of radius and orbital period. At the same time, the samples were classified according to the spectral types of stars, and the planet occurrence rates around F, G, and K Kepler stars as well as its overall formation rate were estimated respectively. We estimate the planetary occurrence rates for planets among radius range of 1–20 ( is one radius of the Earth) and orbital period range of 0.4–400 days by IDEM and ML, for which around F stars are respectively and . The rates around G stars by IDEM and ML are respectively and . The rates around K stars by IDEM and ML are respectively and . And the overall occurrence rate of such planets around F, G, K stars by IDEM and ML are respectively and . According to our estimation, we further show the results for the planet occurrence rates around stars with different spectral types by different methods, and discuss the reliability of the results in comparison with the previous studies. 相似文献
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《New Astronomy》2017
We considered one of the proton halo nuclei candidates, 13N* nucleus, and calculated the cross section and astrophysical S-factor for 12C(p, γ)13N* reaction using halo effective field theory without pion (hEFT). The halo effective field theory is used to examine the halo nucleus bound state with a large S-wave scattering length. We calculated the radiative proton capture cross section and the astrophysical S-factor from the fields of the core and the valence proton at the Leading-Order (LO). We showed that there is a good agreement among the our results for cross section and astrophysical S-factor of the 12C(p, γ)13N* reaction and the experimental data. The astrophysical S-factor that has been estimated at the zero energy (Ecm=0) by using a theoretical calculation of the cross section for direct radiative capture and an extrapolation of this calculation obtained MeV-b. 相似文献
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