| Texto completo | |
| Autor(es): |
Valio, Adriana
;
Araujo, Alexandre
Número total de Autores: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | ASTROPHYSICAL JOURNAL; v. 940, n. 2, p. 10-pg., 2022-12-01. |
| Resumo | |
Stellar obliquity, the angle between the stellar spin and the perpendicular to the planetary orbit, also known as the spin-orbit angle, holds clues to the formation and evolution of planetary systems. When a planet transits a star periodically, it may cross in front of a stellar spot, producing a noticeable signal on the transit light curve. Spot transit mapping can be used to measure stellar obliquity. Here we present the analysis of Kepler-210, a K-dwarf star with two mini-Neptune-size planets in orbit. Interestingly, the spot mapping from the outer planet, Kepler-210 c, resulted in a spot distribution with no spots detected at longitudes >38 degrees, whereas the spots occulted by Kepler-210 b displayed all range of longitudes. The best explanation for this was that Kepler-210 c exhibited an inclined orbit, while the orbit of Kepler-210 b was parallel to the stellar equator. Thus, transits of Kepler-210 c occulted different latitude bands of the star. The observed maximum spot topocentric longitude of 38 degrees implied an orbital obliquity of 18 degrees-45 degrees for Kepler-210 c. Further considering a symmetric spot distribution in latitude with respect to the stellar equator, the obliquity was restricted to 34.degrees 8, implying a maximum spot latitude of 40 degrees. The differential rotation profile calculated from the oblique orbit for Kepler-210 c agreed with that obtained from the spots occulted by Kepler-210 b. Combining results from both planets yields a rotational shear of Delta omega = 0.0353 +/- 0.0002 rad day(-1) and a relative rotational shear of 6.9%. The causes of the Kepler-210 c misalignment remain to be explained. (AU) | |
| Processo FAPESP: | 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA) |
| Beneficiário: | Elisabete Maria de Gouveia Dal Pino |
| Modalidade de apoio: | Auxílio à Pesquisa - Projetos Especiais |