Stellar Obliquity from Spot Transit Mapping of Kepler-210

dc.contributor.authorValio A.
dc.contributor.authorAraujo A.
dc.date.accessioned2024-03-12T19:13:02Z
dc.date.available2024-03-12T19:13:02Z
dc.date.issued2022
dc.description.abstract© 2022. The Author(s). Published by the American Astronomical Society.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°, 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° implied an orbital obliquity of 18°-45° for Kepler-210 c. Further considering a symmetric spot distribution in latitude with respect to the stellar equator, the obliquity was restricted to 34.°8, implying a maximum spot latitude of 40°. 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 ΔΩ = 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.
dc.description.issuenumber2
dc.description.volume940
dc.identifier.doi10.3847/1538-4357/ac9af6
dc.identifier.issn1538-4357
dc.identifier.urihttps://dspace.mackenzie.br/handle/10899/34262
dc.relation.ispartofAstrophysical Journal
dc.rightsAcesso Aberto
dc.titleStellar Obliquity from Spot Transit Mapping of Kepler-210
dc.typeArtigo
local.scopus.citations2
local.scopus.eid2-s2.0-85143652461
local.scopus.updated2024-06-01
local.scopus.urlhttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85143652461&origin=inward
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