A possible long-term activity cycle for ι Horologii: First results from SPI-HKα project

FLORES, M.; BUCCINO, A.P.; SAFFE, C; MAUAS, P.J.D.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 464 p. 4299 - 4305

0035-8711

To detect stellar activity cycles and study the possible star-planetinteractions (SPI´s), we have developed both HKα and SPI-HKαprojects since 1999 and 2012 respectively.In this work, we present preliminary results of possible SPI´s studying thechromospheric activity and look for possible correlations between stellaractivity and stellar/planetary parameters. We find that for stars with similarTeff, stellar activity increases with the mass of the planet, similar toprevious works. However, stellar ages can also play a role and a larger stellarsample is needed to verify these trends. We also note that some of these starspresent a remarkably high level of chromospheric activity, even comparable withRSCvn or BY Dra active stars. In addition, we do not observe any correlationbetween stellar activity and semi-major axis.We present the first long-term activity study of the star ι Horologii,a young solar-type star which hosts a non-transiting Jovian planet and presentsa high activity level. We analyze our own spectra, obtained between 2002 and2015, combined with public HARPS observations. We calculate the Ca II indexesderived from the 987 CASLEO and HARPS spectra and convert them to theMount-Wilson scale. We found a long-term activity cycle of ∼ 5 years whichfits the active sequence of Bohm-Vitense. The amplitude of this longer cycle isirregular, as was also observed for the shorter one. This fact could beattributed to an antisymmetric distribution of active regions on the stellarsurface.