Ross 128 - GL 447: A possible activity cycle for a slow-rotating fully-convective star

ROMINA IBAÑEZ BUSTOS; ANDREA BUCCINO; FLORES, M.; PABLO MAUAS

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2019 vol. 628

0004-6361

Context. Long-term chromospheric activity in slow-rotating fully- convective stars has been scarcely explored. Ross 128 (Gl 447) is aslow-rotator and inactive dM4 star which has been extensively observed. It hosts the fourth closest extrasolar planet.Aims. Ross 128 is an ideal target to test dynamo theories in slow-rotating low-mass star.Methods. To characterize the magnetic activity of Ross 128 we study the Sk-indexes derived from CASLEO, HARPS, FEROS, UVES and XSHOOTER spectra. Using the Generalized Lomb-Scargle and CLEAN periodograms, we analyze the whole Sk time-series obtained between 2004 and 2018. We perform a similar analysis for the Na I index and we analyze its relation with the Sk-index.Results. From both indexes, we obtain a possible activity cycle with a ∼5-year period, which is one of a small handful of activity cycles reported for a slow-rotating fully convective star.