Volume 628, August 2019
|Number of page(s)||6|
|Section||Letters to the Editor|
|Published online||29 July 2019|
Letter to the Editor
Ross 128 – GL 447
A possible activity cycle for a slow-rotating fully convective star
Instituto de Astronomía y Física del Espacio (CONICET-UBA), C.C. 67 Sucursal 28, C1428EHA Buenos Aires, Argentina
2 Departamento de Física. FI, Universidad de Buenos Aires, Buenos Aires, Argentina
3 Departamento de Física. FCEyN, Universidad de Buenos Aires, Buenos Aires, Argentina
4 Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE-CONICET), San Juan, Argentina
5 Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, San Juan, Argentina
Accepted: 6 July 2019
Context. Long-term chromospheric activity in slow-rotating fully convective stars has scarcely been explored. Ross 128 (Gl 447) is a slow-rotator and inactive dM4 star that 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 stars.
Methods. To characterize the magnetic activity of Ross 128, we studied the SK-indexes derived from CASLEO, HARPS, FEROS, UVES, and X-shooter spectra. Using the generalized Lomb-Scargle and CLEAN periodograms, we analyzed the whole SK time-series obtained between 2004 and 2018. We performed a similar analysis for the Na I-index, and we analyzed its relation with the SK-index.
Results. From both indexes, we obtain a possible activity cycle with a period of about five years, which is one of a small handful of activity cycles that have been reported for a slow-rotating fully convective star.
Key words: stars: activity / stars: late-type / techniques: spectroscopic
© ESO 2019
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