Issue |
A&A
Volume 628, August 2019
|
|
---|---|---|
Article Number | L1 | |
Number of page(s) | 6 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/201936030 | |
Published online | 29 July 2019 |
Letter to the Editor
Ross 128 – GL 447
A possible activity cycle for a slow-rotating fully convective star
1
Instituto de Astronomía y Física del Espacio (CONICET-UBA), C.C. 67 Sucursal 28, C1428EHA Buenos Aires, Argentina
e-mail: ribanez@iafe.uba.ar
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
Received:
5
June
2019
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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