FLORES TRIVIGNO Matias Gaston
congresos y reuniones científicas
Searching for activity variations by using the Hα line
MATÍAS FLORES; FEDERICO GONZÁLEZ; MARCELO JAQUE ARANCIBIA; CARLOS SAFFE; PAULA MIQUELARENA
Workshop; Primer Workshop Internacional CART (Chinese Argentine Radio-Telescope); 2019
Currently, the monitoring of many stars showing magnetic cycles could help for better understanding their dependence with the stellar properties and the place occupied by the Sun in this context. Up to now, thereare many questions related to the solar case which have not yet been resolved. For instance: why the amplitude of successive solar cycles is not constant, including their overall shape which frequently differs from one cycle to another. In addition, the solar cycle duration is not uniform (Charbonneau 2010, Hathaway 2010). Also, the study of how these types of stars could vary is relevant for understanding long-term solar luminosity variations during cycling periods as well as non-cycling periods such as the Maunder Minimum of 1645?1715 (Hall et al., 2007, 2009). In this line, is the Maunder Minimum a typical and frequent event? What was the cause of this phenomenon? Most stellar activity cycles similar to that found in the Sun have been detected by using the chromosphericCa II H&K lines as stellar activity proxies, through the Mount Wilson index (SMW). However, it is unclear ifsuch activity cycles could be identified using other optical lines. Although several studies have suggested that the correlation between the chromospheric emission from the Ca II H&K and Hα lines present in Suncould be found in other stars (e.g. Meunier & Delfosse 2009, Martínez-Arnáiz et al. 2010, 2011, Stelzer et al. 2013), this correlation has been reported as not always valid (Cincunegui et al. 2007, Gomes da Silva etal. 2014). Our main goal is to search for variations in Ca II H&K and Hα lines in a sample of FGK stars. In this way, we can perform a detailed long-term activity study of these stars and also search for new activity proxies, asseems to be the case of the shape variation of Hα line (Flores et al. 2018).