Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates

Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca II H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims. We aim to detect activity cycle...

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Autores principales:	Flores, M., González, J.F., Jaque Arancibia, M., Buccino, A., Saffe, C.
Formato:	JOUR
Materias:	stars: activity stars: chromospheres stars: individual: HD 45184 stars: solar-type Astrophysics Calcium Chromophores Chromospheric activity Lomb-scargle periodogram Spectral variation Stars: activity Stars: chromospheres Stars: individual Stars: solar types Temporal coverage Stars
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_00046361_v589_n_p_Flores
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

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spelling	todo:paper_00046361_v589_n_p_Flores2023-10-03T14:00:57Z Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates Flores, M. González, J.F. Jaque Arancibia, M. Buccino, A. Saffe, C. stars: activity stars: chromospheres stars: individual: HD 45184 stars: solar-type Astrophysics Calcium Chromophores Chromospheric activity Lomb-scargle periodogram Spectral variation Stars: activity Stars: chromospheres Stars: individual Stars: solar types Temporal coverage Stars Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca II H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims. We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long- and short-term activity variations. Methods. We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca II H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca II H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe II and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results. We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe II lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba II and Ti II lines present variations at 3σ level, which could be considered as marginal variations. From short-term modulation of the S index we calculate a rotational period of 19.98 days, which agrees with its mean chromospheric activity level. We also clearly show that the activity cycles of HD 45184 can be detected in both Fe II and Balmer lines. © ESO, 2016. Fil:Buccino, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00046361_v589_n_p_Flores
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	stars: activity stars: chromospheres stars: individual: HD 45184 stars: solar-type Astrophysics Calcium Chromophores Chromospheric activity Lomb-scargle periodogram Spectral variation Stars: activity Stars: chromospheres Stars: individual Stars: solar types Temporal coverage Stars
spellingShingle	stars: activity stars: chromospheres stars: individual: HD 45184 stars: solar-type Astrophysics Calcium Chromophores Chromospheric activity Lomb-scargle periodogram Spectral variation Stars: activity Stars: chromospheres Stars: individual Stars: solar types Temporal coverage Stars Flores, M. González, J.F. Jaque Arancibia, M. Buccino, A. Saffe, C. Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
topic_facet	stars: activity stars: chromospheres stars: individual: HD 45184 stars: solar-type Astrophysics Calcium Chromophores Chromospheric activity Lomb-scargle periodogram Spectral variation Stars: activity Stars: chromospheres Stars: individual Stars: solar types Temporal coverage Stars
description	Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca II H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims. We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long- and short-term activity variations. Methods. We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca II H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca II H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe II and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results. We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe II lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba II and Ti II lines present variations at 3σ level, which could be considered as marginal variations. From short-term modulation of the S index we calculate a rotational period of 19.98 days, which agrees with its mean chromospheric activity level. We also clearly show that the activity cycles of HD 45184 can be detected in both Fe II and Balmer lines. © ESO, 2016.
format	JOUR
author	Flores, M. González, J.F. Jaque Arancibia, M. Buccino, A. Saffe, C.
author_facet	Flores, M. González, J.F. Jaque Arancibia, M. Buccino, A. Saffe, C.
author_sort	Flores, M.
title	Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
title_short	Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
title_full	Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
title_fullStr	Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
title_full_unstemmed	Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates
title_sort	discovery of an activity cycle in the solar analog hd 45184 exploring balmer and metallic lines as activity proxy candidates
url	http://hdl.handle.net/20.500.12110/paper_00046361_v589_n_p_Flores
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Discovery of an activity cycle in the solar analog HD 45184 Exploring Balmer and metallic lines as activity proxy candidates

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