HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines

Context. The detection of chromospheric activity cycles in solar-Analogue and twin stars can be used to place the solar cycle in a wider context. However, relatively few of these stars with activity cycles have been detected. It is well known that the cores of the Ca II H&K lines are modulat...

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Publicado:	2018
Materias:	Stars: Activity Stars: chromospheres Stars: individual: HD 38858 Stars: solar-Type Astrophysics Chromophores Earth (planet) Iron compounds Solar energy Chromospheric activity Detecting activities Lomb-scargle periodogram Stars: activity Stars: individual Stars: solar types Statistical moments Stars
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v620_n_p_Flores http://hdl.handle.net/20.500.12110/paper_00046361_v620_n_p_Flores
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00046361_v620_n_p_Flores
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spelling	paper:paper_00046361_v620_n_p_Flores2023-06-08T14:28:27Z HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines Stars: Activity Stars: chromospheres Stars: individual: HD 38858 Stars: solar-Type Astrophysics Chromophores Earth (planet) Iron compounds Solar energy Chromospheric activity Detecting activities Lomb-scargle periodogram Stars: activity Stars: chromospheres Stars: individual Stars: solar types Statistical moments Stars Context. The detection of chromospheric activity cycles in solar-Analogue and twin stars can be used to place the solar cycle in a wider context. However, relatively few of these stars with activity cycles have been detected. It is well known that the cores of the Ca II H&K lines are modulated by stellar activity. The behaviour of the Balmer and other optical lines with stellar activity is not yet completely understood. Aims. We search for variations in the Ca II H&K, Balmer, and Fe II lines modulated by stellar activity. In particular, we apply a novel strategy to detect possible shape variations in the Hα line. Methods. We analysed activity signatures in HD 38858 using HARPS and CASLEO spectra obtained between 2003 and 2017. We calculated the Mount Wilson index (SMW), log(R′HK), and the statistical moments of the Ca II H&K, Balmer, and other optical lines. We searched for periodicities using the generalized Lomb-Scargle periodogram. Results. We detect a long-Term activity cycle of 10.8 yr in Ca II H&K and Hα in the solar-Analogue star HD 38858. In contrast, this cycle is marginally detected in the Fe II lines. We also detect a noticeable variation in radial velocity that seems to be produced by stellar activity. Conclusions. HD 38858 is the second solar-Analogue star where we find a clear activity cycle that is replicated in the Balmer lines. Spectral indexes based on the shape of Hα line seem to be more reliable than the fluxes in the same line for detecting activity variations. The cyclic modulation we detected gives place to a variation in radial velocity that previously has been associated with a super-Earth planet. Finally, due to the similarity of HD 38858 with the Sun, we recommend to continue monitoring this star. © ESO 2018. 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v620_n_p_Flores http://hdl.handle.net/20.500.12110/paper_00046361_v620_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 38858 Stars: solar-Type Astrophysics Chromophores Earth (planet) Iron compounds Solar energy Chromospheric activity Detecting activities Lomb-scargle periodogram Stars: activity Stars: chromospheres Stars: individual Stars: solar types Statistical moments Stars
spellingShingle	Stars: Activity Stars: chromospheres Stars: individual: HD 38858 Stars: solar-Type Astrophysics Chromophores Earth (planet) Iron compounds Solar energy Chromospheric activity Detecting activities Lomb-scargle periodogram Stars: activity Stars: chromospheres Stars: individual Stars: solar types Statistical moments Stars HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
topic_facet	Stars: Activity Stars: chromospheres Stars: individual: HD 38858 Stars: solar-Type Astrophysics Chromophores Earth (planet) Iron compounds Solar energy Chromospheric activity Detecting activities Lomb-scargle periodogram Stars: activity Stars: chromospheres Stars: individual Stars: solar types Statistical moments Stars
description	Context. The detection of chromospheric activity cycles in solar-Analogue and twin stars can be used to place the solar cycle in a wider context. However, relatively few of these stars with activity cycles have been detected. It is well known that the cores of the Ca II H&K lines are modulated by stellar activity. The behaviour of the Balmer and other optical lines with stellar activity is not yet completely understood. Aims. We search for variations in the Ca II H&K, Balmer, and Fe II lines modulated by stellar activity. In particular, we apply a novel strategy to detect possible shape variations in the Hα line. Methods. We analysed activity signatures in HD 38858 using HARPS and CASLEO spectra obtained between 2003 and 2017. We calculated the Mount Wilson index (SMW), log(R′HK), and the statistical moments of the Ca II H&K, Balmer, and other optical lines. We searched for periodicities using the generalized Lomb-Scargle periodogram. Results. We detect a long-Term activity cycle of 10.8 yr in Ca II H&K and Hα in the solar-Analogue star HD 38858. In contrast, this cycle is marginally detected in the Fe II lines. We also detect a noticeable variation in radial velocity that seems to be produced by stellar activity. Conclusions. HD 38858 is the second solar-Analogue star where we find a clear activity cycle that is replicated in the Balmer lines. Spectral indexes based on the shape of Hα line seem to be more reliable than the fluxes in the same line for detecting activity variations. The cyclic modulation we detected gives place to a variation in radial velocity that previously has been associated with a super-Earth planet. Finally, due to the similarity of HD 38858 with the Sun, we recommend to continue monitoring this star. © ESO 2018.
title	HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
title_short	HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
title_full	HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
title_fullStr	HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
title_full_unstemmed	HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines
title_sort	hd 38858: a solar-type star with an activity cycle of ∼10.8 yr: searching for variations in the balmer and metallic lines
publishDate	2018
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00046361_v620_n_p_Flores http://hdl.handle.net/20.500.12110/paper_00046361_v620_n_p_Flores
_version_	1768542343128940544

HD 38858: A solar-Type star with an activity cycle of ∼10.8 yr: Searching for variations in the Balmer and metallic lines

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