Hα and the Ca II H and K lines as activity proxies for late-type stars

Context. The main chromospheric activity indicator is the S index, which is the ratio of the flux in the core of the Ca II H and K lines to the continuum nearby, and is well studied for stars from F to K. Another chromospheric proxy is the Ha line, which is believed to be tightly correlated with the...

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Autores principales: Cincunegui, C., Díaz, R.F., Mauas, P.J.D.
Formato: JOUR
Materias:
Stars: activity
Stars: chromospheres
Stars: late-type
Activity proxies
Spectral range
Stellar color
Calcium
Chromosomes
Continuum mechanics
Correlation methods
Hydrogen
Magnetic flux
Spacecraft observatories
Stars
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00046361_v469_n1_p309_Cincunegui
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00046361_v469_n1_p309_Cincunegui
record_format dspace
spelling todo:paper_00046361_v469_n1_p309_Cincunegui2023-10-03T14:00:19Z Hα and the Ca II H and K lines as activity proxies for late-type stars Cincunegui, C. Díaz, R.F. Mauas, P.J.D. Stars: activity Stars: chromospheres Stars: late-type Activity proxies Spectral range Stellar color Calcium Chromosomes Continuum mechanics Correlation methods Hydrogen Magnetic flux Spacecraft observatories Stars Context. The main chromospheric activity indicator is the S index, which is the ratio of the flux in the core of the Ca II H and K lines to the continuum nearby, and is well studied for stars from F to K. Another chromospheric proxy is the Ha line, which is believed to be tightly correlated with the Ca II index. Aims. In this work we characterize both chromospheric activity indicators, the one associated with the H and K Ca II lines and the other with Ha, for the whole range of late type stars, from F to M. Methods. We present periodic medium-resolution echelle observations covering the complete visual range, taken at the CASLEO Argentinean Observatory over 7 years. We use a total of 917 flux-calibrated spectra for 109 stars that range from F6 to M5. We statistically study these two indicators for stars of different activity levels and spectral types. Results. We directly derive the conversion factor that translates the known S index to flux in the Ca II cores, and extend its calibration to a wider spectral range. We investigate the relation between the activity measurements in the calcium and hydrogen lines, and found that the usual correlation observed is the product of the dependence of each flux on stellar colour, and not the product of similar activity phenomena. © ESO 2007. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00046361_v469_n1_p309_Cincunegui
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: late-type
Activity proxies
Spectral range
Stellar color
Calcium
Chromosomes
Continuum mechanics
Correlation methods
Hydrogen
Magnetic flux
Spacecraft observatories
Stars
spellingShingle Stars: activity
Stars: chromospheres
Stars: late-type
Activity proxies
Spectral range
Stellar color
Calcium
Chromosomes
Continuum mechanics
Correlation methods
Hydrogen
Magnetic flux
Spacecraft observatories
Stars
Cincunegui, C.
Díaz, R.F.
Mauas, P.J.D.
Hα and the Ca II H and K lines as activity proxies for late-type stars
topic_facet Stars: activity
Stars: chromospheres
Stars: late-type
Activity proxies
Spectral range
Stellar color
Calcium
Chromosomes
Continuum mechanics
Correlation methods
Hydrogen
Magnetic flux
Spacecraft observatories
Stars
description Context. The main chromospheric activity indicator is the S index, which is the ratio of the flux in the core of the Ca II H and K lines to the continuum nearby, and is well studied for stars from F to K. Another chromospheric proxy is the Ha line, which is believed to be tightly correlated with the Ca II index. Aims. In this work we characterize both chromospheric activity indicators, the one associated with the H and K Ca II lines and the other with Ha, for the whole range of late type stars, from F to M. Methods. We present periodic medium-resolution echelle observations covering the complete visual range, taken at the CASLEO Argentinean Observatory over 7 years. We use a total of 917 flux-calibrated spectra for 109 stars that range from F6 to M5. We statistically study these two indicators for stars of different activity levels and spectral types. Results. We directly derive the conversion factor that translates the known S index to flux in the Ca II cores, and extend its calibration to a wider spectral range. We investigate the relation between the activity measurements in the calcium and hydrogen lines, and found that the usual correlation observed is the product of the dependence of each flux on stellar colour, and not the product of similar activity phenomena. © ESO 2007.
format JOUR
author Cincunegui, C.
Díaz, R.F.
Mauas, P.J.D.
author_facet Cincunegui, C.
Díaz, R.F.
Mauas, P.J.D.
author_sort Cincunegui, C.
title Hα and the Ca II H and K lines as activity proxies for late-type stars
title_short Hα and the Ca II H and K lines as activity proxies for late-type stars
title_full Hα and the Ca II H and K lines as activity proxies for late-type stars
title_fullStr Hα and the Ca II H and K lines as activity proxies for late-type stars
title_full_unstemmed Hα and the Ca II H and K lines as activity proxies for late-type stars
title_sort hα and the ca ii h and k lines as activity proxies for late-type stars
url http://hdl.handle.net/20.500.12110/paper_00046361_v469_n1_p309_Cincunegui
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