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  Chromospheric activity catalogue of 4454 cool stars: Questioning the active branch of stellar activity cycles

Boro Saikia, S., Marvin, C. J., Jeffers, S. V., Reiners, A., Cameron, R. H., Marsden, S. C., et al. (2018). Chromospheric activity catalogue of 4454 cool stars: Questioning the active branch of stellar activity cycles. Astronomy and Astrophysics, 616: A108. doi:10.1051/0004-6361/201629518.

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Boro Saikia, S. , Author
Marvin, C. J., Author
Jeffers, S. V., Author
Reiners, A., Author
Cameron, Robert H.1, 2, Author              
Marsden, S. C., Author
Petit, P., Author
Warnecke, Jörn1, 2, Author              
Yadav, A. P., Author
1Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832287              
2Max Planck Research Group in Solar and Stellar Magnetic Activity (Mag Activity) – SOLSTAR, Max Planck Institute for Solar System Research, Max Planck Society, Justus-von-Liebig-Weg 3, 37077 Göttingen, DE, ou_2265638              


Free keywords: stars: chromospheres / stars: activity / stars: solar-type / stars: late-type
 Abstract: Context. Chromospheric activity monitoring of a wide range of cool stars can provide valuable information on stellar magnetic activity and its dependence on fundamental stellar parameters such as effective temperature and rotation. Aims. We compile a chromospheric activity catalogue of 4454 cool stars from a combination of archival HARPS spectra and multiple other surveys, including the Mount Wilson data that have recently been released by the NSO. We explore the variation in chromospheric activity of cool stars along the main sequence for stars with different effective temperatures. Additionally, we also perform an activity-cycle period search and investigate its relation with rotation. Methods. The chromospheric activity index, S-index, was measured for 304 main-sequence stars from archived high-resolution HARPS spectra. Additionally, the measured and archived S-indices were converted into the chromospheric flux ratio log RHK'. The activity-cycle periods were determined using the generalised Lomb-Scargle periodogram to study the active and inactive branches on the rotation – activity-cycle period plane. Results. The global sample shows that the bimodality of chromospheric activity, known as the Vaughan-Preston gap, is not prominent, with a significant percentage of the stars at an intermediate-activity level around R'HK = −4.75. Independently, the cycle period search shows that stars can lie in the region intermediate between the active and inactive branch, which means that the active branch is not as clearly distinct as previously thought. Conclusions. The weakening of the Vaughan-Preston gap indicates that cool stars spin down from a higher activity level and settle at a lower activity level without a sudden break at intermediate activity. Some cycle periods are close to the solar value between the active and inactive branch, which suggests that the solar dynamo is most likely a common case of the stellar dynamo.


Language(s): eng - English
 Dates: 2018
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1051/0004-6361/201629518
 Degree: -



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Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
Publ. Info: Les Ulis Cedex A France : EDP Sciences
Pages: - Volume / Issue: 616 Sequence Number: A108 Start / End Page: - Identifier: Other: 1432-0746
ISSN: 0004-6361
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1