EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky

We measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5–M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the south, producing 2-minute cadence light curves since 2016. Long-term, high-...

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Autores: Haislip, Joshua, Howard, Ward S., Corbett, Hank, Law, Nicholas M., Ratzloff, Jeffrey K., Galliher, Nathan, Glazier, Amy, Fors Aldrich, Octavi, Ser Badia, Daniel del
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2020
País:España
Institución:Universidad de Barcelona
Repositorio:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/207422
Acceso en línea:https://hdl.handle.net/2445/207422
Access Level:acceso abierto
Palabra clave:Estels
Fotometria
Stars
Photometry
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spelling EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern SkyHaislip, JoshuaHoward, Ward S.Corbett, HankLaw, Nicholas M.Ratzloff, Jeffrey K.Galliher, NathanGlazier, AmyFors Aldrich, OctaviSer Badia, Daniel delEstelsFotometriaStarsPhotometryWe measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5–M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the south, producing 2-minute cadence light curves since 2016. Long-term, high-cadence observations of rotating flare stars probe the complex relationship between stellar rotation, starspots, and superflares. We detect periods from 0.3487 to 104 days and observe amplitudes from 0.008 to 0.216 <em>g</em>' mag. We find that the Evryscope amplitudes are larger than those in TESS with the effect correlated to stellar mass (<em>p</em>-value = 0.01). We compute the Rossby number (<em>Ro</em>) and find that our sample selected for flaring has twice as many intermediate rotators (0.04 < <em>Ro</em> < 0.4) as fast (<em>Ro</em> < 0.04) or slow (<em>Ro</em> > 0.44) rotators; this may be astrophysical or a result of period detection sensitivity. We discover 30 fast, 59 intermediate, and 33 slow rotators. We measure a median starspot coverage of 13% of the stellar hemisphere and constrain the minimum magnetic field strength consistent with our flare energies and spot coverage to be 500 G, with later-type stars exhibiting lower values than earlier-type stars. We observe a possible change in superflare rates at intermediate periods. However, we do not conclusively confirm the increased activity of intermediate rotators seen in previous studies. We split all rotators at <em>Ro</em> ∼ 0.2 into bins of <em>P</em>Rot < 10 days and <em>P</em>Rot > 10 days to confirm that short-period rotators exhibit higher superflare rates, larger flare energies, and higher starspot coverage than do long-period rotators, at <em>p</em>-values of 3.2 × 10−5, 1.0 × 10−5, and 0.01, respectively.Institute of Physics (IOP)2020info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/207422Articles publicats en revistes (Física Quàntica i Astrofísica)reponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglésReproducció del document publicat a: https://doi.org/10.3847/1538-4357/ab9081Astrophysical Journal, 2020, vol. 895, num.2, p. 1-16https://doi.org/10.3847/1538-4357/ab9081(c) American Astronomical Society, 2020info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/2074222026-05-27T06:46:51Z
dc.title.none.fl_str_mv EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
title EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
spellingShingle EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
Haislip, Joshua
Estels
Fotometria
Stars
Photometry
title_short EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
title_full EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
title_fullStr EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
title_full_unstemmed EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
title_sort EvryFlare. II. Rotation Periods of the Cool Flare Stars in TESS across Half the Southern Sky
dc.creator.none.fl_str_mv Haislip, Joshua
Howard, Ward S.
Corbett, Hank
Law, Nicholas M.
Ratzloff, Jeffrey K.
Galliher, Nathan
Glazier, Amy
Fors Aldrich, Octavi
Ser Badia, Daniel del
author Haislip, Joshua
author_facet Haislip, Joshua
Howard, Ward S.
Corbett, Hank
Law, Nicholas M.
Ratzloff, Jeffrey K.
Galliher, Nathan
Glazier, Amy
Fors Aldrich, Octavi
Ser Badia, Daniel del
author_role author
author2 Howard, Ward S.
Corbett, Hank
Law, Nicholas M.
Ratzloff, Jeffrey K.
Galliher, Nathan
Glazier, Amy
Fors Aldrich, Octavi
Ser Badia, Daniel del
author2_role author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Estels
Fotometria
Stars
Photometry
topic Estels
Fotometria
Stars
Photometry
description We measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5–M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the south, producing 2-minute cadence light curves since 2016. Long-term, high-cadence observations of rotating flare stars probe the complex relationship between stellar rotation, starspots, and superflares. We detect periods from 0.3487 to 104 days and observe amplitudes from 0.008 to 0.216 <em>g</em>' mag. We find that the Evryscope amplitudes are larger than those in TESS with the effect correlated to stellar mass (<em>p</em>-value = 0.01). We compute the Rossby number (<em>Ro</em>) and find that our sample selected for flaring has twice as many intermediate rotators (0.04 < <em>Ro</em> < 0.4) as fast (<em>Ro</em> < 0.04) or slow (<em>Ro</em> > 0.44) rotators; this may be astrophysical or a result of period detection sensitivity. We discover 30 fast, 59 intermediate, and 33 slow rotators. We measure a median starspot coverage of 13% of the stellar hemisphere and constrain the minimum magnetic field strength consistent with our flare energies and spot coverage to be 500 G, with later-type stars exhibiting lower values than earlier-type stars. We observe a possible change in superflare rates at intermediate periods. However, we do not conclusively confirm the increased activity of intermediate rotators seen in previous studies. We split all rotators at <em>Ro</em> ∼ 0.2 into bins of <em>P</em>Rot < 10 days and <em>P</em>Rot > 10 days to confirm that short-period rotators exhibit higher superflare rates, larger flare energies, and higher starspot coverage than do long-period rotators, at <em>p</em>-values of 3.2 × 10−5, 1.0 × 10−5, and 0.01, respectively.
publishDate 2020
dc.date.none.fl_str_mv 2020
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/207422
url https://hdl.handle.net/2445/207422
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: https://doi.org/10.3847/1538-4357/ab9081
Astrophysical Journal, 2020, vol. 895, num.2, p. 1-16
https://doi.org/10.3847/1538-4357/ab9081
dc.rights.none.fl_str_mv (c) American Astronomical Society, 2020
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) American Astronomical Society, 2020
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Institute of Physics (IOP)
publisher.none.fl_str_mv Institute of Physics (IOP)
dc.source.none.fl_str_mv Articles publicats en revistes (Física Quàntica i Astrofísica)
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,300719

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