Do A-type stars flare?

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Pedersen, M. G. Antoci, V. Korhonen, H. White, T. R. Jessen-Hansen, J. Lehtinen, J. Nikbakhsh, S. Viuho, J. 2019-02-25T08:50:55Z 2019-02-25T08:50:55Z 2017-04
dc.identifier.citation Pedersen , M G , Antoci , V , Korhonen , H , White , T R , Jessen-Hansen , J , Lehtinen , J , Nikbakhsh , S & Viuho , J 2017 , ' Do A-type stars flare? ' Monthly Notices of the Royal Astronomical Society , vol. 466 , no. 3 , pp. 3060-3076 . en
dc.identifier.issn 0035-8711
dc.identifier.issn 1365-2966
dc.identifier.other PURE UUID: 9fc68eec-e9ec-4d03-a52f-a8d3683ca96c
dc.identifier.other PURE ITEMURL:
dc.identifier.other PURE LINK:
dc.identifier.other PURE FILEURL:
dc.description | openaire: EC/FP7/267864/EU//ASTERISK | openaire: EC/H2020/670519/EU//MAMSIE
dc.description.abstract For flares to be generated, stars have to have a sufficiently deep outer convection zone (F5 and later), strong large-scale magnetic fields (Ap/Bp-type stars) or strong, radiatively driven winds (B5 and earlier). Normal A-type stars possess none of these and therefore should not flare. Nevertheless, flares have previously been detected in the Kepler light curves of 33 A-type stars and interpreted to be intrinsic to the stars. Here, we present new and detailed analyses of these 33 stars, imposing very strict criteria for the flare detection. We confirm the presence of flare-like features in 27 of the 33 A-type stars. A study of the pixel data and the surrounding field of view reveals that 14 of these 27 flaring objects have overlapping neighbouring stars and five stars show clear contamination in the pixel data. We have obtained high-resolution spectra for 2/3 of the entire sample and confirm that our targets are indeed A-type stars. Detailed analyses revealed that 11 out of 19 stars with multiple epochs of observations are spectroscopic binaries. Furthermore, and contrary to previous studies, we find that the flares can originate from a cooler, unresolved companion. We note the presence of Hα emission in eight stars. Whether this emission is circumstellar or magnetic in origin is unknown. In summary, we find possible alternative explanations for the observed flares for at least 19 of the 33 A-type stars, but find no truly convincing target to support the hypothesis of flaring A-type stars. en
dc.format.extent 3060-3076
dc.format.mimetype application/pdf
dc.language.iso en en
dc.relation info:eu-repo/grantAgreement/EC/H2020/670519/EU//MAMSIE
dc.relation.ispartofseries Monthly Notices of the Royal Astronomical Society en
dc.relation.ispartofseries Volume 466, issue 3 en
dc.rights openAccess en
dc.subject.other 115 Astronomy and space science en
dc.title Do A-type stars flare? en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department KU Leuven
dc.contributor.department Aarhus University
dc.contributor.department University of Copenhagen
dc.contributor.department Max Planck Institute for Solar System Research
dc.contributor.department Department of Electronics and Nanoengineering
dc.contributor.department University of Helsinki
dc.contributor.department Department of Electronics and Nanoengineering en
dc.subject.keyword stars: activity
dc.subject.keyword binaries: spectroscopic
dc.subject.keyword circumstellar matter
dc.subject.keyword stars: flare
dc.subject.keyword stars: magnetic field
dc.subject.keyword 115 Astronomy and space science
dc.identifier.urn URN:NBN:fi:aalto-201902252000
dc.identifier.doi 10.1093/mnras/stw3226
dc.type.version publishedVersion

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