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dc.contributor.authorPeacock, Sarah
dc.contributor.authorBarman, Travis
dc.contributor.authorShkolnik, Evgenya L.
dc.contributor.authorLoyd, R. O. Parke
dc.contributor.authorSchneider, Adam C.
dc.contributor.authorPagano, Isabella
dc.contributor.authorMeadows, Victoria S.
dc.date.accessioned2020-11-23T23:18:24Z
dc.date.available2020-11-23T23:18:24Z
dc.date.issued2020-05-19
dc.identifier.citationPeacock, S., Barman, T., Shkolnik, E. L., Loyd, R. P., Schneider, A. C., Pagano, I., & Meadows, V. S. (2020). HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Stars. The Astrophysical Journal, 895(1), 5.en_US
dc.identifier.issn0004-637X
dc.identifier.doi10.3847/1538-4357/ab893a
dc.identifier.urihttp://hdl.handle.net/10150/648577
dc.description.abstractQuantifying the evolution of stellar extreme ultraviolet (EUV, 100-1000 A) emission is critical for assessing the evolution of planetary atmospheres and the habitability of M dwarf systems. Previous studies from the HAbitable Zones and M dwarf Activity across Time (HAZMAT) program showed the far- and near-UV (FUV, NUV) emission from M stars at various stages of a stellar lifetime through photometric measurements from the Galaxy Evolution Explorer (GALEX). The results revealed increased levels of short-wavelength emission that remain elevated for hundreds of millions of years. The trend for EUV flux as a function of age could not be determined empirically because absorption by the interstellar medium prevents access to the EUV wavelengths for the vast majority of stars. In this paper, we model the evolution of EUV flux from early M stars to address this observational gap. We present synthetic spectra spanning EUV to infrared wavelengths of 0.4 0.05 M-& x2609; stars at five distinct ages between 10 and 5000 Myr, computed with the PHOENIX atmosphere code and guided by the GALEX photometry. We model a range of EUV fluxes spanning two orders of magnitude, consistent with the observed spread in X-ray, FUV, and NUV flux at each epoch. Our results show that the stellar EUV emission from young M stars is 100 times stronger than field age M stars, and decreases as t(-1) after remaining constant for a few hundred million years. This decline stems from changes in the chromospheric temperature structure, which steadily shifts outward with time. Our models reconstruct the full spectrally and temporally resolved history of an M star's UV radiation, including the unobservable EUV radiation, which drives planetary atmospheric escape, directly impacting a planet's potential for habitability.en_US
dc.description.sponsorshipNASA Earth and Space Science Fellowship Programen_US
dc.language.isoenen_US
dc.publisherIOP PUBLISHING LTDen_US
dc.rights© 2020. The American Astronomical Society. All rights reserved.en_US
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectStellar activityen_US
dc.subjectStellar chromospheresen_US
dc.subjectLow mass starsen_US
dc.subjectM starsen_US
dc.subjectUltraviolet astronomyen_US
dc.subjectStellar evolutionen_US
dc.titleHAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Starsen_US
dc.typeArticleen_US
dc.identifier.eissn1538-4357
dc.contributor.departmentUniv Arizona, Lunar & Planetary Laben_US
dc.identifier.journalASTROPHYSICAL JOURNALen_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.journaltitleThe Astrophysical Journal
dc.source.volume895
dc.source.issue1
dc.source.beginpage5
refterms.dateFOA2020-11-23T23:18:24Z


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