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Article: Discovery of remarkably intense radio emission from a young and rapidly rotating dMe star

TitleDiscovery of remarkably intense radio emission from a young and rapidly rotating dMe star
Authors
KeywordsRadio Continuum: Stars
Stars: Activity
Stars: Coronae
Stars: Late-Type
Stars: Magnetic Fields
Issue Date1993
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205
Citation
Astrophysical Journal Letters, 1993, v. 405 n. 1 PART 2, p. L33-L37 How to Cite?
AbstractI report the serendipitous discovery of remarkably intense radio emission from the dM4e star Rositter 137B. This star is rotating very rapidly (P rot ≤ 9 hr) and is believed to have an age of ∼5-8 × 10 7 yr and therefore still contracting onto the main sequence. The remarkably intense radio emission of Rst 137B suggests that (some) older solar-neighborhood dMe flare stars, which are believed to be near or at the zero-age main sequence (ZAMS; age of 10 8-10 9 yr), may have evolved through a stage of even higher radio activity than their presently already elevated levels. This in turn may indicate that the magnetic dynamo of M dwarf stars decays in strength well before these stars reach the ZAMS; on the other hand, if as is suggested by Linsky & Saar the magnetic dynamo of many near-ZAMS solar-neighborhood dMe flare stars are still operating in a regime of saturation, then younger and/or more rapidly rotating M dwarf stars may be able to more efficiently convert magnetic energy to radio energy. Rst 137B appears to display quite steady quiescent emission. On one occasion its quiescent emission was observed to be circularly polarized in the opposite sense to that of coherent flares, providing perhaps the first unambiguous evidence that the quiescent emission of dMe flare stars can attain quite high degrees of circular polarization. If, as current evidence suggests, both the quiescent and flaring emission of flare stars originate predominantly from magnetic fields with the same polarity, this observation also could provide the first tentative identification of the magnetoionic mode of coherent stellar microwave flares. The two coherent flares observed on Rst 137B were inferred to be polarized in the sense of the o-mode, not the x-mode as predicted by the popular interpretation of electron-cyclotron maser theory. This theory, however, does predict that under stellar conditions less favorable for the growth of electromagnetic maser waves than has generally been assumed, o-mode can dominate over x-mode emission.
Persistent Identifierhttp://hdl.handle.net/10722/174920
ISSN
2015 Impact Factor: 5.487
2015 SCImago Journal Rankings: 3.369

 

DC FieldValueLanguage
dc.contributor.authorLim, Jen_US
dc.date.accessioned2012-11-26T08:48:07Z-
dc.date.available2012-11-26T08:48:07Z-
dc.date.issued1993en_US
dc.identifier.citationAstrophysical Journal Letters, 1993, v. 405 n. 1 PART 2, p. L33-L37en_US
dc.identifier.issn2041-8205en_US
dc.identifier.urihttp://hdl.handle.net/10722/174920-
dc.description.abstractI report the serendipitous discovery of remarkably intense radio emission from the dM4e star Rositter 137B. This star is rotating very rapidly (P rot ≤ 9 hr) and is believed to have an age of ∼5-8 × 10 7 yr and therefore still contracting onto the main sequence. The remarkably intense radio emission of Rst 137B suggests that (some) older solar-neighborhood dMe flare stars, which are believed to be near or at the zero-age main sequence (ZAMS; age of 10 8-10 9 yr), may have evolved through a stage of even higher radio activity than their presently already elevated levels. This in turn may indicate that the magnetic dynamo of M dwarf stars decays in strength well before these stars reach the ZAMS; on the other hand, if as is suggested by Linsky & Saar the magnetic dynamo of many near-ZAMS solar-neighborhood dMe flare stars are still operating in a regime of saturation, then younger and/or more rapidly rotating M dwarf stars may be able to more efficiently convert magnetic energy to radio energy. Rst 137B appears to display quite steady quiescent emission. On one occasion its quiescent emission was observed to be circularly polarized in the opposite sense to that of coherent flares, providing perhaps the first unambiguous evidence that the quiescent emission of dMe flare stars can attain quite high degrees of circular polarization. If, as current evidence suggests, both the quiescent and flaring emission of flare stars originate predominantly from magnetic fields with the same polarity, this observation also could provide the first tentative identification of the magnetoionic mode of coherent stellar microwave flares. The two coherent flares observed on Rst 137B were inferred to be polarized in the sense of the o-mode, not the x-mode as predicted by the popular interpretation of electron-cyclotron maser theory. This theory, however, does predict that under stellar conditions less favorable for the growth of electromagnetic maser waves than has generally been assumed, o-mode can dominate over x-mode emission.en_US
dc.languageengen_US
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/2041-8205en_US
dc.relation.ispartofAstrophysical Journal Lettersen_US
dc.subjectRadio Continuum: Starsen_US
dc.subjectStars: Activityen_US
dc.subjectStars: Coronaeen_US
dc.subjectStars: Late-Typeen_US
dc.subjectStars: Magnetic Fieldsen_US
dc.titleDiscovery of remarkably intense radio emission from a young and rapidly rotating dMe staren_US
dc.typeArticleen_US
dc.identifier.emailLim, J: jjlim@hku.hken_US
dc.identifier.authorityLim, J=rp00745en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-12044259804en_US
dc.identifier.volume405en_US
dc.identifier.issue1 PART 2en_US
dc.identifier.spageL33en_US
dc.identifier.epageL37en_US
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridLim, J=7403453870en_US

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