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dc.date.accessioned2018-02-16T13:16:49Z
dc.date.available2018-02-16T13:16:49Z
dc.date.created2018-01-03T21:32:32Z
dc.date.issued2017
dc.identifier.citationDe Pontieu, Bart Walter Martinez-Sykora, Juan Chintzoglou, Georgios . What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?. Astrophysical Journal Letters. 2017, 849(1)
dc.identifier.urihttp://hdl.handle.net/10852/60178
dc.description.abstractSpicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100–300 km s−1 in spicules, as measured in the plane of the sky. However, line of sight measurements of such high speeds have been difficult to obtain, with values deduced from Doppler shifts in spectral lines typically of order 30–70 km s−1. In this work, we resolve this long-standing discrepancy using recent 2.5D radiative MHD simulations. This simulation has revealed a novel driving mechanism for spicules in which ambipolar diffusion resulting from ion-neutral interactions plays a key role. In our simulation, we often see that the upward propagation of magnetic waves and electrical currents from the low chromosphere into already existing spicules can lead to rapid heating when the currents are rapidly dissipated by ambipolar diffusion. The combination of rapid heating and the propagation of these currents at Alfvénic speeds in excess of 100 km s−1 leads to the very rapid apparent motions, and often wholesale appearance, of spicules at chromospheric and transition region temperatures. In our simulation, the observed fast apparent motions in such jets are actually a signature of a heating front, and much higher than the mass flows, which are of order 30–70 km s−1. Our results can explain the behavior of transition region "network jets" and the very high apparent speeds reported for some chromospheric spicules. © 2017. The American Astronomical Society. All rights reserved.en_US
dc.languageEN
dc.language.isoenen_US
dc.publisherInstitute of Physics Publishing Ltd.
dc.titleWhat Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?en_US
dc.typeJournal articleen_US
dc.creator.authorDe Pontieu, Bart Walter
dc.creator.authorMartinez-Sykora, Juan
dc.creator.authorChintzoglou, Georgios
cristin.unitcode185,15,3,0
cristin.unitnameInstitutt for teoretisk astrofysikk
cristin.ispublishedtrue
cristin.fulltextoriginal
cristin.qualitycode2
dc.identifier.cristin1535342
dc.identifier.bibliographiccitationinfo:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astrophysical Journal Letters&rft.volume=849&rft.spage=&rft.date=2017
dc.identifier.jtitleAstrophysical Journal Letters
dc.identifier.volume849
dc.identifier.issue1
dc.identifier.pagecount7
dc.identifier.doihttp://dx.doi.org/10.3847/2041-8213/aa9272
dc.identifier.urnURN:NBN:no-62825
dc.type.documentTidsskriftartikkelen_US
dc.type.peerreviewedPeer reviewed
dc.source.issn2041-8205
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/60178/2/De_Pontieu_2017_ApJL_849_L7.pdf
dc.type.versionPublishedVersion
cristin.articleidL7


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