English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Sunspot observations in chromospheric spectral lines have revealed theexistence of short-lived linear bright transients, commonly referred to aspenumbral micro-jets (PMJs). Details on the origin and physical nature of PMJsare to large extend still unkown. We aim to characterize the dynamical natureof PMJs to provide guidance for future modelling efforts. We analyze highspatial (0.1 arcsec) and temporal resolution (1 s) Ca II H filtergram (0.1 nmbandwidth) observations of a sunspot obtained on two consecutive days with theSwedish 1-m Solar Telescope. We find that PMJs appear to be the rapidbrightening of an already existing (faint) fibril. The rapid brightening is thefast increase (typically less than 10 s) in intensity over significant length(several 100s of km) of the existing fibril. For most PMJs, we cannot identifya clear root or source from where the brightening appears to originate. Afterthe fast onset, about half of the PMJs have a top that is moving with anapparent velocity between 5 and 14 km/s, most of them upwards. For the otherPMJs, there is no significant motion of the top. For about a third of the PMJswe observe a splitting into two parallel and co-evolving linear features duringthe later phases of the lifetime of the PMJ. We conclude that mass flows canplay only limited role in the onset phase of PMJs and that it is more likelythat we see the effect of a fast heating front.

Penumbral micro-jets at high spatial and temporal resolution