Bright hot impacts by erupted fragments falling back on the sun: Uv redshifts in stellar accretion

Fabio Reale, Carolus J. Schrijver, Fabio Reale, Orlando, Enrico Landi, Paola Testa

Risultato della ricerca: Articlepeer review

15 Citazioni (Scopus)

Abstract

A solar eruption after a flare on 2011 June 7 produced EUV-bright impacts of fallbacks far from the eruption site, observed with the Solar Dynamics Observatory. These impacts can be taken as a template for the impact of stellar accretion flows. Broad redshifted UV lines have been commonly observed in young accreting stars. Here we study the emission from the impacts in the Atmospheric Imaging Assembly's UV channels and compare the inferred velocity distribution to stellar observations. We model the impacts with two-dimensional hydrodynamic simulations. We find that the localized UV 1600 Å emission and its timing with respect to the EUV emission can be explained by the impact of a cloud of fragments. The first impacts produce strong initial upflows. The following fragments are hit and shocked by these upflows. The UV emission comes mostly from the shocked front shell of the fragments while they are still falling, and is therefore redshifted when observed from above. The EUV emission instead continues from the hot surface layer that is fed by the impacts. Fragmented accretion can therefore explain broad redshifted UV lines (e.g., C IV 1550 Å) to speeds around 400 km s-1 observed in accreting young stellar objects.
Lingua originaleEnglish
pagine (da-a)L5-
Numero di pagine5
RivistaTHE ASTROPHYSICAL JOURNAL LETTERS
Volume797
Stato di pubblicazionePublished - 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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