title: Bright hot impacts by erupted fragments falling back on the Sun: a template for stellar accretion.
abstract: Impacts of falling fragments observed after the eruption of a filament in a solar flare on 7 June 2011 are similar to those inferred for accretion flows on young stellar objects. As imaged in the ultraviolet (UV)-extreme UV range by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, many impacts of dark, dense matter display uncommonly intense, compact brightenings. High-resolution hydrodynamic simulations show that such bright spots, with plasma temperatures increasing from ~10(4) to ~10(6) kelvin, occur when high-density plasma (>>10(10) particles per cubic centimeter) hits the solar surface at several hundred kilometers per second, producing high-energy emission as in stellar accretion. The high-energy emission comes from the original fragment material and is heavily absorbed by optically thick plasma, possibly explaining the lower mass accretion rates inferred from x-rays relative to UV-optical-near infrared observations of young stars.
authors.affiliation: Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy. reale@astropa.unipa.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Reale
authors.forename: Salvatore
authors.initials: S
authors.lastname: Orlando
authors.forename: Paola
authors.initials: P
authors.lastname: Testa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Peres
authors.forename: Enrico
authors.initials: E
authors.lastname: Landi
authors.forename: Carolus J
authors.initials: CJ
authors.lastname: Schrijver