Abstract
ABSTRACTNear‐ultraviolet spectroscopic data obtained with the Hubble Space Telescope STIS (Space Telescope Imaging Spectrograph) instrument on the dMe flare star YZ Canis Minoris (YZ CMi) were analyzed. Flare and quiet intervals were identified from the broadband near‐UV light curve, and the spectrum of each flare was separately extracted. Mg ii and Fe ii line profiles show similar behavior during the flares. Two large flares allowed time‐resolved spectra to be analyzed, revealing a very broad component to the Mg ii k line profile in at least one flare spectrum (F9b). If interpreted as a velocity, this component requires chromospheric material to be moving with FWHM ∼ 250 km s−1, implying kinetic energy far in excess of the radiative energy. The Mg ii k flare line profiles were compared to recent radiative hydrodynamic models of flare atmospheres undergoing electron beam heating. The models successfully predict red enhancements in the line profile, with a typical velocity of a few km s−1, but do not reproduce the flares showing blue enhancements, or the strongly broadened line observed in flare F9b. A more complete calculation of redistribution into the line wings, including the effect of collisions with the electron beam, may resolve the origin of the excess line broadening.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Publications of the Astronomical Society of the Pacific
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
