Search results for " fisica stellare"
showing 2 items of 2 documents
The Mouse That Roared: A Superflare from the dMe Flare Star EV Lac Detected by Swift and Konus-Wind
2010
We report on a large stellar flare from the nearby dMe flare star EV Lac observed by the Swift and Konus-Wind satellites and the Liverpool Telescope. It is the first large stellar flare from a dMe flare star to result in a Swift trigger based on its hard X-ray intensity. Its peak f_X from 0.3--100 keV of 5.3x10^-8 erg/cm2/s is nearly 7000 times larger than the star's quiescent coronal flux, and the change in magnitude in the white filter is >4.7. This flare also caused a transient increase in EV Lac's bolometric luminosity (L_bol) during the early stages of the flare, with a peak estimated L_X/L_bol ~3.1. We apply flare loop hydrodynamic modeling to the plasma parameter temporal changes …
A detailed study of the rise phase of a long duration X-ray flare in the young star TWA 11B
2010
We analyzed a long duration flare observed in a serendipitous XMM-Newton detection of the M star CD-39 7717B (TWA 11B), member of the young stellar association TW Hya (~ 8 Myr). Only the rise phase (with a duration of ~ 35 ks) and possibly the flare peak were observed. We took advantage of the high count-rate of the X-ray source to carry out a detailed analysis of its spectrum during the whole exposure. After a careful analysis, we interpreted the rise phase as resulting from the ignition of a first group of loops (event A) which triggered a subsequent two-ribbon flare (event B). Event A was analyzed using a single-loop model, while a two-ribbon model was applied for event B. Loop semi-leng…