We present preliminary results from the analysis of a long duration flare that was observed in a serendipitous XMM-Newton detection of the M star CD-39 7717 B (TWA 11 B), member of the young stellar association TW Hya. Only the rise phase (with a duration of ~35 ks) and possibly the flare peak are present in the light-curve. The decay phase was not monitored. The fluorescent iron emission line at 6.4 keV was observed during this event. As far as we are concerned, since TWA 11 B seems to have no disk, this is only the third detection of Fe photospheric fluorescence. During the flare, the X-ray flux increased a factor of ~4. Taking the light curve and the evolution of the hardness ratio into account, we interpret the rise phase as resulting from the ignition of a first group of loops (part 1) which triggered a subsequent two-ribbon flare (part 2). Part 1 is analysed using the Reale's (2007) model, since it has been assumed to be dominated by a single loop. For part 2, the diagnostic method for two-ribbon flares developed by Kopp & Poletto (1984) is applied. Loop semi-lengths of about 2.5-3.0 stellar radii are obtained. These large structures were previously detected only in very young objects, this is the first time that are detected in a more evolved (~8 Myr) star.
Crespochacón, I., Lópezsantiago, J., Reale, F., & Micela, G. (2009). Modeling the long duration rise phase of a flare detected on the M star TWA 11 B. In AIP Conference Proceedings (pp.584-587).
|Autori:||Crespochacón, I.; Lópezsantiago, J.; Reale, F.; Micela, G.|
|Titolo:||Modeling the long duration rise phase of a flare detected on the M star TWA 11 B|
|Settore Scientifico Disciplinare:||Settore FIS/05 - Astronomia E Astrofisica|
|Data di creazione:||2008|
|Nome del convegno:||COOL STARS, STELLAR SYSTEMS AND THE SUN|
|Luogo del convegno:||St Andrews, Scotland|
|Anno del convegno:||July 21-25 2008|
|Numero del convegno:||15|
|Data di pubblicazione:||2009|
|Numero di pagine:||4|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1063/1.3099180|
|Citazione:||Crespochacón, I., Lópezsantiago, J., Reale, F., & Micela, G. (2009). Modeling the long duration rise phase of a flare detected on the M star TWA 11 B. In AIP Conference Proceedings (pp.584-587).|
|Tipologia:||0 - Proceedings (TIPOLOGIA NON ATTIVA)|
|Appare nelle tipologie:||0 - Proceedings (TIPOLOGIA NON ATTIVA)|