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Type of talk
Seminar
Speaker
Subhajeet Karmakar
Affiliation
ARIES
Venue
ARIES Auditorium
Abstract

We present an in-depth study of two superflares detected on active binary system CC Eridani by Swift observatory. The first flare (F1) triggered the Burst
Alert Telescope (BAT) in the hard X-ray band on 2008 October 16, whereas the second flare (F2) triggered BAT on 2012 February 24. The rise phases of both
the flares were observed only with BAT, whereas the decay phase was observed simultaneously with X-Ray Telescope (XRT) and BAT. The e-folding decay time
indicates a faster decay in hard X-ray band than in soft X-ray. The peak X-ray luminosity for flares F1 and F2 in the 0.3–50.0 keV energy band (excluding
10–14 keV band) reached up to 3×1032 and 5×10^31 erg s^−1, which is ∼3500 and ∼600 times more than the quiescent value, respectively and larger than any
other previous flares observed on CC Eri. Spectral analysis indicates a presence of three temperature corona with first two plasma temperatures remain constant during the flares at ∼3 and ∼10 MK. The flare-temperature peaked at 342 MK and 119 MK for F1 and F2, which are ∼4 and ∼2 times more than the mini-
mum value. The abundances peaked at 2.0 and 1.2 solar abundances, which is larger than a factor ∼11 and ∼7 than quiescent state value. Using hydrodynamic loop modeling we derive loop-lengths for both flares as 1.25±0.13×10^10 cm and 1.26±0.20×10^10 cm, respectively. The Fe Kα emission at 6.4 keV was
also detected in the X-ray spectra, and we model the Kα emission feature as fluorescence from the hot flare source irradiating the photospheric iron. Our analysis indicates the flare location is in any one of the binary components withan astrocentric angle of ∼85–90◦ .

Email Speaker
subhajeet@aries.res.in
About Speaker

SRF at ARIES

Email Host
jeewan@aries.res.in
Host Name
744
Host Phone (ext/mob)
708