AstroSat observations of long-duration X-ray superflares on active M-dwarf binary EQ Peg
arXiv:2111.07527 · doi:10.1093/mnras/stab3099
Abstract
We present a comprehensive study of three large long-duration flares detected on an active M-dwarf binary EQ Peg using the Soft X-Ray Telescope of the AstroSat observatory. The peak X-ray luminosities of the flares in the 0.3 - 7 keV band are found to be within ~5 - 10 x 10^{30} erg s^{-1}. The e-folding rise- and decay-times of the flares are derived to be in the range of 3.4 - 11 and 1.6 - 24 ks, respectively. Spectral analysis indicates the presence of three temperature corona with the first two plasma temperatures remain constant during all the flares and the post-flare observation at ~3 and ~9 MK. The flare temperature peaked at 26, 16, and 17 MK, which are 2, 1.3, and 1.4 times more than the minimum value, respectively. The peak emission measures are found to be 3.9 - 7.1 x 10^{53} cm^{-3}, whereas the abundances peaked at 0.16-0.26 times the solar abundances. Using quasi-static loop modeling, we derive loop-lengths for all the flares as 2.5+/-0.5 x 10^{11}, 2.0+/-0.5 x 10^{11}, and 2.5+/-0.9 x 10^{11} cm, respectively. The density of the flaring plasma is estimated to be 4.2+/-0.8 x 10^{10}, 3.0+/-0.7 x 10^{10}, 2.2+/-0.8 x 10^{10} cm^{-3) for flares F1, F2, and F3, respectively. Whereas the magnetic field for all three flares is estimated to be <100 G. The estimated energies of all three flares are ~10^{34-35} erg, putting them in a category of superflare. All three superflares are also found to be the longest duration flares ever observed on EQ Peg.
11 pages, 3 figures, 3 tables, accepted for publication in MNRAS
References in corpus (12)
- HI4PI: A full-sky HI survey based on EBHIS and GASS
- Magnetic Cycles and Rotation Periods of Late Type Stars from photometric time series
- New periodic variable stars coincident with ROSAT sources discovered using SuperWASP
- Nonthermal Hard X-ray Emission and Iron Kalpha Emission from a Superflare on II Pegasi
- Superflares on solar-type stars from the first year observation of TESS
- Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP412-31
- A Very Bright, Very Hot, and Very Long Flaring Event from the M Dwarf Binary System DG CVn
- A study of X-ray flares - I. Active late-type dwarfs
- Coronal properties of the EQ Peg binary system
- A coronal explosion on the flare star CN Leonis
- X-Ray Superflares on CC Eri
- LO Peg: surface differential rotation, flares, and spot-topographic evolution