The stellar-wind envelope around the supernova XRF-GRB060218-SN2006aj massive progenitor star - AstrophysicsReportar como inadecuado

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Abstract: In BTA spectra of the supernova SN2006aj, identified with the X-ray flashXRF and gamma-ray burst XRF-GRB060218-SN2006aj, we detected detailsinterpreted as hydrogen lines, which is a sign of stellar-wind envelope arounda massive progenitor star of the gamma-ray burst. Results of modeling two earlyspectra obtained with the BTA in 2.55 and 3.55 days after the explosion of TypeIc supernova SN2006aj z=0.0331 are presented. The spectra were modeled in theSobolev approximation with the SYNOW code Branch et al. 2001; Elmhamdi et al.2006. In the spectra of the optical afterglow of the X-ray flash XRF-GRB060218we detected spectral features interpreted as 1 the H alpha PCyg profile forthe velocity 33000 km s$^{-1}$ - a wide and almost unnoticeable deformation ofcontinuum in the range of $\simeq5600 - 6600\AA$ for the first epoch 2.55days and 2 a part ``remnant- of the H alpha PCyg profile in absorptionblueshifted by 24000 km s$^{-1}$ - a wide spectral feature with a minimum at$\simeq6100\AA$ the rest wavelength for the second epoch 3.55 days. Takinginto consideration early BTA observations and spectra obtained with othertelescopes ESO Lick, ESO VLT, NOT before 2006 Feb. 23 UT, it can be said thatwe observe evolution of optical spectra of Type Ic core-collapse supernova SN2006aj during {\it transition} from the short phase related to the shockbreakout to outer layers of the stellar-wind envelope to spectra of the phaseof increasing brightness corresponding to radioactive heating. Signs ofhydrogen in spectra of the gamma-ray burst afterglow were detected for thefirst time.

Autor: E. Sonbas, A.S. Moskvitin, T.A. Fatkhullin, V.V. Sokolov, A. Castro-Tirado, A. de Ugarte Postigo, J. Gorosabel, S. Guziy, M. Jeli


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