XMM-Newton observations of Zeta Orionis O9.7 Ib: A Collisional Ionization Equilibrium model - AstrophysicsReportar como inadecuado




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Abstract: We present XMM-Newton observations of the O supergiant Zeta Orionis O9.7Ib. The spectra are rich in emission lines over a wide range of ionizationstages. The RGS-spectra show for the first time lines of low ion stages such asC VI, N VI, N VII, and O VII. The line profiles are symmetric and rather broadFWHM approximately 1500 km-s and show only a slight blue shift. With theXMM-epic spectrometer several high ions are detected in this star for the firsttime including Ar XVII and S XV. Simultaneous multi-temperature fits andDEM-modeling were applied to the RGS and EPIC spectra to obtain emissionmeasures, elemental abundances and plasma temperatures. The calculations showtemperatures in the range of about 0.07-0.6 keV. According to the derivedmodels the intrinsic source X-ray luminosity at a distance of 251 pcLx=1.37.03 times 10^{32} ergs-s, in the energy range 0.3-10 keV. In the bestmulti-temperature model fit, the abundances of C, N, O, and Fe are near theirsolar values, while the abundances of Ne, Mg, and Si appear somewhat enhanced.The sensitivity of the He-like forbidden and intercombination lines to ZetaOri-s strong radiation field is used to derive the radial distances at whichlines are formed. Values of 34 R-star for N VI, 12.5 R-star for O VII, 4.8R-star for Ne IX, and 3.9 R-star for Mg XI are obtained.



Autor: A.J.J. Raassen, K.A. van der Hucht, N.A. Miller, J.P. Cassinelli

Fuente: https://arxiv.org/







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