SPECTROSCOPIC STUDY OF THE ULX-PULSAR NGC 7793 P13

Abstract

We will re-analyze the archived data of NGC 7793 P13 obtained with the ESO-VLT telescope in 2009-2011. The spectra contain a bright HeII λ4686 emission line, the nature of the variability of which indicates that it is formed in a supercritical accretion disk. We are constructing a radial velocity curve of this line, an analysis of which, together with data from the literature, allowe us to obtain the following system parameters: the semi-amplitude of the radial velocity of the accretor is 48 ± 10kms−1 , the donor massfunction is 0.738 M, and the orbit inclination is 20.3 ± 1◦