Illustrazione del sistema binario M33 X-7. L’immagine in basso a sinistra è stata ottenuta con l’osservatorio Chandra (in blu) e HST. Gli oggetti brillanti che si osservano nell’inserto sono stelle giovani e massicce attorno a M33 X-7 e l
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
Will M. Farr,
Bart Willems &
Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
Department of Astronomy, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1221, USA
Jerome A. Orosz
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
Tassos Fragos &
V.K. and B.W. designed the study. F.V. led the project, performed the single and binary star evolution calculations, and developed the code to perform the orbital evolution after black-hole formation. V.K. and B.W. collaborated with F.V. in each step of the project. E.G. maintained, updated and extended the stellar evolution code used, and collaborated with F.V. in performing the calculations. W.M.F. determined the correction to the star’s luminosity and surface temperature due to the inclination of the system. T.F. led the theoretical analysis of the black-hole spin. J.A.O. performed the analysis of the observational data on M33 X-7 using the ELC code for the full distance uncertainty. J.L. recalculated the black hole’s spin at different distances. All authors discussed the results and made substantial contributions to the manuscript.
Competing financial interests
The authors declare no competing financial interests.