Abstract
Stars of spectral type 'Be' are often found with neutron stars or other evolved analogues, but a black-hole companion has never been spotted before. Optical emission from a black hole's surroundings has given it away. See Letter p.378 Binary evolution models predict the existence of black holes accreting from the equatorial envelope of rapidly spinning 'B-emission' or 'Be' stars — young, blue irregular variables that show the characteristic spectral emission lines of hydrogen. So far, however, most of the compact stellar companions found in Be X-ray binaries have been identified as neutron stars. A few contain subdwarf stars but until now none had been found to host a black hole. The picture changes with the discovery of an unprecedented He II 4,686 A optical emission line in the spectrum of an accretion disk around the companion to the Be star MWC 656. This, together with other information, points to the presence a black hole of 3.8 to 6.9 solar masses.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
