BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//ZContent.net//ZapCalLib 1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20140211T103000
DTEND;TZID=Atlantic/Canary:20140211T113000
UID:iactalks-607
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/607
CREATED:2014-02-11T10:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:A Be-type star with a black hole companion
DESCRIPTION:A Be-type star with a black hole companion\nDr. Jorge Casares\n
 \nStellar-mass black holes have all been discovered through X-ray  emissio
 n, which arises from the accretion of gas from their binary  companions. C
 urrently known black holes are fed by material stripped  from a low-mass s
 tar or by the wind of a massive companion. Binary  evolution models also p
 redict the existence of black holes accreting  from the equatorial envelop
 e of rapidly spinning Be-type stars. However,  among the ~80 Be X-ray bina
 ries known in the Galaxy (~150 including the  Magellanic Clouds), only pul
 sating neutron stars have been found as  companions, which is known as the
  missing Be/black-hole X-ray binary  problem. In this talk I present the f
 irst  dynamical evidence for a  3.8-6.9 Msun black hole orbiting the Be st
 ar and gamma-ray candidate MWC  656 (=AGL J2241+4454). This discovery has 
 been allowed by the detection  of a HeII emission line from an accretion d
 isc encircling the black  hole. We find the black hole is X-ray quiescent 
 with Lx<1.6 × 10−7  times the Eddington luminosity. This im
 plies that Be binaries with  black-hole companions are difficult to detect
  by conventional X-ray  surveys and may be more abundant than predicted by
  population synthesis  models.\n \n
END:VEVENT
END:VCALENDAR