Detail View: NASA Astronomy Picture of the Day Collection: Cyg X-1: Can Black Holes Form in the Dark?

Title: 
Cyg X-1: Can Black Holes Form in the Dark?
Explanation: 
The formation of a black hole [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ black_holes.html ] from the collapsing core of a massive star is thought to be heralded by a spectacular supernova explosion. Such an extremely energetic collapse is also a leading explanation [ http://arxiv.org/abs/astro-ph/0304173 ] for the mysterious cosmic gamma-ray bursts [ http://antwrp.gsfc.nasa.gov/apod/ap020228.html ]. But researchers now suggest that the Milky Way's most famous black hole, Cygnus X-1 [ http://hyperphysics.phy-astr.gsu.edu/hbase/astro/ blkbin.html#c2 ], was born when a massive star collapsed -- without any supernova explosion [ http://arxiv.org/abs/astro-ph/0305205 ] at all. Their dynamical evidence is summarized in this color image of a gorgeous region in Cygnus [ http://imagine.gsfc.nasa.gov/YBA/cyg-X1-mass/ cygX1-more3.html ], showing Cyg X-1 and a cluster of massive stars (yellow circles) known as Cygnus OB3. Arrows compare the measured direction and speed of Cyg X-1 and the average direction and speed of the massive stars of Cyg OB3. The similar motions indicate that Cyg X-1's progenitor star was itself a cluster member and that its path was not altered at all when it became a black hole [ http://chandra.harvard.edu/xray_sources/ blackholes_stellar.html ]. In contrast, if Cyg X-1 were born in a violent supernova it would have likely received a fierce kick [ http://hubblesite.org/newscenter/archive/2002/30/ ], changing its course. If not a supernova, could the formation of the Cyg X-1 black hole have produced a dark gamma-ray burst in the Milky Way [ http://www.pbs.org/wgbh/nova/gamma/milkyway.html ]?
Credit and Copyright: 
I. F. Mirabel [ http://www.iafe.uba.ar/astronomia/mirabel/mirabel.html ] and I. Rodrigues (IAFE [ http://www.iafe.uba.ar/ ], SAp/CEA [ http://dphs10.saclay.cea.fr/Phys/Sap/ ])
facet_where: 
Goddard Space Flight Center (GSFC)
facet_what: 
Cygnus
original url: 
http://antwrp.gsfc.nasa.gov/apod/ap050402.html
UID: 
SPD-APOD-ap050402