Quasar
Afterlife of Stars
After a supernova explosion has occurred, sometimes a dense ball of neutrons remain in the core of the star and form what is known as neutron star. Typical neutron stars are very small, no more than 20 km in diameter. However, they have a great deal of mass, much greater than even our Sun. A neutron star can send pulses of energy and light that can be detected as radio signals and is known as a pulsar. In some regions of space, the pull of gravity is so great that nothing–not even light–can escape. These regions or black holes were possibly caused by the collapsing of very massive neutron stars. Certain distant galaxies have centers that are a hundred times brighter than ordinary galaxies. These centers are called quasars (quasi-stellar objects) and are probably very large black holes that are drawing in all sorts of glowing stellar matter..
Certain distant galaxies have centers that are a hundred times brighter than ordinary galaxies. These centers are called quasars and are probably very large black holes that are drawing in all sorts of glowing stellar matter.
Quasar
This NASA Hubble Space Telescope image shows evidence fo r a merger between a quasar and a companion galaxy. This surprising result might require theorists to rethink their explanations for the nature of quasars, the most energetic objects in the universe. The bright central object is the quasar itself, located several billion light-years away. The two wisps on the (left) of the bright central object are remnants of a bright galaxy that have been disrupted by the mutual gravitational attraction between the quasar and the companion galaxy. This provides clear evidence for a merger between the two objects. Since their discovery in 1963, quasars (quasi-stellar objects) have been enigmatic because they emit prodigious amounts of energy from a very compact source. The most widely accepted model is that a quasar is powered by a supermassive black hole in the core of a galaxy. These new observations proved a challenge for theorists as no current models predict the complex quasar interactions unveiled by Hubble. The image was taken with the Wide Field Planetary Camera-2. Credit: John Bahcall, Institute for Advanced Study, NASA.