“BLACK HOLES” - PART 1
What is the Black Hole? It isn’t empty space as many have believed in the past but it is considered to be the most fascinating objects in space. If a star, ten times more massive than the Sun, was squeezed into a sphere about the diameter of New York City or you pack a great amount of mass into a very small area you would have a gravitational field so strong that nothing, not even light, could escape. NASA instruments have captured new pictures of these strange objects. Although the concept of an object in space that is so massive and dense that light couldn’t escape, it has been around for centuries but it wasn’t until 1967 that Princeton physicist John Wheeler, named these fascinating objects.
Einstein’s theory of general relativity predicted black holes when a massive star dies and leaves behind a small, dense remnant core. When the core’s mass is more than three times the mass of the Sun, equations showed a black hole is produced when the force of gravity overwhelms all other forces. Telescopes, that detect x-rays, light, or other forms of electromagnetic radiation, can’t directly observe black holes. Telescopes, such as those found at NASA’s space-based Chandra x-ray Observatory, are used to study the presence of black holes and their effects on surrounding space.
A process, known as accertion, occurs when a black hole passes through a cloud of interstellar matter, or is near a star and draws matter inward. X-rays are emitted that radiate into space as the attracted matter accelerates and heats up. Through recent discoveries evidence shows that black holes have a dramatic influence on surrounding space by emitting powerful gama ray bursts, devouring nearby stars, spurring the growth of new stars in some areas and stalling it in others.
As a large star dies in a supernova explosion, black holes are formed from the remnants. Smaller stars, which aren’t massive enough to trap light, become dense neutron stars. If the total mass of the star is large enough (three times the mass of the sun) then it may collapse under the influence of gravity. When the star collapses, a strange thing happens.
As the surface of the stars near an imaginary surface called the “event horizon”, time on star slows down relative to the time kept by observers far away. Time stands still when the surface reaches the event horizon and the star seizes to collapse. It is a frozen collapsing object. Stellar collisions resulted in even bigger black holes. NASA’s Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts soon after its launch in December of 2004. Data was collected later form the event’s “after glow” by Chandra and NASA’s Hubble Space Telescope. These observations led astronomers to suggest that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.
This entry was posted on Friday, January 4th, 2008 at 3:55 am and is filed under Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
