![]() These include powerful jets of electrons that travel huge distances, many thousands of light years from the centres of the galaxies.Ī stream of electrons ejected from the centre of galaxy M 87. However, astronomers can study the effects of black holes on their surroundings. Black holes themselves, by definition, cannot be observed, since no light can escape from them. Prior to the launch of Hubble a handful of black hole candidates had been studied but the limitations of ground based astronomy were such that irrefutable evidence for their existence could not be obtained. Today most scientists believe that super massive black holes at the galactic centres are the "engines" that power the quasars. Hubble has observed several quasars and found that they all reside at galactic centres. Black holes and the quasar connectionīefore Hubble, quasars were considered to be isolated star-like objects of a mysterious nature. It is in the study of super massive black holes that Hubble has made its biggest contribution. Supermassive black holes, many millions of times the mass of our Sun, are of more mysterious origin, and are found at the centre of galaxies. The star's core collapses as the outer layers are blown away, leaving a small but extremely dense ball. Stellar black holes, which are around the mass of our Sun, form when very large stars explode as supernovae at the end of their lives. This has important implications for the theories of galaxy formation and evolution.īlack holes exist in different sizes. Hubble has also proved that super massive black holes are most likely present at the centres of most, if not all, large galaxies. The high resolution of Hubble made it possible to see the effects of the gravitational attraction of some of these objects on their surroundings. ![]() ![]() It is impossible to observe them directly, and astronomers had no way to test their theories until Hubble arrived. ![]() The existence of black holes has been theorised for more than 200 years. The disk of dust and gas accreting around a 300 million solar-mass black hole in NGC 7052.īlack holes are objects so dense, and with so much mass, that even light cannot escape their gravity. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |