Sagittarius a*
Sagittarius A*: the center of our home
By Martha Mendoza
Professor Norman Sperling
Introduction to Astronomy FPF 2012
November 5, 2012
Sagittarius A*: The center of our home
The big dates were February 13 and 15 of the year 1974, when Bruce Balick and Robert Brown worked with the baseline interferometer at the National Radio Astronomy Observatory and discovered a radio source coming from the center of the Milky Way. They named the source Sagittarius A* (Sagittarius A star) but they did not know what to make of it. This radio source was found to emit synchrotron radiation, which occurs when charged particles are accelerated in a curved orbit around an object. The object was also found to be extremely massive, dense and immobile as a result of its gravitation. Although Balick and Brown were not sure of what this phenomena could be, they had a potential candidate that fit the characteristics of Sagittarius A*’s behavior.
Space being warped due to an extremely massive object
Space being warped due to an extremely massive object
The idea of black holes is nothing new. It goes back to John Michell whom in 1784 published a letter he sent to Henry Cavendish where he explains the effect that gravity has on light. He is now credited for being the first to consider the case of a supermassive object that prevents light from escaping. He called these objects “dark stars”, which we now know as black holes. With later knowledge of the theory of relativity, scientists were able to find out that when so much matter is concentrated in a small region, gravitational forces are so strong and space so extremely warped that light is no longer just being bent, but trapped inside the object (see image on the left). Although the concept of black holes is relatively old, the findings and research on them are quite new. After being ignored for almost a century, the idea of black holes was again being explored thanks to Einstein’s general theory of relativity. Of course,
By Martha Mendoza
Professor Norman Sperling
Introduction to Astronomy FPF 2012
November 5, 2012
Sagittarius A*: The center of our home
The big dates were February 13 and 15 of the year 1974, when Bruce Balick and Robert Brown worked with the baseline interferometer at the National Radio Astronomy Observatory and discovered a radio source coming from the center of the Milky Way. They named the source Sagittarius A* (Sagittarius A star) but they did not know what to make of it. This radio source was found to emit synchrotron radiation, which occurs when charged particles are accelerated in a curved orbit around an object. The object was also found to be extremely massive, dense and immobile as a result of its gravitation. Although Balick and Brown were not sure of what this phenomena could be, they had a potential candidate that fit the characteristics of Sagittarius A*’s behavior.
Space being warped due to an extremely massive object
Space being warped due to an extremely massive object
The idea of black holes is nothing new. It goes back to John Michell whom in 1784 published a letter he sent to Henry Cavendish where he explains the effect that gravity has on light. He is now credited for being the first to consider the case of a supermassive object that prevents light from escaping. He called these objects “dark stars”, which we now know as black holes. With later knowledge of the theory of relativity, scientists were able to find out that when so much matter is concentrated in a small region, gravitational forces are so strong and space so extremely warped that light is no longer just being bent, but trapped inside the object (see image on the left). Although the concept of black holes is relatively old, the findings and research on them are quite new. After being ignored for almost a century, the idea of black holes was again being explored thanks to Einstein’s general theory of relativity. Of course,