Abstract :
This composite image shows the expanding remains of a supernova explosion in the Milky Way: The supernova remnant G1.9+0.3. NASA´s Chandra X-ray Observatory image, obtained in early 2007, is shown in orange and the radio image from NRAO´s Very Large Array (VLA) from 1985 is in blue. The difference in size between the two images gives clear evidence for expansion, allowing the time since the original supernova explosion (about 140 years) to be estimated. This makes the original explosion the most recent supernova in the Galaxy as measured in Earth´s time-frame (referring to when events are observable from Earth). Equivalently, this is the youngest known supernova remnant in the Galaxy (140 years old), easily beating the previous record of about 330 years for Cassiopeia A. The rapid expansion and young age for G1.9+0.3 was recently confirmed by a new VLA image obtained in early 2008. The original supernova explosion was not visible to the naked eye 140 years ago, because it occurred close to the center of the Galaxy and is embedded in a dense field of gas and dust. This made the supernova about a trillion times fainter, in optical light, than if it had been unobscured. However, X-rays and radio waves from the resulting supernova remnant easily penetrate this dust and gas.
