Gaia Spies its First Supernova
The European Space Agency’s Gaia space astrometry mission has spotted its first supernova. The powerful stellar explosion was spotted in a galaxy 500 million light-years away, and has been named Gaia14aaa. Gaia detected the supernova by observing a sudden increase in the galaxy’s brightness between observations separated by a month.
Gaia repeatedly scans the entire sky, working to create a detailed 3D map of a billion stars. Those stars will all be observed an average of 70 times over the course of the five year mission. This will not only help create a catalog that precisely charts position, distances and movements of the stars, but will also allow Gaia to detect transient events. Such activities can include flares marking the birth of stars, black holes feeding, and, as in this case supernovae.
Based on the observed spike in brightness detected, astronomers thought they had found a supernova, but they needed more data to confirm the discovery. Based on the position of the bright spot they saw, they thought it was unlikely that it was related to a central black hole in the galaxy. Spectral analysis, also collected by Gaia, showed researchers the presence of iron and other elements typically found in supernovae. Additionally, the blue part of the spectrum appeared significantly brighter than the red part, indicating that this was not only a supernova, but likely a “Type Ia” supernova. These stellar explosions represent the demise of a white dwarf that is part of a binary system with a larger companion star. The compact white dwarf is very dense, and draws material away from the companion, growing until it reaches critical mass and explodes as a Type Ia supernova.
Further confirmation came from ground-based observations using the Isaac Newton Telescope (INT) and the Liverpool Telescope on La Palma, in the Canary Islands. High resolution spectra obtained with the INT confirmed that the explosion corresponds to a Type Ia supernova, and also provided an estimate of its distance. The distance matches to the galaxy where Gaia observed the spike in brightness.
Though supernova explosion are rare events in any single galaxy, with Gaia mapping the entire sky, this detection is the first of many to come. Astronomers believe that once they have optimized their detection software, Gaia will discover an average of three supernovae every day.
For an earlier post of ours on the Gaia mission, go here.
Image caption: Artist’s impression of the Type Ia supernova detected by Gaia.
Image credit: ESA/ATG medialab/C. Carreau