A group of astronomers, including scientists from the Andalusian Institute of Astrophysics in Granada, has just discovered new details about the history of the birth of the stars that are part of the Milky Way . The images of the central part of the Milky Way that have been obtained from ESO’s VLT (Very Large Telescope) telescope show that an intense stellar outburst took place in its midst that caused some 100,000 supernova explosions .
Researchers have found that about 80% of the stars found in the central area of the Milky Way formed in the early years of the galaxy, between eight and 13.5 billion years ago. This period was followed by some 6 billion years in which very few stars were born and which were interrupted by an intense starburst that occurred about 1 billion years ago during a time span of less than 100 million years. The stars that formed in this central region had a combined mass possibly as high as a few tens of millions of suns. This discovery demolishes what had been accepted until now, which argued that the formation of stars had been continuous.
“This burst of activity, which must have led to the explosion of more than 100,000 supernovae, was probably one of the most energetic events in the entire history of the Milky Way, ” said astrophysicist Francisco Nogueras-Lara, first author of the studied and attached to the Max Planck Institute for Astronomy in Heidelberg (Germany). When an outburst occurs, many massive stars are formed. These stars are shorter-lived than lower-mass stars, reach the end of their lives much faster, and die in violent supernova explosions.
“The conditions in the region studied during this burst of activity must have resembled those of the ‘starburst’ galaxies, which form stars at rates of more than 100 solar masses per year,” adds Nogueras-Lara. Today, stars form in the Milky Way at a rate of one or two solar masses per year.
The research, published in Nature Astronomy , is funded by the European Research Council and made possible by the HAWK-I instrument of ESO’s VLT telescope in the Atacama desert (Chile). This camera is infrared sensitive and can see through dust clouds. With it, a very detailed image of the central part of the Milky Way has been obtained, which has allowed the discovery. The image shows the densest region of stars, gas and dust in the galaxy , as well as a supermassive black hole, with an angular resolution of 0.2 arc seconds. This would be comparable to watching a soccer ball in Zurich from Munich.
More than three million stars have been analyzed in the study, covering an area corresponding to more than 60,000 square light-years at the distance from the galactic center (a light-year is approximately 9.5 trillion kilometers).
