An ancient outburst of stellar formation was discovered in the central region of the Milky Way

2019-12-17

Figure: Image of the central region of the Milky Way obtained with the HAWK-I instrument installed in the VLT. The image combines observations made at three different wavelengths (blue, green, and red filters) covering the far-infrared region of the electromagnetic spectrum. Observation in this range of wavelengths allows us to observe the stars of the central region of our galaxy, which would otherwise be obscured by dust. ©ESO/Nogeras-Lara et al.

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An international team of astronomers, led by the Institute of Astrophysics of Andalusia (IAA) and with the participation of the Centro de Astrobiología (CAB, CSIC-INTA) has found evidence of a dramatic event that occurred in the Milky Way about 1 billion years ago: an outburst of stellar formation so intense that it led to the outbreak of more than one hundred thousand supernovae.

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Recent high-resolution observations obtained by the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in the central part of the Milky Way have uncovered new details on the history of the birth of stars in our galaxy. Thanks to these new observations, astronomers have found evidence of a dramatic event in the past of the Milky Way. "Our unprecedented survey of a large part of the galactic centre has given us a detailed view of the process of star formation in this region of the Milky Way," says Rainer Schsdel, a researcher at the IAA in Granada, Spain, who has led the observations. "Contrary to what was accepted so far, we discovered that the formation of stars has not been continuous," adds Francisco Nogueras-Lara, who led two new studies in the central region of the Milky Way while at the same institute in Granada.

In the study, published yesterday in the scientific journal Nature Astronomy, the team found that about 80% of the stars in the central region of the Milky Way formed in the first million years of our galaxy, between 8 billion and 13.5 billion years ago. This initial period of star formation was followed by some six billion years during which very few stars were born. "Long periods of low stellar formation involve a shortage of gas from which the massive black hole of the galactic center is nourished, pointing to the fact that it could form at the dawn of our galaxy and have been on a diet most of the time," says Francisco Najarro, researcher at the CAB and one of the authors of this study.

This period came to an end with the emergence of an intense burst of star formation some billion years ago in which, over a period of less than one hundred million years, in this central region stars were formed with a combined mass possibly as high as a few tens of millions of suns.

"The conditions in the region studied during this burst of activity must have been similar to those of the starburst galaxies, which form stars at speeds of more than 100 solar masses per year, says Nogueras-Lara, which is now based at the Max Planck Institute for Astronomy, in Heidelberg, Germany. Currently, the rate at which the Milky Way is forming stars is about one or two solar masses per year.

"This burst of activity, which should have resulted in the explosion of more than a hundred thousand supernovae, was probably one of the most energetic events in the history of the Milky Way," he adds. During a burst of stellar formation, many massive stars are created, which have a shorter lifespan than lower-mass stars and reach the end of their lives much faster, dying in violent supernova explosions.


 

Fuente: UCC-CAB

Fecha: 2019-12-17

 

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