Astronomers using ESO’s Very Large Telescope (VLT) have captured a hi-res image of the central region of the Milky Way. It uncovers an ancient starburst.
The Milky Way’s center is the densest region of stars, gas, and dust and also contains a supermassive black hole.
While investigating that region, astronomers have found evidence for a dramatic event in the life of the Milky Way.
Using a special infrared-sensitive camera, the VLT captured a high-resolution image uncovering an ancient ‘starburst’ caused by more than 100,000 supernovae.
“Our unprecedented survey of a large part of the Galactic center has given us detailed insights into the formation process of stars in this region of the Milky Way,” says Rainer Schödel from the Institute of Astrophysics of Andalusia in Granada, Spain, who led the observations.
“Contrary to what had been accepted up to now, we found that the formation of stars has not been continuous,” adds Francisco Nogueras-Lara, who led two new studies of the Milky Way central region while at the same institute in Granada.
The study suggests the ‘starburst’ occurred one billion years ago after a slow period.
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The team found that about 80% of the stars making up the Milky Way’s central region formed in the earliest years of our galaxy, between eight and 13.5 billion years ago.
This initial period of activity was then followed by about 6 billion years during which very few stars were born.
However, this quiet period came to an end by an intense burst of star formation around one billion years ago. During that time, over a period of fewer than 100 million years, stars with a combined mass equivalent to tens of millions of Suns formed in this central region.
“The conditions in the studied region during this burst of activity must have resembled those in ‘starburst’ galaxies, which form stars at rates of more than 100 solar masses per year,” Dr. Nogueras-Lara said.
The whole Milky Way is now forming stars at a rate of about one or two solar masses per year.
“This burst of activity, which must have resulted in the explosion of more than a hundred thousand supernovae, was probably one of the most energetic events in the whole history of the Milky Way,” Dr. Nogueras-Lara added.
During a starburst, many massive stars form. Since they have shorter lifespans than their lower-mass counterparts they reach the end of their lives much faster. Therefore, dying in violent supernova explosions.
The researchers published their study today in Nature Astronomy.