Zero Genie

Astronomers using ESO’s Very Large Telescope (VLT) have captured a stunning new image of the Milky Way’s densest region of stars, gas and dust, which also hosts a supermassive black hole. Thanks to the VLT observations, the researchers have found evidence for a dramatic event in the life of our Galaxy: a burst of star formation so intense that it resulted in over a hundred thousand supernova explosions.

Taken with the HAWK-I instrument on ESO’s Very Large Telescope, this stunning image shows the Milky Way’s central region with an angular resolution of 0.2 arcseconds. The image combines observations in three different wavelength bands. Image credit: ESO / Nogueras-Lara et al.

“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,” said Dr. Rainer Schödel, an astronomer in the Institute of Astrophysics of Andalusia.

“Contrary to what had been accepted up to now, we found that the formation of stars has not been continuous,” said Dr. Francisco Nogueras-Lara, also from the Institute of Astrophysics of Andalusia.

In the research, the scientists found that about 80% of the stars in the Milky Way central region formed in the earliest years of our Galaxy, between eight and 13.5 billion years ago.

This initial period of star formation was followed by about 6 billion years during which very few stars were born.

This was brought to an end by an intense burst of star formation around one billion years ago when, over a period of less than 100 million years, stars with a combined mass possibly as high as a few tens of million 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.

At present, the whole Milky Way is 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 are created; since they have shorter lifespans than lower-mass stars, they reach the end of their lives much faster, dying in violent supernova explosions.”

The findings are published in two papers in the journal Astronomy & Astrophysics and the journal Nature Astronomy.

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F. Nogueras-Lara et al. 2019. GALACTICNUCLEUS: A high-angular-resolution JHKs imaging survey of the Galactic centre II. First data release of the catalogue and the most detailed CMDs of the GC. A&A 631, A20; doi: 10.1051/0004-6361/201936263

F. Nogueras-Lara et al. Early formation and recent starburst activity in the nuclear disk of the Milky Way. Nat Astron, published online December 16, 2019; doi: 10.1038/s41550-019-0967-9