An incredibly detailed survey of the Milky Way’s core has shed light on our galaxy’s explosive legacy of star birth. According to the authors of the study, their results disagree with the widely accepted view that stars formed in the central region at a continual pace.
The Milky Way is estimated to play host to roughly 100 thousand million stars. On a clear night away from city lights they fill the sky, and the heart of our galaxy can be seen as a light, blurry streak arcing overhead. Counter intuitively, it is estimated that just one to two solar masses worth of stars are created per year in the Milky Way today.
Astronomers had previously believed that this mind-bending population of stellar bodies was created at a continuous rate. However, a new study published in the journal Nature Astronomy suggests that the star birthing history of our galaxy has a more staggered and dramatic nature.
The new research centered around an analysis of exquisitely detailed images of the Milky Way’s center captured using the European Southern Observatory’s Very Large Telescope (VLT), upon which was mounted the HAWK-I instrument. HAWK-I is a near infrared wide-field imager, capable of observing swathes of the night sky in impressive detail.
HAWK-I’s ability to detect and capture light that exists in the infrared part of the electromagnetic spectrum makes it a useful tool for probing regions of our galaxy that are permeated by vast clouds of cosmic dust. These clouds block and scatter many wavelengths of light, but infrared light can pass through largely unhindered.
The images were taken as part of the GALACTICNUCLEUS survey, which studied over three million stars spread over 60,000 square light-years.
An analysis of the survey data revealed that a vast population of stellar bodies burst into life 8-13.5 billion years ago. This period of frenzied star birth, during which roughly 80 percent of the Milky Way’s stars were created, was followed by a six billion year drought during which few stars were created in the galactic center.
This tranquil period came to an end about one billion years ago. In the 100 million years that followed, a new population of stellar bodies were formed that had the combined mass of tens of millions of Suns. Since this flurry of activity, star birth has continued at a slower pace.
“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,” says Francisco Nogueras-Lara, who led two new studies of the galactic center while at the Institute of Astrophysics of Andalusia in Granada. “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,”
The reason that some of the stars exploded relatively soon after their creation is linked to their mass. Intermediate mass stars such as our Sun are able to shine for around 10 billion years, however very massive stars use up their fuel at a much faster rate. Because of this, their lives are much shorter, and end in dramatic supernovae explosions, as opposed to our Sun, which will end its life as a slowly cooling white dwarf.
The papers [ 1, 2] have been published in the journal Nature Astronomy.
The video below zooms in on the Milky Way’s central region from the perspective of Earth.
Source: ESO