At a first glance, the globular cluster NGC 1783 looks like a high concentration of pockmarks of light bursting their way through a black expanse. Located roughly 160,000 light-years from the Earth, the massive stellar cluster boasts a mass equivalent to 170,000 suns. The cluster is one of the biggest and brightest located in the Large Magellanic Cloud satellite galaxy.
Previously, scientists thought stellar clusters formed in a single outburst from a progenitor cloud. But by studying clusters like NGC 1783, scientists from the Kavli Institute for Astronomy and Astrophysics, the National Astronomical Observatories of the Chinese Academy of Sciences, Northwestern Univ., and the Adler Planetarium have found that globular clusters can give birth to second and third sets of thousands of sibling stars after the initial progeny. Their research was published in Nature.
According to the researchers, NGC 1783 bore populations of stars around 4.1 billion years ago, 890 million years ago, and 450 million years ago.
“Such clusters could have accreted sufficient gas from new stars if they had orbited in their host galaxies’ gaseous disks throughout the period between their initial formation and the more recent bursts of star formation,” the researchers wrote. “This process may eventually give rise to ubiquitous multiple stellar populations in globular clusters.”
NGC 1783 was first observed by English astronomer John Herschel in 1835.
The researchers also studied NGC 1696, which is located in the Large Magellanic Cloud, and NGC 411, located in the Small Magellanic Cloud. Each of the star clusters is between 1 and 2 billion years old. According to Space.com, NGC 1696 is about 160,000 light-years from Earth and is 50,000 solar masses; NGC 411 is about 190,000 light-years away and about 32,000 solar masses.
At first, the researchers considered the theory that globular clusters retain enough gas and dust to create new stars throughout their lifetimes. However, this explanation was refuted by the idea that massive stars in globular clusters live for about 10 million years before exploding as supernovae. This would cause any gas and dust nearby to be blown away.
The sweeping theory adopted by the researchers was actually proposed in 1952.
“We have now finally shown that this idea of clusters forming new stars with accreted gas might actually work,” said Richard de Grijs, of the Kavli Institute for Astronomy and Astrophysics, “and not just for the three clusters we observed for this study, but possibly for a whole slew of them.”
