Chinese astronomers find ‘extragalactic garden’

(ORDO NEWS) — Using a giant optical telescope, astronomers from China have discovered a record number of small, compact galaxies outside the Milky Way, where star formation is occurring at a rapid pace, Xinhua news agency reported.

Using the Large Multi-purpose Wide Area Sky Spectroscope (LAMOST), a team of researchers under the auspices of the National Astronomical Observatories of the Chinese Academy of Sciences discovered 1,417 new compact galaxies, almost twice as many as previously known. The study was recently published in the Astrophysical Journal.

“This is the largest sample of new compact galaxies discovered at one time to date,” lead researcher Lo Ali said on Tuesday, adding that the previous world record for observations was just 800 galaxies.

This attracted a lot of media coverage as these newly discovered galaxies were named after vegetables and fruits, mostly based on their colors and shapes. According to Lo, the discovery included 739 Green Pea galaxies, 270 Blueberry galaxies, and 388 Blue Grape galaxies.

“The Green Pea Galaxy, for example, looked round and dense like a bean and appeared green in pseudo-color images, which is why they were called the Green Pea galaxies,” Lo added.

The Green Pea galaxies, located between 1.5 and 5 billion light-years away, are less than one tenth the size and less than one hundredth the mass of the Milky Way, but they have a very high star formation rate, about 10 times that of the Milky Way.

“Such an impressive rate of star formation was common in the early universe, but is rare these days,” said research team member Liu Xiqi.

Liu believes that the study of Green Pea galaxies will open up a new perspective for understanding the formation and evolution of galaxies in the early universe.

Blueberry galaxies are closest to Earth and more compact than Green Pea galaxies, while Blue Grape galaxies are somewhere between the other two galaxies or more distant than Green Pea galaxies.

Some Chinese media dubbed the discovery “an extragalactic fruit and vegetable garden.” But the researchers say these bright galaxies are small and faint, making observations very difficult and limited.

Law noted that the masses of these new compact galaxies range from about 310,000 to 10 billion solar masses, with the most distant being about 9 billion light-years away.

LAMOST was commissioned in 2008 to collect high-quality spectra, data that helps astronomers who study the chemical composition, density, atmosphere and magnetism of celestial bodies explore the universe. This helped discover so far the most massive stellar-mass black hole and the most lithium-rich giant star ever known.


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