In our galaxy's center, scientists see a void

An artist's conception of the implied distribution of young stars, represented here by Cepheids shown as blue stars, plotted on the background of a drawing of the Milky Way. With the exception of a small clump in the Galactic center, the central 8,000 light years appear to have very few Cepheids, and hence very few young stars. (The University of Tokyo)

The Milky Way has a huge region that is evidently no place for youngsters. The center of our galaxy has an enormous void that surprisingly lacks young stars, astronomers announced last week.

Using a telescope in South Africa, the astronomers focused their study on a type of star called cepheids. These are youthful stars— just between 10 and 300 million years old, compared to the 4.6 billion years our Sun has under its belt. Cepheids are a key type of star for scientists to study, because they pulsate, and the pulsation time is linked to their brightness, allowing astronomers to figure out how far away the star is.

But when the scientists studied the inner part of our galaxy, they discovered a dearth of these young stars in a huge portion of the Milky Way’s center outside of its core.

"We already found some while ago that there are Cepheids in the central heart of our Milky Way (in a region about 150 light years in radius),” Noriyuki Matsunaga, a professor at the University of Tokyo and the leader of the team behind the discovery, said in a statement. “Now we find that outside this there is a huge Cepheid desert extending out to 8000 light years from the centre.”

The finding gives scientists more information about the structure of our galaxy— an enormous spiral, made up of billions of stars, that measures about 100,000 light years across. The Earth is located about 26,000 light years from the center.

"The current results indicate that there has been no significant star formation in this large region over hundreds of millions years," Giuseppe Bono, a coauthor of the new study, said in the statement. "The movement and the chemical composition of the new Cepheids are helping us to better understand the formation and evolution of the Milky Way."

The study was published in the journal the Monthly Notices of the Royal Astronomical Society.

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