An international team led by Prof Noriyuki Matsunaga of the University of Tokyo said that a revision at a large scale is needed for the better understanding of our Milky Way Galaxy.

The Japanese, South African and Italian astronomers have discovered that there exists a big area around the centre of our own Galaxy, where there are no young stars. The work done by the team has been published in a paper in Monthly Notices of the Royal Astronomical Society.

The Milky Way is a spiral galaxy packed with several billions of stars. Our Sun is at a distance of nearly 26,000 light years from the galaxy’s centre. Calculation of the distribution of such stars is important for better understanding of how the formation of our galaxy has taken place and to shed light on its evolution.

Cepheids, the pulsating stars, are apt for this. They are very young (between 10 and 300 million years old) in comparison to our Sun (4.6 billion years old). The stars pulsate in brightness following a standard cycle, whose length is linked to the Cepheid’s luminosity, thus in case astronomers check them they can come to know how bright the star actually is, compare it with what is visible from our planet, and try to determine its distance.

In spite of this, detection of Cepheids in the inner Milky Way isn’t easy at all, because the Galaxy is packed with interstellar dust, blocking out light and hiding numerous stars from sight.

Matsunaga's team managed to deal with this by analyzing near-infrared observations made with a Japanese-South African telescope present in South Africa. They were astonished to find hardly any Cepheids in a large area spanning for thousands of light years from the Galaxy’s core.

Matsunaga explained, “We already found some while ago that there are Cepheids in central heart of our Milky Way (in a region about 150 light years in radius). Now we find outside this there is huge Cepheid desert extending out to 8000 light years from centre”.

According to a report in CS Monitor by Joseph Dussault, "An international team of researchers have detected a vast tract of space where there are no young stars. The region, described Monday in the journal Monthly Notices of the Royal Astronomical Society, begins several thousand light years from the center of the Milky Way."

But the Milky Way is thick with light-blocking cosmic dust, so it’s difficult to identify Cepheids in the inner reaches of the galaxy. A research team led by Noriyuki Matsunaga, a professor of astronomy at the University of Tokyo, used near-infrared data from South Africa’s InfraRed Survey Facility (IRSF) telescope to peer through the haze.

“I can't say I'm too surprised,” says Dan Clemens, a professor of astronomy at Boston University, in an email to The Christian Science Monitor. “Back in the 1980s, many studies found that the reservoir of molecular hydrogen gas needed for forming new stars showed a distinct dip out to three [kiloparsecs] – similar to the 8000 [light years] of today's reports – from the center of the galaxy.”

A report published in Eurek Alert revealed, "A major revision is required in our understanding of our Milky Way Galaxy according to an international team led by Prof Noriyuki Matsunaga of the University of Tokyo. The Japanese, South African and Italian astronomers find that there is a huge region around the centre of our own Galaxy, which is devoid of young stars."

The Milky Way is a spiral galaxy containing many billions of stars with our Sun about 26,000 light years from its centre. Measuring the distribution of these stars is crucial to our understanding of how our Galaxy formed and evolved. Pulsating stars called Cepheids are ideal for this.

Noriyuki Matsunaga explains: "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). Now we find that outside this there is a huge Cepheid desert extending out to 8000 light years from the centre."