A vast tract of space near the center of the Milky Way — in an area
called the inner disk — is completely devoid of young stars, new
research shows.
The Milky Way, which hosts Earth's solar system, is a spiral galaxy
containing billions and billions of stars. By measuring the distribution
of these stars, astronomers can better understand how the Milky Way
formed and developed over time.
Young stars called Cepheids are good growth markers because they regularly pulsate in brightness
and the pulsations are tied to their overall luminosity. This means
astronomers can monitor the duration of bright periods and estimate the
stars' distance from Earth based on how bright they appear. But in the
Milky Way's inner disk, which extends for 8,000 light-years from the
galactic core, researchers haven't found any of those young stars, and
that observation challenges current theories on Milky Way formation,
officials said in a statement from the Royal Astronomical Society.
"The current results indicate that there has been no significant star
formation in this large region over hundreds of millions years,"
Giuseppe Bono, co-author of the new research and astronomer at the Rome
Observatory, said in the statement.
This lack of Cephids had not been seen before, because thick,
light-blocking cosmic dust in the inner regions of the Milky Way block
astronomers' view from Earth and make it difficult to spot the pulsating
stars. But by using near-infrared data from a Japanese-South African
telescope, the researchers were able to get a clearer view.
Previous studies found Cepheids in the heart of the Milky Way, said
Noriyuki Matsunaga, lead author of the new work from the University of
Tokyo. "Now, we find that outside this there is a huge Cepheid desert
extending out to 8,000 light years from the center," he said in the
statement.
With the Milky Way itself
measuring about 100,000 light-years across, the researchers noted that
this stellar desert comprises a lot of empty space.
"Our conclusions are contrary to other recent work but in line with the
work of radio astronomers who see no new stars being born in this
desert," Michael Feast, co-author of the new research and astronomer
from the South African Astronomical Observatory, said in the statement.
The new work was published June 27 in the Monthly Notices of the Royal Astronomical Society.
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