astronomy

Hidden X-ray source found in Milky Way

PENN STATE (US) — Astronomers have discovered an X-ray emitting object that had been hidden inside the constellation Centaurus.

The object—a binary system—was revealed recently when an instrument on the International Space Station named MAXI (Monitor of All-Sky X-ray Image) on the Japanese Experiment Module “Kibo” caught it in the act of erupting with a massive blast of X-rays known as an X-ray nova.

The MAXI mission team quickly alerted astronomers worldwide to the discovery of the new X-ray source at 2 a.m. EDT on Wednesday, Oct. 20, and NASA’s Swift Observatory quickly conducted an urgent “target-of-opportunity” observation nine hours later, which allowed for the location of the X-ray nova to be measured accurately.

“The collaboration between the MAXI and Swift teams allowed us to quickly and accurately identify this new object,” says Jamie Kennea, the Swift X-ray Telescope instrument scientist at Penn State who is leading the Swift analysis. “MAXI and Swift’s abilities are uniquely complementary, and in this case have provided a discovery that would not have been possible without combining the knowledge obtained from both.”

The Swift detection confirmed the presence of the previously unknown bright X-ray source, which was named MAXI J1409-619.

“The Swift observation suggests that this source is probably a neutron star or a black hole with a massive companion star located at a distance of a few tens of thousands of light years from Earth in the Milky Way,” says David Burrows, professor of astronomy and astrophysics at Penn State and the lead scientist for Swift’s X-ray Telescope.

“The contribution of Swift’s X-ray Telescope to this discovery is that it can swing into position rapidly to focus on a particular point in the sky and it can image the sky with high sensitivity and high spatial resolution.”

“MAXI has demonstrated its capability to discover X-ray novae at great distances,” says Kazutaka Yamaoka, assistant professor at Aoyama Gakuin University and a member of the MAXI team. “The MAXI team is planning further coordinated observations with NASA satellites to reveal the identity of this source.”

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