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Cosmic Crash with Dwarf Galaxy Reshaped Milky Way: Study

This spacecraft has been mapping the stellar content of our galaxy, recording the journeys of stars as they travel through the Milky Way

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Cosmic Crash with Dwarf Galaxy Reshaped Milky Way: Study. (IANS)
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A dramatic head-on collision with a dwarf galaxy, dubbed the “Gaia Sausage” galaxy, about 10 billion years ago reshaped the structure of our galaxy, the Milky Way, fashioning both its inner bulge and its outer halo, new research suggests.

The dwarf did not survive the impact. It quickly fell apart, and the wreckage is now all around us, according to the findings.

“The collision ripped the dwarf to shreds, leaving its stars moving in very radial orbits” that are long and narrow like needles, said Vasily Belokurov of the University of Cambridge and the Center for Computational Astrophysics at the Flatiron Institute in New York City.

The stars’ paths take them “very close to the centre of our galaxy. This is a telltale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed.”

The results detailed in a series of new papers in the journals the Monthly Notices of the Royal Astronomical Society, The Astrophysical Journal Letters and arXiv.org outline the salient features of this extraordinary event.

Several of the papers were led by Cambridge graduate student GyuChul Myeong. He and colleagues used data from the European Space Agency’s Gaia satellite.

Cosmic rays
Representational image. Pixabay

This spacecraft has been mapping the stellar content of our galaxy, recording the journeys of stars as they travel through the Milky Way.

Thanks to Gaia, astronomers now know the positions and trajectories of our celestial neighbours with unprecedented accuracy.

The paths of the stars from the galactic merger earned them the moniker the “Gaia Sausage,” explained Wyn Evans of Cambridge.

“We plotted the velocities of the stars, and the sausage shape just jumped out at us. As the smaller galaxy broke up, its stars were thrown onto very radial orbits. These Sausage stars are what’s left of the last major merger of the Milky Way,” Evans said.

Also Read: NASA’s Hubble finds ‘relic galaxy’ near Milky Way

The new research also identified at least eight large, spherical clumps of stars called globular clusters that were brought into the Milky Way by the Sausage galaxy.

Small galaxies generally do not have globular clusters of their own, so the Sausage galaxy must have been big enough to host a collection of clusters.

“While there have been many dwarf satellites falling onto the Milky Way over its life, this was the largest of them all,” said Sergey Koposov of Carnegie Mellon University in Pittsburgh, Pennsylvania, US. (IANS)

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New Study Shows That Binaries From Globular Clusters Can be Detected by LISA

The European Space Agency's next-generation Laser Interferometer Space Antenna (LISA) gravitational wave detector can potentially detect dozens of binary files in the globular clusters of the Milky Way, scientists say.

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In particular, these models suggest that the Kuiper Belt -- a cold region beyond the orbit of Neptune -- should contain a small fraction of rocky bodies from the inner solar system, such as carbon-rich asteroids, referred to as carbonaceous asteroids.
representational image, pixabay

The European Space Agency’s next-generation Laser Interferometer Space Antenna (LISA) gravitational wave detector can potentially detect dozens of binary files in the globular clusters of the Milky Way, scientists say.

Globular clusters are dense environments containing millions of tightly packed stars and are efficient factories for gravitational wave sources.

LISA, which is expected to be in space in 2034, will be able to detect binary sources — pairs of orbiting compact objects.

These binary sources will contain all combinations of black hole, neutron star and white dwarf components.

While 150 globular clusters have been observed so far in the Milky Way, one out of every three clusters will produce a LISA source.
Representational image. Pixabay

LISA will also be sensitive to gravitational waves of a lower frequency than those detected by the Earth-bound Laser Interferometer Gravitational-Wave Observatory (LIGO)

“LISA is sensitive to Milky Way systems and will expand the breadth of the gravitational wave spectrum, allowing us to explore different types of objects that aren’t observable with LIGO,” said lead author Kyle Kremer, a doctoral student at the Northwestern University in Illinois, US.

While 150 globular clusters have been observed so far in the Milky Way, one out of every three clusters will produce a LISA source.

Approximately eight black hole binaries will be detectable by LISA in our neighbouring galaxy of Andromeda and another 80 in nearby Virgo, the study showed.

The research, published by the journal Physical Review Letters, is the first to use realistic globular cluster models to make detailed predictions of LISA sources.

Also Read: NASA Is Sending a Helicopter to Mars in 2020 

The team used more than a hundred fully evolved globular cluster models with properties similar to those of the observed globular clusters in the Milky Way.

The models were run on Quest, Northwestern’s supercomputer cluster. This powerful resource can evolve the full 12 billion years of a globular cluster’s life in a matter of days. (IANS)