A rift in the Milky Way associated with galactic collision

A rift in the Milky Way associated with galactic collision

A graphic representation of the Milky Way showing its crooked outer edges. Credit: Xinlun Cheng

When most of us imagine the shape of the Milky Way, the galaxy that contains our own sun, and hundreds of billions of other stars, we think of a central mass surrounded by a flat disk of stars revolving around it. However, astronomers know that the disk structure is skewed, rather than symmetrical, more like the edge of a fedora, and that the skewed edges are constantly moving around the outer edge of the galaxy.

“If you’ve ever seen an audience in a stadium, it’s very similar to the concept,” said Xinlun Cheng, a graduate of astronomy at the University of Virginia’s College and Graduate School of Arts & Sciences. “Every member of the audience gets up and then sits down at the right time and in the right order to create the wave as it goes around the stadium. That’s exactly what stars do in our galaxy. Only in this case, “as the wave revolves around the galaxy’s disk, the galaxy also revolves around the center of the galaxy. In terms of the sports fan analogy, it’s like the stadium itself revolves.”

The cause of the rift is the subject of debate. Some researchers suggest that the phenomenon is the result of the instability of the galaxy itself, while others claim that it is the remnant of a collision with another galaxy in the distant past.

A recent article published in the Astrophysical Journal by Cheng, who studies the movements of the stars, and his colleagues, Borja Anguiano, a postdoctoral research fellow at UVA, and Steve Majewski, a professor in the Department of Astronomy at the College, can finally calm the debate. .

Using data from the Gaia Space Observatory, a satellite launched by the European Space Agency in 2013 to measure the positions, distances and movements of billions of stars and information from APOGEE, an infrared spectrograph developed by UVA to investigate chemical composition and motions of stars. , astronomers now have the tools to observe the motions of the stars in the Milky Way with an unprecedented degree of accuracy.

“By combining information from the APOGEE instrument with information from the Gaia satellite, we begin to understand how the different components of the galaxy move,” said Anguiano, who is interested in the movements of the components and what the phenomena may be. have. originally caused those movements to occur.

“It is now possible to characterize these movements with unprecedented accuracy due to the precision and statistical robustness of the vast catalog of stars examined by the Gaia satellite,” Majewski explained. “Meanwhile, our own large database of sterochemicals generated by APOGEE offers us the unique ability to deduce star ages. This enables us to investigate how stars of different ages participate in the warp and can make us zero to creation. then give us an idea of ​​why it was created. ‘

A rift in the Milky Way associated with galactic collision

The spiral system M81, which is similar in size and shape to our own galaxy, the Milky Way. Credit: NASA

Using this data, Cheng and his colleagues developed a model that characterizes the parameters of the galactic warp, where it starts in the outer disk, how fast the warp moves, and the shape of the warp. The model helped them determine that the warp, which does not affect our own sun but now surpasses our solar system at speeds that allow it to make a full turn around the galaxy every 450 million years, is not the result of the Milky Way’s own internal mass. Instead, it is the remnant of gravity on the Milky Way’s disk through the nearby passage of a satellite system, possibly the Sagittarius Dwarf Spheroidal Milky Way, about 3 billion years ago.

“We can still see the disk shaking from our galaxy,” Anguiano said.

The data the team collects from the new instruments available to astronomers may be just the beginning of a new wave of discoveries about our universe and how it came to be.

‘We are entering an era in astronomy, especially in galactic astronomy, in which we measure the motion of the stars at such a precise level that we can map their orbits in the past and begin to understand how they may have been affected. ‘in the past and how other galaxies approaching us interacted with stars when they were born,’ ‘Anguiano said. “This level of precision has opened a new door to understanding our galaxy’s past and how it was composed.”

The article, “Exploring the Galactic Warp through Asymmetries in the Kinematics of the Galactic Disk”, by Cheng and his colleagues, is in the December issue of the Astrophysical Journal.


The galaxy is blowing


More information:
Xinlun Cheng et al. Exploration of the galactic warp by asymmetry in the kinematics of the galactic disk, The Astrophysical Journal (2020). DOI: 10.3847 / 1538-4357 / abc3c2

Provided by the University of Virginia

Quotation: A galaxy collision related to galactic collision (2021, February 5) was detected on February 6, 2021 from https://phys.org/news/2021-02-warp-milky-linked-galactic-collision .html

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