Saturday, January 14, 2023

Astrophysicists Have Revealed the True Shape of the Milky Way’s Halo of Stars

A latest research has revealed the true shape of the diffuse cloud of stars encircling the disk of our galaxy, known as the stellar halo. Previously thought to be massively spherical, like a beach ball, the new model, based on the latest observations, shows that the stellar halo is rectangular and tilted, similar to a football that has been kicked.

This research, published in The Astronomical Journal, provides perception into various astrophysical subjects, including the history and evolution of our galaxy and clues in the hunt for dark matter.

The Milky Way’s stellar halo is the visible part of what is more broadly called the galactic halo. This galactic halo is directed by invisible dark matter, whose presence is only estimated through the gravity that it applies. Every galaxy has its own nimbus of dark matter.

Comprehending the shape of the Milky Way’s stellar halo, though, has long challenged astronomers for the simple reason that we are fixed within it. The stellar halo extends out many hundred thousand light years above and below the star-filled plane of our galaxy, where our Solar System occupies.

The latest study by CFA astronomers and colleagues leverages two major datasets gathered in previous years that have explored the stellar halo as never before.

Merging these data in a flexible model that let for the stellar halo shape to emerge from all the examinations yielded the decidedly non-spherical halo — and the football shape nicely dovetails with other research to date.

The study’s outcome further chronicles just how GSE and the Milky Way interacted all those numbers of year ago. The football formation— technically called a triaxial ellipsoid — reflects the examination of two pileups of stars in the stellar halo. The pileups ostensibly created when GSE went through two orbits of the Milky Way.

Particularly, so much time has passed since the GSE-Milky Way crashed that the stellar halo stars would have been anticipated to dynamically settle into the classical, long-assumed spherical shape. The point that they haven’t likely speaks to the broader galactic halo, the team says.

Conroy’s latter point refers to the multiple dark matter detector tests now running and planned. These detectors could improve their chances of capturing an elusive interaction with dark matter if astronomers can adjudge where the substance is more heavily strenuous, galactically speaking. As Earth moves through the Milky Way, it will periodically capture these regions of dense and higher-velocity dark matter particles, improving the odds of detection.

The detection of the stellar halo’s most plausible configuration stands to move many astronomical examinations forward while filling in basic information about our place in the universe.

Reference: SciTechDaily

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