Cosmology: Milky Way still growing (Introduction)

by David Turell , Friday, February 18, 2022, 04:41 (1009 days ago) @ David Turell

Absorbing tiny satellite galaxies:

http://www.sci-news.com/astronomy/pontus-galaxy-10564.html?utm_source=feedburner&ut...

"Our Milky Way Galaxy began forming around 12 billion years ago. Since then, it has been growing in both mass and size through a sequence of mergers with smaller galaxies.

Perhaps most exciting is that this process has not quite finished, and by using Gaia data, astronomers can see it taking place.

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“'If this process goes slowly, the stars from the merging galaxy will form a vast stellar stream that can be easily distinguished in the halo.”

“'If the process goes quickly, the merging galaxy’s stars will be more scattered throughout the halo and no clear signature will be visible.”

“'But the merging galaxy may contain more than just stars. It could also be surrounded by a population of globular clusters and small satellite galaxies.”

***

"In total, they studied 170 globular clusters, 41 stellar streams and 46 satellites of the Milky Way.

"Plotting them according to their energy and momentum revealed that 25% of these objects fall into six distinct groups.

"Each group is a merger taking place with the Milky Way. There was also a possible seventh merger in the data.

"Five — Sagittarius, Cetus, Gaia-Sausage/Enceladus, LMS-1/Wukong, and Arjuna/Sequoia/I’itoi — had been previously identified on surveys of stars.

"But the sixth was a newly-identified merger event. The authors called it Pontus, meaning the sea.

"Based upon the way Pontus has been pulled apart by the Milky Way, they estimate that it probably fell into our Galaxy some 8-10 billion years ago.

"Four of the other five merger events likely also took place around this time as well.

"But the sixth event, Sagittarius, is more recent. It might have fallen into the Milky Way sometime in the last 5-6 billion years.

"As a result, the Milky Way has not yet been able to completely disrupt it."

Comment: dhw is going to wonder in his usual way, why did God do so much with this galaxy when all He wanted was humans. The answer is humans need lots of protection from dangerous area in this galaxy as in its center. The Earth is two-thirds of the way out in the second spiral, far from the dangerous activity. God has His reasons, and this one is obvious.