Cosmology: Milky Way is still not completely understood (Introduction)

by David Turell , Wednesday, November 25, 2020, 00:03 (1461 days ago) @ David Turell

Some stars are not acting like they should, theories have to adapt:

https://www.universetoday.com/148850/some-of-the-milky-ways-oldest-stars-arent-where-th...

"One of the ways we categorize stars is by their metallicity. That is the fraction of heavier elements a star has compared to hydrogen and helium. It’s a useful metric because the metallicity of a star is a good measure of its age.

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"Since we can determine the metallicity of a star by observing its spectrum, we know the overall metallicity of stars, both in our galaxy and others. We can therefore group stars into metallicity “populations.” This is done by defining the hydrogen to iron ratio, [Fe/He], on a logarithmic scale setting our Sun as the zero point.

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"Using Australia’s SkyMapper Southern Survey, the team identified 475 stars with a [Fe/He] ratio less than one-thousandth that of our Sun. We would expect them to be halo stars, but when the team calculation the positions and orbits of these stars using data from Gaia they found that 11% of them orbit within the galactic plane. Their orbits are also very circular, similar to the orbit of the Sun. This is surprising and goes against predictions of current galactic evolution models.

"Large sky surveys of our galaxy are certain to revolutionize our understanding of the Milky Way. As even these early results show, it is clear we still have much to learn."

Comment: Lesson is that we still have lots to learn, which really means today's thoughts about how and/or why God did what He seems to have done may be entirely off the mark.