An Ancient Part of The Milky Way Is Much Older Than We Ever Knew

Astronomers think that part of the Milky Way is older than they thought. The disk is two billion years older than we thought.

The thick disk formed after the Big bang.

The history of the Milky Way was pieced together by a pair of astronomer. The results are based on the data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. Subgiant stars are the key to this discovery.

A time-resolved picture of our Milky Way's early formation history is online in the journal Nature. The authors are from the Max-Planck Institute for Astronomy.

It is difficult to determine a star's age. The composition of a star is important to finding its age. The more accurate the astronomer is, the more accurate they can determine its age.

The early Universe was mostly hydrogen and helium. When stars die and explode, elements heavier than hydrogen and helium are released into the Universe. Every element is heavier than the two primordial elements.

The view is from the edge-on view. Stefan Payne-Wardenaar is a member of the MPIA.

Stars with lower metallicity were formed when hydrogen and helium were plentiful. Astronomers know that stars with hydrogen and helium are older. They know that stars with higher proportions of metals must be younger.

The holy grail of astronomy is precision age measurement. The stars were determined by more than just metallicity. Subgiants are a type of star.

The subgiant phase of a star's life is brief and can be used to determine a star's age. Subgiants no longer produce energy in their core. fusion has moved into a shell around the core.

The pair of scientists used LAMOST data to determine the metallicity of about 250,000 stars in different parts of the Milky Way. The precise position and brightness data for 1.5 billion stars was given by Gaia.

The increased accuracy in this study is due to the increased accuracy of the Gaia mission. Astronomers used to work with stellar age uncertainties between 20 to 40 percent. It means that ages could be off by one billion years.

All this has changed because of Gaia. The current data release from the mission is called Gaia EDR 3 or Early Data Release 3. 3D positions of over 320,000 stars are given by EDR3. It gives high-precision measurements of the stars.

The age of a subgiant star can be determined using the data from LAMOST and Gaia.

The subgiants are spread throughout the different parts of the Milky Way, allowing researchers to piece together the ages of the other components.

There are two distinct phases in our history. The thick disk began to form stars about 0.8 billion years ago. The inner regions of the halo started to develop as well.

The star formation in the thick disk was completed after two billion years. The dwarf galaxy is named after a constellation of stars.

The dwarf galaxy is not shaped like a sausage. Its name comes from the stars being plotted on a velocity chart. The thick disk was created by the gas that came with it when it merged with the Milky Way.

The halo of stars was filled by the merger. Astronomers think the remnant core of the Gaia Sausage might be the globular cluster. One of the most massive clusters is called NGC 2808.

The star formation lasted about 4 billion years. The gas was used up about 6 billion years ago. The metallicity of the thick disk increased by more than a factor of ten.

The study found a correlation between the ages of the stars and the metallicity of the disk. That means that the gas that came with the GSE must have been turbulent, causing it to mix more thoroughly in the disk.

The GSE merger was recently discovered by Astronomers. It has shaped our understanding of the history of the Milky Way and it is getting clearer. The new study gives us a more detailed account.

Since the discovery of the ancient merger with Gaia-Sausage-Enceladus, we didn't have a clear picture of what the Milky Way looked like.

Our results provide details about the birthday, star formation rate and metal enrichment history of that part of the Milky Way. The picture of when and how our galaxy was formed is revolutionizing thanks to these discoveries.

Astronomers have discovered more about the universe. It is difficult to map its structure because we are in the middle. The best catalogue of the stars in the Milky Way has been provided by the Gaia mission. Each data release gets better.

With each new analysis and data release, Gaia allows us to piece together the history of our galaxy in even more detail. Astronomers will be able to enrich the story with even more details with the release of Gaia DR3 in June.

Analyzing the structure and history of the Milky Way is one of the benefits of the Gaia mission. It is difficult to observe the galaxies after two billion years. Powerful telescopes are required. A long-awaited space telescope is about to begin observations.

The James Webb Space Telescope has the power to look back in time. It will be able to see the Universe's earliest galaxies.

Astronomers want to know more about the merger and how it led to star formation and shaped our universe. The high-redshift galaxies similar to the Milky Way could help answer some questions.

The full third data release from Gaia will be released in June. There will be ages, metallicity, and spectrum for over 7 million stars in the DR3 catalogue. The combination of DR3 and the JWST will be potent.

As the Universe grows, what will it tell us? The Universe is expanding thanks to dark energy, but it is also being pulled apart by gravity. The galaxies tend to clump together. The Local Group includes The Milky Way.

The groups stay coherent because of the combined gravity, but they drift away from one another due to expansion. The larger the group, the smaller it becomes.

The GSE and globular clusters have been consumed by the Milky Way. The Large Magellanic Cloud is consuming the Small Magellanic Cloud.

In about 4.5 billion years, the Local Group will be merged with the larger, larger, and even larger, AndromedaGalaxy.

The future of the Milky Way might be easier to discern than its past. The evidence we seek keeps vanishing from us, lost to time and distance.

The JWST and the Gaia DR3 have the potential to change the course of the Universe. They can shed more light on the history of the Milky Way. Hopefully, we will end up with a more thorough historical timeline.

The article was published by Universe Today. The original article is worth a read.