Mapping the Milky Way With Pulsing Stars

By Space.Fan Editorial DeskOctober 1, 2026 at 5:03 PM UTC

A new map of 6,240 pulsing stars helps reveal the messy, violent history of our home galaxy.

The Drop

Astronomers have created a huge new map of s known as RR Lyrae. These s are special because they pulse, growing brighter and dimmer on a regular schedule. By using a powerful tool called the Dark Energy Spectroscopic Instrument, or DESI, researchers tracked over 6,000 of these s located far out in the edges of the Milky Way. This is the first time scientists have gathered such a large collection of these pulsing s with this level of detail. To see these s clearly, the team developed a new math trick to figure out how each moves and how hot it is, even though they only took snapshots of each at different times. By looking at how these s shine and move, the team could tell where they came from. Some of these s are moving in very straight, stretched-out paths. Others are moving in more circular orbits. This helps scientists group the s by their family history. The team found that many of these s likely came from smaller galaxies that crashed into our own Milky Way long ago. One specific group of s matches perfectly with the leftovers of a massive collision known as the Gaia-Sausage-Enceladus merger. This was a major event in our galaxy's past that helped build the shape we see today.

Why It Matters

Understanding these s is like finding fossils in the dirt. By studying the chemical makeup and paths of these s, scientists can piece together a timeline of how the Milky Way grew. It helps prove that our galaxy was built through several collisions with smaller groups of s. This research confirms that the Milky Way is not a static object, but a structure shaped by dramatic events over billions of years.

The Catch

While this catalog is very large, it is only a t. The researchers had to use a mathematical model to estimate the s' properties from single snapshots. This means there is still a small margin for error when compared to watching a single pulse over its entire cycle. Future studies will need to refine these measurements to ensure the models for every are perfect.

Put That in Perspective

Scientists have studied the halo of our galaxy for decades, but DESI allows us to see much further out than ever before. Reaching 120,000 light-years from the center of the galaxy provides a wide view of our galactic neighborhood. Researchers will likely use this data next to build even better maps of the 'dark' parts of our galaxy that we cannot see directly.

Source October 1, 2026

ApJ

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