Original title: Probing Dark matter-Baryon Interaction with S301--the Fastest Known Star in the Milky Way
Yugen Lin · September 2026
Dark matter is invisible stuff that makes up most mass in space, but scientists still struggle to detect how it interacts with normal matter. To study this, researchers looked at S301, the fastest known star in our galaxy. S301 travels on an oval path around Sgr A*, the giant black hole at the galactic center. At its closest point, it gets around 12 AU away while moving at about 25000 km/s. The researchers calculated how much energy dark matter particles colliding with protons would dump into the star. They found that even within known limits from Earth tests and astronomy, these collisions can deposit enough energy to change the star's brightness and how it ages over time.
Imagine you are trying to catch a ball in a dark room. You can't see it, but you know it's there because you hear it bounce. The harder part is that the ball is moving extremely fast and only comes close to you for a split second. In this paper, the star S301 is like that ball, and the dark matter is the invisible room. The star's close pass to the galactic center is like the ball coming near you, and any interaction with dark matter would be like the ball hitting something you can't see, leaving a trace in the star's energy.
Dark matter makes up most of the universe's mass, but we barely know how it interacts with ordinary matter. This study shows that a single star, S301, can act as a natural detector by measuring how dark matter collisions heat it up. If the star's brightness changes in unexpected ways, it could reveal properties of dark matter that lab experiments miss.
The study is theoretical and does not confirm actual dark matter interactions. It assumes a specific dark matter density distribution at the Galactic center. The predicted luminosity changes must be disentangled from other astrophysical effects. Observational confirmation would require long-term monitoring of S301.
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Probing Dark matter-Baryon Interaction with S301--the Fastest Known Star in the Milky Way — Yugen Lin
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.