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ApJ · 4 DAYS AGO
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Solving the Mystery of Twin Light Patterns from Spinning Dead Stars

By Space.Fan Editorial Desk

Scientists have uncovered a mathematical glitch that explains why researchers often get two different answers when studying neutron star hot spots.

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The Drop

s are the super dense remains of giant s that have run out of fuel. They spin very fast, and astronomers use special telescopes like NICER to track hot spots on their surfaces that glow with X-rays. By studying how these spots flicker as the rotates, scientists can figure out how big and heavy the is. This information helps us learn what happens to matter when it gets squashed down into an incredibly small space. Researchers usually use computer models to turn these flickers into a map of the . However, they sometimes find that the math gives them two different possible answers for the same . This is called a degeneracy, which is like a math puzzle where two different ting numbers both lead to the exact same result. Researchers Tong Zhao, Mingyu Ge, and Renxin Xu decided to look closer at these models. They found that in simpler versions of their math, the model naturally produces two matching answers for the same data. By creating digital versions of signals, they showed that even when you add in realistic effects like how the moves and how instruments take measurements, this confusion still hides inside the calculations. This explains why previous studies might have hit a wall when trying to pick between two different, equally likely shapes for the hot spots on a .
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Why It Matters

Understanding these hot spots is essential for measuring the size and weight of s. If our math models are giving us two different answers at the same time, we cannot be sure which one is the truth. This study helps scientists realize that the double-answer problem might be a built-in feature of the math rather than a mistake in the data. By recognizing this pattern, researchers can now build better, more reliable models to study the most dense objects in the universe.
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The Catch

While this study explains why some math models get confused, it focused on a simplified version of a 's surface. In reality, s may have much more complex shapes for their hot spots, and they have background noise from space that could change how these answers look. Scientists still need to do more work to see if this same problem stays just as strong when they use more complicated, real-world data.

Put That in Perspective

Measuring neutron stars is the best way we have to test how matter behaves under extreme pressure. This new research provides a foundation for upcoming space missions, like the eXTP mission, to make more accurate observations of these spinning stars starting in the next few years.

Source September 24, 2026
Tong Zhao, Mingyu Ge, Renxin Xu
Peking University, Institute of High Energy Physics·The Astrophysical Journal·10.3847/1538-4357/ae99d0

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