Finnish researchers have discovered a new type of matter inside neutron stars

“A Finnish research group has found strong evidence for the presence of exotic quark matter inside the cores of the largest neutron stars in existence. The conclusion was reached by combining recent results from theoretical particle and nuclear physics to measurements of gravitational waves from neutron star collisions. ”

https://www.helsinki.fi/en/news/science-news/finnish-researchers-have-discovered-a-new-type-of-matter-inside-neutron-stars

See also HIP Blog (in Finnish): https://blog.hip.fi/kvarkkiainetta-nakopiirissa/