Scientists just caught a space collision involving an 'impossible' object that's lighter than the Sun.
March 19, 2026
Original Paper
Search For a Counterpart to the Subsolar Mass Gravitational Wave Candidate S251112cm
arXiv · 2603.17009
The Takeaway
Standard physics says black holes and neutron stars must be significantly heavier than our Sun to form, yet a new gravitational wave signal comes from an object that is 100% likely to be 'sub-solar' in mass. This find forces astronomers to look for speculative new models of how such small, dense objects could exist.
From the abstract
The recent gravitational-wave (GW) alert from a compact object merger involving at least one subsolar mass (SSM) object has prompted questions about their origins. S251112cm is reported by LIGO/Virgo with a false alarm rate of 1 per 6.2 years, nearby luminosity distance $93 \pm 27$ Mpc, probability of containing a SSM object of 100%, and probability of containing a $1-3~M_\odot$ object of just 8%. Such a system likely did not involve the supersolar neutron stars or black holes invoked to explain