Interstellar Meteors Are Outliers in Material Strength

The first interstellar meteor larger than dust was detected by US government sensors in 2014, identified as an interstellar object candidate in 2019, and confirmed by the Department of Defense in 2022. Here, we describe an additional interstellar object candidate in the CNEOS fireball catalog and compare the implied material strength of the two objects, referred to here as IM1 and IM2, respectively. IM1 and IM2 are ranked first and third in terms of material strength out of all 273 fireballs in the CNEOS catalog. Fitting a log-normal distribution to material strengths of objects in the CNEOS catalog, IM1 and IM2 are outliers at the levels of 3.5 sigma and 2.6 sigma, respectively. The random sampling and Gaussian probabilities, respectively, of picking two objects with such high material strength from the CNEOS catalog are similar to 10(-4) and similar to 10(-6). If IM2 is confirmed, this implies that interstellar meteors come from a population with material strength characteristically higher than meteors originating from within the solar system. Additionally, we find that if the two objects are representative of a background population on random trajectories, their combined detections imply that similar to 40% of all refractory elements are locked in meter-scale interstellar objects. Such a high abundance seemingly defies a planetary system origin.

Automated summary

The first interstellar meteor larger than dust was detected in 2014 and confirmed by the Department of Defense in 2022. An additional interstellar object candidate, IM2, with high material strength was found. If IM2 is confirmed, it implies that interstellar meteors have higher material strength compared to those originating from within the solar system.