Interstellar Meteors Are Outliers in Material Strength

Abstract

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 3.5σ and 2.6σ, respectively. The random sampling and Gaussian probabilities, respectively, of picking two objects with such high material strength from the CNEOS catalog are ∼10−4 and ∼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 ∼40% of all refractory elements are locked in meter-scale interstellar objects. Such a high abundance seemingly defies a planetary system origin.

Chasing nomadic worlds: A new class of deep space missions

“…This approach was delineated in [132, Section 3.1] for 1I/'Oumuamua, and is generalizable to nomadic worlds. On specifying 𝑅 ∼ 1000 km from earlier, we obtain 𝐷 ISO ∼ 1.3 × 10 4 AU from (3) and 𝐻 ≈ 1.6 after setting  ∼ 0.1 in (12). We also select a relative speed of ∼ 100 km/s based on previous sections (i.e., broadly the terminal velocity of the spacecraft), and adopt a worst-case fiducial positional uncertainty of 𝜃 var ∼ 10 −5 rad, which is commensurate with 1I/'Oumuamua [255,256], an ISO with unusual nongravitational acceleration.…”

“…Furthermore, electric sails and magnetic sails each have a well-defined upper limit corresponding to the typical speed of the solar/stellar wind, i.e., around 400 km/s, as higher spacecraft speeds would lead to a net deceleration instead. 12 Reviews of the magnetic and electric sail concepts can be found in [202] and [203].…”

“…The field of ISOs was already quite active by the 1970s [2,3,4], but it has received a timely boost thanks to the recent discovery of the interstellar planetesimals 1I/'Oumuamua and 2I/Borisov in 2017 [5] and 2019 [6,7], respectively. Aside from this duo, interstellar dust grains and meteors have been analyzed, and their abundances constrained [8,9,10,11,12]; note, however, that their sizes are many orders of magnitude smaller than the class of objects tackled hereafter. These two interstellar interlopers have substantially enhanced our knowledge of ISOs [13,14,15,16], such as the size distribution and number density of interstellar planetesimals, while raising new questions in their wake.…”

Interstellar Objects from Broken Dyson Spheres

“…Below I demonstrate that if Dyson spheres existed to serve their civilizations for a limited time, most of them would have disintegrated within billions of years in the absence of extensive maintenance. In that case, their ejected fragments could appear as interstellar objects (Siraj & Loeb 2022a).…”