A Meteor of Apparent Interstellar Origin in the CNEOS Fireball Catalog

• Published in: The Astrophysical journal 2022-11, Vol.939 (1), p.53
• Main Authors: Siraj, Amir, Loeb, Abraham
• Format: Article
• Language: English
• Subjects: Abundance; Astrophysics; Calibration; Fireballs; Interstellar objects; Interstellar space; Meteors; Solar system; Velocity; Velocity estimation
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac8eac

The earliest confirmed interstellar object, ‘Oumuamua, was discovered in the solar system by Pan-STARRS in 2017, allowing for a calibration of the abundance of interstellar objects of its size ∼100 m. This was followed by the discovery of Borisov, which allowed for a similar calibration of its size ∼0.4–1 km. One would expect a much higher abundance of significantly smaller interstellar objects, with some of them colliding with Earth frequently enough to be noticeable. Based on the CNEOS catalog of bolide events, we identify the ∼0.45 m meteor detected at 2014 January 8 17:05:34 UTC as originating from an unbound hyperbolic orbit. The U.S. Department of Defense has released an official letter stating that “the velocity estimate reported to NASA is sufficiently accurate to indicate an interstellar trajectory,” which we rely on here as confirmation of the object’s interstellar trajectory. Based on the data provided by CNEOS, we infer that the meteor had an asymptotic speed of v ∞ ∼ 42.1 ± 5.5 km s −1 outside of the solar system. Note that v ∞ here refers to the velocity of the meteor outside the solar system, not the velocity of the meteor outside the atmosphere. Its origin is approximately toward R.A. 49.°4 ± 4.°1 and decl. 11.°2 ± 1.°8, implying that its initial velocity vector was 58 ± 6 km s −1 away from the velocity of the local standard of rest (LSR).