A Meteor of Apparent Interstellar Origin in the CNEOS Fireball CatalogOPEN ACCESS (16 April 2019 draft was updated on 19 April 2022, publ. 2 November 2022)
Amir Siraj, Abraham Loeb
Update (2 November 2022):
The Astrophysical Journal, Volume 939, Number 1
Published: 2 November 2022
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“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).”
Updated draft version: 19 April 2022, submitted to ApJL
“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 ∼ 0.45m meteor detected at 2014-01-08 17:05:34 UTC as originating from an unbound hyperbolic orbit with 99.999% confidence. The U.S. Department of Defense has since verified that “the velocity estimate reported to NASA is sufficiently accurate to indicate an interstellar trajectory.” We infer that the meteor had an asymptotic speed of v∞ ∼ 42.1 ± 5.5 km s−1 outside of the solar system. Its origin is approximately towards R.A. 49.4 ± 4.1◦ and declination 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). Its high LSR speed implies a possible origin from the deep interior of a planetary system or a star in the thick disk of the Milky Way galaxy. The local number density of its population is 106+0.75/−1.5 AU−3 or 9 × 1021+0.75/−1.5 pc−3 (necessitating 0.2 – 20 Earth masses of material to be ejected per local star). We show that the detections of CNEOS 2014-01-08, ‘Oumuamua, and Borisov collectively imply that the differential size distribution in good agreement with a collisional distribution, with a power-law slope is q ∼ 3.6 ± 0.5, where the quoted uncertainty corresponds to 2σ. We then consider the possibility of analyzing interstellar meteor compositions based on spectroscopy of their gaseous debris as they burn up in the Earth’s atmosphere. We propose a strategy for determining the orbits and chemical compositions of interstellar meteors, using a network of ∼ 600 all-sky camera systems to track and conduct remote spectroscopy on meteors larger than ∼ 5cm once every few years. It should also be possible to retrieve meteorites from the impact sites, providing the first samples of materials from other planetary systems.”
Original draft first published on 16 April 2019, see also LINK
