Roberto Gorelli points our attention at two recently published meteor related papers.

Discovery of a Meteor of Interstellar Origin

This paper has been submitted for publication by Amir Siraj and Abraham Loeb.

Abstract: The first 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. One would expect a much higher abundance of 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 an asymptotic speed of v∞ ∼ 43.8 [+12.9,−31.2] km s^−1 outside of the solar system. Its origin is approximately towards R.A. 51.1° and declination +10.4°, implying that its initial velocity vector was 57 ± 24 km s^−1 (all error bars representing ±2σ) 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 10^6 AU^−3 or 9×10^21 pc^−3 (necessitating 0.2 – 20 Earth masses of material to be ejected per local star). This discovery enables a new method for studying the composition of interstellar objects, based on spectroscopy of their gaseous debris as they burn up in the Earth’s atmosphere.

You can download this paper for free: https://arxiv.org/pdf/1904.07224.pdf (4 pages).

 

Identifying Interstellar Objects Trapped in the Solar System through Their Orbital Parameters

This paper has been submitted for publication by Amir Siraj and Abraham Loeb.

Abstract: The first 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 and an estimation of the subset of objects trapped by the Jupiter-Sun system. Photographing or visiting these trapped objects would allow for learning about the conditions in other planetary systems, saving the need to send interstellar probes. Here, we explore the orbital properties of captured interstellar objects in the Solar System using dynamical simulations of the Jupiter-Sun system and initial conditions drawn from the distribution of relative velocities of stars in the Solar neighborhood. We compare the resulting
distributions of orbital elements to those of the most similar population of known asteroids, namely Centaurs, to search for a parameter space in which interstellar objects should dominate and therefore be identifiable solely by their orbits. We find that there should be thousands of ‘Oumuamua-size interstellar objects identifiable by Centaur-like orbits at high inclinations, assuming a number density  of ‘Oumuamua-size interstellar objects of ∼ 10^15 pc^−3 . We note eight known objects that may be of interstellar origin. Finally, we estimate that LSST will be able to detect several hundreds of these objects.

You can download this paper for free: https://arxiv.org/pdf/1811.09632.pdf (6 pages).