Halo Meteors

Abstract

The stellar halo contains some of the oldest stars in the Milky Way galaxy and in the universe. The detections of `Oumuamua, CNEOS 2014-01-08, and interstellar dust serve to calibrate the production rate of interstellar objects. We study the feasibility of a search for interstellar meteors with origins in the stellar halo. We find the mean heliocentric impact speed for halo meteors to be $\sim 270 \mathrm{\;km\;s^{-1}}$, and the standard deviation is $\sim 90 \mathrm{\;km\;s^{-1}}$, making the population kinematically distinct from all other meteors, which are an order-of-magnitude slower. We explore the expected abundance of halo meteors, finding that a network of all-sky cameras covering all land on Earth can take spectra and determine the orbits of a few hundred halo meteors larger than a few mm per year. The compositions of halo meteors would provide information on the characteristics of planetary system formation for the oldest stars. In addition, one could place tight constraints on baryonic dark matter objects of low masses.