Scientists estimate the number of interstellar objects visiting the solar system

(ORDO NEWS) — Simulations have shown that several interstellar asteroids fly through the solar system every year, and one interstellar comet – every 10-20 years.

In recent years, astronomers have brought several finds that have never happened before, including a couple of interstellar objects that were noticed during their flight through the solar system. In 2017, Oumuamua was discovered – apparently an interstellar asteroid, although Harvard professor Avi Loeb believes it could also be an artificial probe. And in 2019, the Crimean astronomer Gennady Borisov noticed an interstellar comet, which later received his name.

Observing such small objects moving rapidly along extremely unusual trajectories remains extremely difficult. Nevertheless, it is clear that guests from other stars visit the solar system every now and then. How often this happens was asked by a team of scientists led by Marshall Eubanks of the nonprofit Initiative for Interstellar Studies (i4is). Their article is being prepared for publication in The Astronomical Journal and has already been submitted to the open online preprint library

To do this, the authors turned to the concept of a local rest standard (LSP) – a conditional point that defines the origin of coordinates in the vicinity of the star. In space, where there are no fixed directions and landmarks to which the coordinate axes could be “rigidly” tied, astronomers use the LSP, which is determined by the movement of the Sun and the environment. Similar LSPs can be found for other stars from which interstellar bodies fly to us. Moving through the solar system, they must maintain the relative speed given by the LSP in their parent system.

Using data on the speeds of stars, which were collected as part of the Gaia astrometric mission, scientists have calculated that up to seven interstellar asteroids like Oumuamua can fly through the solar system every year. Moreover, the speed of such objects should be very high, reaching 40 kilometers per second or more. So even Oumuamua, with its 26 kilometers per second, moved relatively slowly. Interstellar comets like 2I / Borisov should appear less frequently, about once every 10-20 years.

According to the estimates of Oybanks and his co-authors, the vast majority of interstellar asteroids arrive to us from the limits of the galactic disk, but about three times in a century free-flying objects can appear, arriving from outside the borders of the Milky Way.


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