How to distinguish the impact crater of an interstellar object

Aug. 12 () –

Yale University astrophysicists have investigated how to identify impact craters that may have been created by interstellar objects.

Examination of these objects has gained notable interest throughout the scientific community since the discoveries and subsequent investigation of ‘Oumuamua and Comet 2I/Borisov in 2017 and 2019, respectively.

In his article, submitted to Earth and Planetary Astrophysics and available on arXivthe Yale researchers discussed how impact melt volume within fixed-diameter craters might be a possible pathway to recognize craters produced by an interstellar object, since higher-velocity impacts produce larger impact melt volumes.

“`Oumuamua and Borisov were historical discoveries”, said Samuel Cabot, a doctoral candidate in the Department of Astronomy at Yale University. “They have generated considerable response in the astrophysics community. At present, there is no theory that adequately explains all aspects of `Oumuamua. The strongest arguments to date point to an entirely new type of astronomical object, beyond the asteroids and comets with which we are familiar Comet Borisov was also peculiar in that its composition was different from virtually all comets in our own Solar System. The fact that it was ejected from its original system conveys some information about the early stages of planet formation.”

For their study, the researchers performed hydrodynamic simulations with projectiles of different masses and impact speeds of up to 100 km. per second. The researchers chose a maximum speed of 100 km. per second, since it is currently hypothesized that impacts within our solar system never reach a speed equal to or greater than this, so these speeds are rarely used in the scientific literature.

While the paper discusses how cratering with impact melt volume to diameter ratios could be used to identify craters produced by an interstellar object, it concludes that their location may soon be possible through in situ analysis (original location ) or return of samples from robotic and manned missions.

The study focused specifically on impacts from the Moon, since the “distinguishing feature of interstellar objects is their relatively high encounter speed compared to asteroids and comets“, states the document.

“The most promising indicators of an interstellar impact involve chemical analysis of the material in and around the crater,” explains Cabot. “The Artemis missions may be crucial here, as they will offer some of the first opportunities to analyze soil and rock on the Moon since the Apollo program. Right now, however, it’s hard to pinpoint a specific crater.”