Exoasteroid

An exoasteroid, exo-asteroid or extrasolar asteroid, is an asteroid located outside the Solar System. While exoasteroids and exoasteroid belts were once considered hypothetical, recent scientific studies and thorough analyses have provided evidence for their existence.^[1]

Evidence

Scientists propose that the formation of exoasteroids often results from the fragmentation of exoplanets by gas giants. These exoasteroids are presumed to be the remnants of smaller celestial bodies that endured the demise of their parent exoplanet. Analogous processes are hypothesized to have occurred during the formation of our Solar System.^[2]^[3]

inner planets of our Solar System.^[3]

History

In December 1988, American

astrophysicists Benjamin Zuckerman and Eric Becklin detected a substantial circumstellar disc encircling the white dwarf star G 29-38, stemming from a near-infrared survey of 200 white dwarfs.^[4] Zuckerman and Becklin conducted further investigations on the white dwarf star, uncovering that the circumstellar disc emits notable radiation within the 2 to 5 micrometer range. This discovery suggests potential interactions between exoasteroids and radiant matter, possibly leading to their ejection into space.^[5] Subsequent observations in 2004 by the Spitzer Space Telescope revealed the presence of a dust cloud surrounding G 29-38. This phenomenon is believed to have originated from the disintegration of an exocomet or exoasteroid as it interacted with the white dwarf over time.^[6]

Spitzers observations further proved that exoasteroids could exist.

In May 2023, the James Webb Space Telescope provided images of Fomalhaut,^[7] a young star positioned 25 light-years (ly) away from Earth. Scientists analyzed these images and conducted simulations and tests on Fomalhaut's asteroid belt, proposing that it likely formed due to collisions involving larger celestial bodies.^[7]^{[clarification needed]}

Another notable star hosting an asteroid belt is the white dwarf star

mid-infrared light, indicative of the recent destruction of an exoasteroid, which led to the formation of a cloud of metallic dust partially obscuring WD 0145+234 from Earth's view.^[8]

Detection

Artist's concept of an exoasteroid being ripped apart by its star

In 2013, astronomers discovered fragmented remnants of an exoasteroid orbiting the star

liquid water

around the star at some point in its history. It is postulated that the asteroid met its demise due to interactions with its star, leading to its fragmentation and subsequent formation of an asteroid belt around the star.

Following this discovery, scientists used the Cosmic Origins Spectrograph aboard the Hubble Space Telescope to analyze the chemical composition of the asteroid; it showed the presence of magnesium, silicon, iron, and oxygen within the asteroid's water.^[9]

Proposed observational methods

Exoasteroids can be detected through various methodical processes. The

transit method is a common technique used to discover extrasolar objects as they pass in front of their host star, providing scientists with the opportunity to observe their shape. Spectroscopy can be used to identify distinctive characteristics of exoasteroids, and allows to detect surface features. Other techniques include remote sensing and data from past missions to minor planets

.