New Telescope Design Could Sharply Improve Exomoon Detection

The search for exomoons – moons orbiting planets outside our solar system – is a challenging but potentially rewarding endeavor. These celestial bodies could offer valuable insights into planet formation, the history of planetary migration, and even the possibility of habitable environments beyond Earth. That said, the reality is a bit more complicated. detecting these relatively small objects at vast distances requires innovative observational techniques. A new study proposes a novel approach: building an interferometer with significantly longer baselines than existing instruments.

Interferometry, in essence, combines the light collected by multiple telescopes to create a virtual telescope with a much larger aperture. This increased aperture translates to higher resolution, allowing astronomers to discern finer details and detect fainter objects. The Very Large Telescope Interferometer (VLTI), for example, links several telescopes at the European Southern Observatory (ESO) in Chile. That said, the reality is a bit more complicated. the new study suggests that an interferometer with baselines extending kilometers – far beyond the VLTI's current capabilities – could dramatically improve exomoon detection.

The core of the proposed method relies on astrometry, the precise measurement of the positions and motions of stars and other celestial objects. As a planet orbits a star, the star itself exhibits a slight wobble due to the planet's gravitational pull. Similarly, if a planet has a moon, the planet will also wobble slightly as it orbits the common center of mass. This wobble, though minuscule, can be detected through extremely precise astrometric measurements. The study suggests that an interferometer capable of achieving an astrometric precision of 1 microarcsecond (μas) would be able to detect Earth-mass and even sub-Earth-mass exomoons orbiting Jupiter-like planets at distances of 50 to 200 parsecs from Earth. A parsec is a unit of distance commonly used in astronomy, equivalent to about 3.26 light-years. Therefore, this new technology could potentially find exomoons hundreds of light years away.

This proposed instrument wouldn't directly image the exomoons. Instead, it would infer their existence from the subtle wobble they induce in their host planets. This method is particularly effective for detecting moons orbiting large planets, as their greater gravitational influence makes the wobble more pronounced. The target planets are Jupiter-like because larger planets exert a greater gravitational influence on their moons, making the 'wobble' more pronounced and easier to detect. Detecting smaller, Earth-sized planets and their moons presents a significantly greater challenge.

The ability to detect Earth-mass and sub-Earth-mass exomoons is particularly exciting because it opens up the possibility of finding potentially habitable environments. While Jupiter-like planets themselves are unlikely to harbor life, their moons could, under certain circumstances, possess liquid water and other conditions conducive to life. Europa, one of Jupiter's moons in our own solar system, is a prime example of a moon with a subsurface ocean that could potentially support life. Learning more about the search for habitable zones is therefore highly relevant.

While the study presents a promising avenue for exomoon detection, it's essential to acknowledge the limitations. Building and operating a kilometric baseline interferometer would be a technologically complex and expensive undertaking. Furthermore, even with such an instrument, detecting exomoons will remain a challenging task, requiring extremely precise measurements and sophisticated data analysis. Another important factor is the dynamic stability of the exomoon's orbit. The study focuses on exomoons in dynamically stable orbits, meaning that their orbits are not disrupted by gravitational interactions with other planets or stars in the system. That said, the reality is a bit more complicated. many exoplanetary systems are dynamically complex, and it's not always clear whether a moon can maintain a stable orbit for extended periods.

Despite these challenges, the prospect of detecting exomoons and exploring their potential for habitability makes the development of new observational techniques a worthwhile pursuit. An interferometer with kilometer-long baselines could represent a significant step forward in our search for these elusive objects, potentially revolutionizing our understanding of planetary systems and the distribution of potentially habitable environments in the universe. Understanding the broader field of exoplanet exploration provides context for these advancements.

Editor’s note: This article was independently written by the Scoopliner Editorial Team using publicly available information.