A novel approach in astronomy may significantly enhance the ability to identify Earth-like exoplanets. By applying a technique borrowed from radio astronomy, astronomers are considering treating optical telescopes as arrays composed of smaller telescopes. This innovative method could lead to clearer observations of distant planets.
In radio astronomy, the large wavelengths involved present challenges for capturing high-resolution images using a single dish. To overcome this, researchers utilize an array of antennas that collectively gather signals. The precise timing of these signals enables astronomers to employ a technique called interferometry. This involves correlating the times at which light from a distant radio source reaches each antenna, effectively transforming the array into a virtual antenna disk the size of the entire setup.
Unlike radio wavelengths, visible light operates on an atomic scale, allowing even moderately sized telescopes to produce excellent images. For instance, the primary mirror of the Hubble Space Telescope has a diameter of just 2.4 meters. However, advancements in optical astronomy are prompting a shift in methodology. Modern telescopes, including the James Webb Space Telescope, now utilize multiple hexagonal mirrors instead of relying solely on a large primary mirror. These mirrors can be focused onto a single detector, eliminating the need for interferometry in many cases.
A recent study has proposed a technique called Kernel Phase Interferometry (KPI). This method, while distinct from traditional radio interferometry, shares several advantages. In standard interferometry, individual signals combine to form a singular image. In contrast, KPI begins with a single image and creates a virtual array of signals through Fourier transformations. This virtual array can then be used to generate an image via correlation, akin to the process used in radio signal analysis.
Typically, employing this method might not yield significant benefits, as radio interferometry can produce high-resolution images that may simply introduce artifacts based on the antenna layout. However, one of the strengths of interferometry is its ability to isolate sources effectively. The authors of the study illustrate that using KPI on observations, such as those of close binary stars, allows for better differentiation of individual sources.
This technique holds particular promise for observing Earth-sized planets that orbit Sun-like stars closely. The advantage of KPI is that it does not require new observations; instead, it can analyze existing data from telescopes like JWST to produce direct images of exoplanets and closely situated binary stars. Essentially, from a single observation, multiple insights can be derived through this innovative approach.
The study, led by Chelsea Adelman and colleagues, highlights the potential of KPI in the ongoing quest to discover and understand exoplanets, particularly those similar to Earth.
Reference: Adelman, Chelsea, et al. “First demonstration of kernel phase interferometry on JWST/MIRI: prospects for future planet searches around post main sequence stars.” Techniques and Instrumentation for Detection of Exoplanets XII. Vol. 13627. SPIE, 2025.
