Astronomers using 'light-fingerprints' to uncover the mysteries of exoplanets

Scientists create 'reference catalogue' using calibrated spectra

Astronomers at Cornell University are now using "light-fingerprints" to uncover the mysteries of exoplanets.

The researchers said in a new study that using this technique, they've managed to create a reference catalogue using calibrated spectra and geometric albedos (the light reflected by a surface) of 19 of the most diverse bodies in our solar system.

This includes all eight planets, from rocky to gaseous, nine moons, from frozen to lava spewing, and two dwarf planets (one in the asteroid belt called Ceres, and one in the Kuiper belt, Pluto).

By comparing observed spectra and albedos of exoplanets to this catalogue of the home planetary system, the scientists said they will be able to characterise them in reference to the wide range of icy, rocky and gaseous worlds in our home system.

"We use our own solar system, and all we know about its incredible diversity of fascinating worlds, as our Rosetta Stone," said the study's co-author Lisa Kaltenegger, who is the associate professor of astronomy and director of the Carl Sagan Institute.

"With this catalogue of light-fingerprints, we will be able to compare new observations of exoplanets to objects in our own solar system, including the gaseous worlds of Jupiter and Saturn, the icy worlds of Europa, the volcanic world of Io and our own life-filled planet."

The catalogue will enable scientists to prioritise time-intensive, high-resolution observations of extrasolar planets and moons as well as offer insights into what kind of worlds won't be so easy to categorise without high-resolution spectra.

The catalogue is free to access on the Carl Sagan Institute website, and includes high- and low-resolution versions of the data, which shows astronomers the influence of spectral resolution on an object's identification. It also offers examples of how the colours of the 19 solar system models would change if they were orbiting stars other than our sun.

"The technology to directly collect the light from Earth-sized planets around other stars is currently in a clean room waiting to be assembled and trained on the right target," added Jack Madden, a doctoral candidate at the Carl Sagan Institute and lead author of the study.

"With the upcoming launch of the James Webb Space Telescope and the current construction of large ground-based telescopes, such as the Giant Magellan Telescope and the Extremely Large Telescope, we are entering a new age of observational ability.

"So we need a reference catalogue of all the planets and moons we already know, to compare these new exoplanet spectra to," said Madden.