This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: It's nearly 170 million years old. It's more than 2.5 times the size of Earth.
And it's the first exoplanet discovered and cataloged by researchers with the Wisconsin Center for Origins Research (WiCOR). Max Kroft, a graduate student in the lab of Assistant Professor of Astronomy Thomas Beatty, is the lead author on a paper that characterizes GJ 523b, a dense exoplanet classified as a "Mega-Earth" because of its massive size. The paper is under review and is available through the preprint server arXiv.
"People have been using the phrase 'Mega-Earth' for more than a decade, but we've never had a planet that let us say concretely what one is," says Beatty. What is also striking is that nailing down the definition of a Mega-Earth isn't something we astronomers can really do by ourselves: We need geologists who understand how iron and rock behave at pressures no laboratory on Earth can reach, and atmospheric scientists who can tell us how much of what we measured is rock at all." WiCOR launched in 2024 as a collaboration of researchers from what are now seven UW–Madison departments (astronomy, biology, chemistry, geoscience, atmospheric and oceanic sciences, physics and bacteriology) pursuing projects related to the origins of life in the universe. As part of those efforts, WiCOR researchers have been on the lookout for Hycean exoplanets, a theorized type of exoplanet outside our solar system with a large ocean and temperate atmosphere that could potentially support life.
Planetary candidates have been identified by the Transiting Exoplanet Survey Satellite (TESS), a NASA satellite mission launched in 2018. TESS's main objective is to monitor stars to see if their brightness dips, a possible indication of an exoplanet. "There's this periodic dipping of the star's light.
We think that's a planet passing in front of the star and transiting. It's blocking some of the light from the star, and the star gets dimmer," says Kroft. TESS has identified more than 8,000 candidate planets, but less than a quarter of them have been confirmed.
Kroft used a ground-based telescope in Arizona, WIYN, with a high-resolution spectrograph to follow up on the candidate that eventually became GJ 523b. "We picked out this planet based on what we thought its size and temperature were," explains Kroft. "A bigger planet makes a bigger dip, so we get an idea of the size, and based on how often that dip happens, we get the distance of its orbit, and we can use that to estimate the temperature of the exoplanet." Using the spectrograph and data collected by the James Webb Space Telescope, Kroft and the rest of the WiCOR team were able to determine information about GJ 523b's density and atmosphere.
Extract — continue reading at the source.
