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Astronomers are questioning established planet formation theories after discovering an exoplanet that defies expectations. This Neptune-sized planet, named LHS 3154b, orbits a star known as LHS 3154, which is much smaller and cooler than our sun. Despite its small mass, LHS 3154 hosts a massive planet with an orbital period of 3.7 Earth days. This discovery, detailed in a new study published in Science, challenges existing notions of planetary formation.
Astronomy professor Suvrath Mahadevan expressed, “This discovery really drives home the point of just how little we know about the universe… We wouldn’t expect a planet this heavy around such a low-mass star to exist.”
Our understanding of planet formation suggests that a star’s mass determines the amount of material present within their planetary disks, which in turn influences the mass of the planets forming around them. However, the discovery of LHS 3154b contradicts these expectations, shaking the foundation of our knowledge about planets and stars.
The habitable zone
LHS 3154b orbits a star 51 light-years away from the sun and was detected using the Habitable Zone Planet Finder, HPF, at the McDonald Observatory in Texas. This discovery challenges traditional notions of habitable zones by showing that planets closely orbiting low-mass stars can still maintain elements essential for life.
The research team behind HPF, led by Suvrath Mahadevan, designed the instrument to detect planets within the habitable zone of small, cool stars where liquid water could exist. The HPF’s detection of this unusual exoplanet raises questions about existing planet formation theories.
A planetary puzzle
The planet’s heavy core indicates that there was likely more solid material in the planet-forming disk than initially present around LHS 3154. This challenges our theories of planet formation and promises to reveal new insights into the most common stars in our galaxy and how they form planets.
This rare discovery is an extreme test case for all existing planet formation theories and demonstrates the potential for groundbreaking discoveries about planets and stars.
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