Revolutionary Discovery: Giant Exoplanet Challenges Planet Formation Theories
Astronomers have made a groundbreaking discovery - a colossal exoplanet orbiting a diminutive, cool star This finding challenges conventional planet formation theories, leaving scientists puzzled by its existence
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Astronomers are baffled by the discovery of an exoplanet that challenges existing theories of planet formation.
A new study published in the journal Science has identified a planet, named LHS 3154b, that orbits an ultracool M-dwarf star called LHS 3154. This planet is about the mass of Neptune and over 13 times more massive than Earth, and it completes one orbit around the star every 3.7 Earth days. This makes it the most massive known planet in a close orbit around one of the coldest, low-mass stars in the universe. The discovery is causing scientists to rethink their understanding of planetary system formation.
This graphic compares the sizes of our sun and Earth with the smaller, cooler LHS 3154 star and its orbiting planet, LHS 3154b.
According to a statement from study coauthor Suvrath Mahadevan, who is the Verne M. Willaman professor of astronomy and astrophysics at Penn State, "This finding emphasizes how little we truly understand about the universe. It is unexpected to find a planet of this size orbiting a star with such low mass."
Large clouds of gas and dust are the birthplace of stars, leaving behind a disk that gives rise to planets. The material within these disks dictates the size of the planets that form around the stars. This material is influenced by the star's mass, with small M dwarf stars in the Milky Way galaxy often having rocky planets orbiting them instead of gas giants.
around LHS 3154, a low-mass star, is not anticipated to contain sufficient solid mass to create a planet," Mahadevan stated. "Nevertheless, a planet exists, thus prompting a reevaluation of our comprehension of planetary and stellar formation."
The planet was found to be orbiting a star located approximately 51 light-years away from our sun. This discovery was made possible by the Habitable Zone Planet Finder (HPF) instrument, which is mounted on the Hobby-Eberly Telescope at the McDonald Observatory in Texas.
By tracing the connection between two neighboring planets at regular intervals along their orbits, a distinct pattern is formed for each pair. The six planets in the HD110067 system collectively form a captivating geometric pattern as a result of their resonance-chain.
A nearby six-planet solar system with an optimal configuration has been found by astronomers.
Led by Mahadevan, a team of scientists developed the HPF to identify planets that orbit within the habitable zone of small, cool stars. This zone is the ideal distance from a star for a planet to have the necessary warmth to sustain liquid water on its surface and potentially harbor life.
The cooler temperature of small stars allows planets to orbit them at closer distances while still maintaining elements like water on their surfaces. This close orbit creates a gravitational wobble that the HPF can detect in infrared light.
An analogy can be made to a campfire, according to Mahadevan. As the campfire cools down, you need to get closer to stay warm. Similarly, if the star is cooler, a planet needs to be closer to maintain the right temperature for liquid water. This close orbit can be detected by subtle changes in the star's light as it is tugged on by the orbiting planet.
The research team suggests that the planet has a dense core, indicating that there must have been a greater amount of solid material in the planet-forming disk than was originally thought to be present near the star. This finding is based on modeling and analysis, as explained by study coauthor Megan Delamer, an astronomy graduate student at Penn State.
This image depicts the HH 1177 system, situated in the Large Magellanic Cloud, a nearby galaxy to our own. The central glowing star, young and massive, is attracting material from a dusty disc while also releasing material in powerful jets. Using the Atacama Large Millimeter/submillimeter Array (ALMA), of which ESO is a partner, a team of astronomers identified evidence of the presence of this disc by observing its rotation. This marks the first instance of a disc around a young star â the same type of disc that forms planets in our own galaxy â being discovered in another galaxy.
M. Kornmesser/ESO
Planet-forming disk spotted around star in another galaxy for the first time
The researchers believe that there must be at least 10 times more dust in the disk than is typically found in disks around low-mass stars.
"We are finding it challenging to reconcile our current theories of planet formation with what we are observing," stated Delamer. "Based on our survey work with the HPF and other instruments, it seems that an object like the one we discovered is probably very rare, so detecting it has been incredibly thrilling."
Several large planets have been discovered orbiting smaller stars, including GJ 3512 b which was found in 2019. However, their orbital periods are significantly longer and they do not orbit their stars as closely.
Mahadevan stated, "What we have found presents a rigorous challenge for all current planet formation theories. This is precisely why we created HPF, to uncover how planets form around the most prevalent stars in our galaxy and to locate those planets."
