First Measurement of Rare Saturn-Sized Rogue Planet’s Mass

Artist's impression of a rogue planet

Artist’s impression of a rogue planet capturing light from a distant source

Credit: J. Skowron/OGLE

Located nearly 10,000 light-years away, a Saturn-sized planet roams through the vacuum of space. This enigmatic rogue planet was discovered through the joint efforts of ground-based telescopes and the Gaia Space Telescope, marking the first time researchers have measured the mass of a free-floating exoplanet.

Typically, rogue planets found are either more massive than Jupiter or lighter than Neptune, creating a gap known as the “Einstein Desert.” This gap is attributed to the fact that lighter celestial bodies are more likely to be ejected from their stellar orbits, while heavier planets may form independently in open space, similar to stars.

This newly identified exoplanet is extremely rare and has been assigned two designations: KMT-2024-BLG-0792 and OGLE-2024-BLG-0516. Andrzej Udalski, along with researchers from the University of Warsaw, made this groundbreaking discovery using distinct ground-based telescopes. What makes it even more remarkable is its measured mass, which is approximately one-fifth that of Jupiter.

“What’s fascinating about this find is that it’s the first rogue planet we’ve measured in terms of mass, achievable through both Earth-based and Gaia observations,” says Gavin Coleman from Queen Mary University of London. The planet was detected via a method known as gravitational microlensing, occurring when light from a distant source is bent by the planet’s gravitational field, resulting in a halo effect around it. The alignment of the Gaia Space Telescope at the right moment allowed additional capture of this microlensing event.

“Mass is a crucial factor for classifying celestial bodies as planets,” Udalsky explains, confirming this as the first verified rogue planet. “This is a pivotal moment for recognizing that floating planets do indeed exist,” he added. The upcoming NASA Nancy Grace Roman Space Telescope, expected to launch in 2027, is anticipated to uncover even more such celestial discoveries.

“These planets should be quite numerous, with many being expelled from their original stellar systems during their formation’s early stages, providing key insights into how planetary systems develop,” Udalsky notes. This knowledge may contribute to understanding the formation of our own solar system, which some studies suggest may have inadvertently ejected planets in its early history.

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Source: www.newscientist.com

Saturn-Sized Planets Can Orbit the Closest Sun-Like Star

What might the artistic concept of a gas giant in orbit around Alpha Centauri A resemble?

ESA/Webb Copyright: NASA, ESA, CSA, STSCI, R.

A massive planet comparable to Saturn is potentially identified orbiting a sun-like star in our nearest stellar system, Alpha Centauri.

Located just four light-years from Earth, Alpha Centauri is the closest star system to us, comprising three stars: Alpha Centauri A, Alpha Centauri B, and the Red Dwarf Star Proxima Centauri. Scientists have long speculated that planets akin to those in our solar system could exist in such systems, and whether planets can reside at distances similar to our Sun’s “habitable zone” around binary stars has been a matter of intrigue. “These stars are very bright, relatively close, and move quickly across the sky,” mentions Charles Baichman from Caltech in a statement.

Recent observations gathered by the James Webb Space Telescope (JWST) mid-infrared instrument suggest that a gas giant possibly as substantial as Saturn is orbiting the sun-like star, Alpha Centauri A. This discovery has come as a surprise. “Webb was specifically designed to identify the most distant galaxies, not exoplanets,” remarked Beichman, underscoring that such an identification must be meticulously coordinated through numerous observations, evaluations, and computer simulations, which “can yield remarkable insights.”

While previous methodologies for detecting planets relied on indirect measurements, the JWST executed a “more ambitious” approach by actually gathering light from potential planets, according to Alan Boss of Carnegie Science in Washington, DC, who was not involved in this particular study. Nevertheless, visibility of the potential planets was lost in subsequent observations.

“We’re encountering a case of a disappearing planet!” exclaimed Aniket Sanghi, also at Caltech, in a statement. The research team ran simulations of millions of possible trajectories to solve this conundrum, determining that “in half of the possible simulated orbits, the planet would have been too close to the star, making it undetectable by Webb in both February and April 2025,” he said.

As a gas giant, this planet wouldn’t support life as we know it. However, if this finding is validated, it could significantly enhance our understanding of planet formation around stars. “The mere existence of two closely situated stars within a stellar system will challenge our comprehension of how planets form, survive, and evolve under such chaotic circumstances,” Sangi pointed out. “This is also crucial for Earth, as it is our closest neighbor, beside the giant planets in our solar system, with a temperature and age somewhat akin to Earth.”

This revelation has been documented in two accepted papers for publication in Astrophysics Letters.

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Source: www.newscientist.com