Astronomers have discovered a massive exoplanet designated GJ 523b that weighs roughly 23 times the mass of Earth but remains remarkably compact and dense, defying traditional planetary formation models that suggest objects of this size should naturally sweep up massive gaseous envelopes.
A newly identified exoplanet has upended long-standing astronomical theories regarding how worlds grow and evolve. Designated as GJ 523b, the unusual planetary body possesses a mass approximately 23.5 times that of Earth while maintaining a radius only about 2.55 times larger than our home planet. According to reporting from Detik, this combination packs matter into a tight volume, yielding a density of roughly 126.82 grams per cubic inch.
Telescope Observations and System Characteristics
The discovery began when the object was initially flagged as a candidate by the Transiting Exoplanet Survey Satellite (TESS), a NASA instrument designed to catch periodic dips in stellar light as planets cross in front of their host stars. To pin down the planet’s physical dimensions and gravitational pull, researchers turned to ground-based instruments.
Scientists used the 3.5-meter WIYN telescope housed at the Kitt Peak National Observatory in Arizona. By utilizing the facility’s NEID spectrograph, the research team measured the gravitational wobble the planet exerts on its parent star. Those ground measurements, paired with the transit data from space, allowed astronomers to calculate the exact mass and radius.
The host system itself is remarkably young in cosmic terms. Researchers estimate the star system is approximately hampir 170 juta tahun, providing a narrow window for how the planet formed and evolved into its current state. The planet completes one orbit around its host star every 17.75 days.
Challenging the Core Accretion Model
In standard planetary formation theory, growing worlds build an initial core out of rock and metal. Once an accumulating core reaches roughly 20 times the mass of Earth, its gravitational pull becomes strong enough to rapidly sweep up massive amounts of hydrogen and helium from the surrounding disk of gas and dust. This is the process that builds gas giants like Jupiter and Saturn in our own solar system.
GJ 523b sits squarely past that traditional threshold at 23.5 Earth masses, yet it failed to turn into a gas giant. Instead of an expansive gaseous envelope, computer simulations of its internal structure suggest the planet consists of an iron core accounting for roughly 37 percent of its mass, a silicate mantle making up 40 percent, a water-rich hydrosphere of about 21 percent, and only a minimal proportion of hydrogen and helium gas.
Translated from the original researcher statements, lead author Max Kroft noted that the object defies standard expectations.
Competing Scenarios for an Unprecedented World
The first suggests that two massive protoplanets collided violently, fusing their dense cores together while the intense heat of the impact blasted most of their gaseous envelopes out into space.
Adding to the list of anomalies, measurements indicate that the orbit of GJ 523b is tilted by at least 71 degrees relative to the equator of its host star, meaning it loops nearly directly over the stellar poles rather than traveling along the stellar equator.
Toward a New Planetary Classification
Astronomers have used the term mega-Earth
informally for over a decade to describe exceptionally massive rocky worlds, though it remains an unofficial category.
The manuscript detailing the discovery has been submitted for formal publication in The Astronomical Journal.
Ещё по этой теме
