Jakarta –
Astronomers discovered a solid iron planet, twice as dense as Earth. Its size is almost the size of Earth. This planet is thought to be ‘naked’ with only its core remaining.
This planet is an Ultra Short Period (USP) planet that orbits its star in just 7.7 hours. This planet, which is an exoplanet, aka outside the Solar System, is named Gliese (GJ) 367 b, aka Tahay, as reported by Science Alert, Thursday (22/9/2023).
Planet Tahay discovered in 2021
There are around 5,000 exoplanet catalogues, and 200 of them include USP. This Tahay was actually discovered by astronomers from TESS (Transiting Exoplanet Survey Satellite) satellite data in 2021. At that time astronomers detected a very weak transit signal from the red dwarf star Gliese 367. The signal was very weak at the limit of the TESS satellite’s detection capabilities. From the weak signal, astronomers know that this planet is small, similar in size to Earth.
Astronomers continued this discovery in 2021, examining Tahay, using the High-Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph at the European Southern Observatory to determine its mass and density.
As a result, astronomers found that the radius of the planet Tahay is 72% of Earth’s, and its mass is 55% of Earth’s mass. This means that it is very likely that the planet Tahay is an iron planet, leaving only the core of the planet which was once much larger.
However, astronomers’ latest discovery of this planet is the result of measuring the mass and radius of the planet Tahay. Astronomers also discovered two ‘siblings’ of the Tahay planet.
Latest Tahay Measurement Results
Most recently, astronomers, Elissa Goffo, PhD and colleagues at the Physics Department of the University of Turin in Italy, used HARPS to measure how small Tahay is. Goffo used 371 HARPS observations. The result, apparently, compared to the findings in 2021, Tahay’s mass increased from 55% to 63% of the Earth’s mass. Meanwhile, the planet’s radius is decreasing, from 72% to 70% of the Earth’s radius.
In essence, from the results of these latest measurements, the planet Tahay is twice as dense as Earth. Goffo concluded that it was possible that Tahay lost its rock layer, aka the rock mantle peeled off, leaving behind the planet’s core.
“You can compare GJ 367 b to an Earth-like planet whose rock layers have been peeled off,” said lead author Goffo.
“This could have important implications for the formation of GJ 367 b. We believe that this planet may have formed like Earth, with a solid core made mostly of iron, surrounded by a silicate-rich mantle,” continued Goffo.
The reason Planet Tahay remains is the point
What makes a planet lose its rock layers and remain only its core?
The first possibility, Goffo estimates that something big happened to this planet. Like a very powerful disaster that made the rock layers peel off.
“There may have been collisions between planets or with protoplanets (old planets) that occurred during the early formation of this planet,” wrote Goho.
The second possibility is that this planet formed in a region of the protoplanetary disk that is rich in iron. However, this second possibility is so small that it is impossible to happen.
The third possibility is that this planet is the remains of a gas giant planet like Neptune. If this third possibility occurs, then the planet will form further from its star and then migrate into the area of its star. Tahay is currently known to be so close to its star that the intense radiation from the red dwarf star would boil its atmosphere.
“Thanks to our precise mass and radius estimates, we explored the potential composition and internal structure of GJ 367 b and found that it is predicted to have an iron core with a mass fraction of 0.91,” Gofo wrote in his report.
Tahay’s 2 ‘siblings’ were found
The researchers also discovered two more planets in this system: G 367 c and d. This companion planet also orbits close to the star but has a lower mass. This lends weight to the idea that one of them formed in an iron-rich environment but does not eliminate it.
“Thanks to our intensive observations with the HARPS spectrograph, we discovered the existence of two additional low-mass planets with orbital periods of 11.5 and 34 days, which reduces the number of possible scenarios that might lead to the formation of such compact planets,” said Gofo fellow astronomer Prof Davide Gandolfi .
“While GJ 367 b probably formed in an iron-rich environment, we do not exclude formation scenarios involving violent events such as giant planetary collisions,” Gandolfi said.
Gofo and Gandolfi et al’s research on the planet Tahay entitled “Company for the Ultra-high Density, Ultra-short Period Sub-Earth GJ 367 b: Discovery of Two Additional Low-mass Planets at 11.5 and 34 Days” has appeared in The Astrophysical Journal Letters Volume 955 Number 1 on September 20, 2023.
Watch the video “Scientists Say Humans Have Pushed Earth into the ‘Planetary Boundary’ Danger Zone”
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2023-09-24 02:00:42
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