New planet named Enaiposha is unlike anything in our solar system
It started as another exoplanet in a group labeled “ordinary.” No one expected that a world, once thought to be a mini-Neptune, would reveal traits of a super-Venus and change how we see certain planetary types.
Astronomers used JWST data to learn more about an unusual place called Enaiposha, that orbits a red dwarf star about 47 light-years away from the Sun.
A surprising “super-Venus”
Enaiposha, that also goes by the identifier GJ 1214 b, was first placed in a category that normally describes small, gas-rich worlds. New observations, however, suggest that it is more like Venus but on a bigger scale.
Researchers propose calling it a super-venus because it appears to have a thick atmosphere composed of hydrogen, helium, water, methane and carbon dioxide.
This finding came from recent measurements that showed faint traces of molecules at key parts of the spectrum.
Why Enaiposha breaks the mold
Sub-Neptune planets that are smaller than Neptune in size are the most common type of planet known to exist in the Milky Way, but they are absent from the solar system.
They have atmospheres that consist of a variety of gases and atmospheric spectroscopy is used to analyze what gases are present.
Enaiposha differs from a typical sub-neptune in that its upper layers are blanketed by haze and aerosols.
This makes it very difficult to analyze the atmosphere spectroscopically to establish which gases form the atmosphere on the exoplanet.
Venus also has clouds that block most views of its surface, but Enaiposha takes this phenomenon further. It is bigger, hotter, and enveloped by layers that make it especially hard to examine.
An air that dims the light
When Enaiposha crossed between its star and Earth, tiny dips occurred at points on the spectrograph where certain gases absorb starlight.
The data hinted at a metal-rich atmosphere with less hydrogen floating around than scientists had expected.
One portion of the team’s work pointed that water vapor was present in the atmosphere, but that alone was not the big story.
Small signs of complex metals emerged, which is odd for a planet once categorized in a simpler way.
Furthermore, as starlight passed through Enaiposha’s outer layers (atmosphere), certain wavelengths of light were also absorbed that indicated the signatures of carbon dioxide and methane.
CO2 may be present on Enaiposha
The study was led by astronomers Everett Schlawin from the University of Arizona and Kazumasa Ohno from the National Astronomical Observatory of Japan (NAOJ).
The scientists got a faint clue that carbon dioxide may exist in concentrations akin to those found on Venus. They saw how light changed as it went through Enaiposha’s thick skies.
“The detected CO2 signal from the first study is tiny, and so it required careful statistical analysis to ensure that it is real,” noted Ohno, the team member leading the theoretical investigations.
Experts sometimes place planets slightly bigger than Earth in the super-earth bracket. Those even larger but still under Neptune’s mass sit in the mini-Neptune group.
This planet seems to occupy a weird middle zone. The findings have driven some scientists to propose that Enaiposha represents a new sub-type of exoplanet, or at least a neat twist on the usual groupings.
Haze gets in the way
Research on Enaiposha, a super-Venus, is still tough because of the haze. Observations pick up only subtle signals from deeper parts of its atmosphere.
A single measurement can be overwhelmed by the star’s brightness. Multiple follow-up sessions and new instruments may be needed to confirm all of these ingredients.
Why does any of this matter?
Some wonder whether similar planets hide in other star systems. It may be risky to assume that everything beyond our Sun fits neatly into known boxes.
Astronomers have found thousands of strange worlds. This one stands out for defying what was presumed normal in the mini-Neptune category of exoplanets.
One encouraging aspect is how these methods might apply to places that could harbor life. Enaiposha is scorching, so it is not a promising location for habitability.
Still, the process of analyzing its hazes and thick skies could help scientists interpret atmospheres around other exoplanets in less extreme locations. That matters for anyone seeking to detect breathable air anywhere beyond our own system.
Enaiposha and future exploration
Some want to see whether metals in Enaiposha’s air, as a super-Venus, can form droplets or complex clouds. That might explain why so little light passes through its atmosphere.
Others suspect it could be a stepping stone for modeling how thick atmospheres evolve. It might also show that sub-Neptunes can morph into something else with time.
In future, further modeling of the planet’s atmosphere, interior structure and origins will provide valuable insights about how sub-Neptunes like GJ 1214 b form and evolve.
The study is published in The Astrophysical Journal Letters.
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