Study Findings: Not All Sub-Neptune Exoplanets Have Magma Oceans

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Credit: Image by Enrique from Pixabay

The Astrophysical Journal Letters abstract of the study findings:

The evolution and structure of sub-Neptunes may be strongly influenced by interactions between the outer gaseous envelope of the planet and a surface magma ocean. However, given the wide variety of permissible interior structures of these planets, it is unclear whether conditions at the envelope–mantle boundary will always permit a molten silicate layer or whether some sub-Neptunes might instead host a solid silicate surface. In this work, we use internal structure modeling to perform an extensive exploration of surface conditions within the sub-Neptune population across a range of bulk and atmospheric parameters. We find that a significant portion of the population may lack present-day magma oceans. In particular, planets with a high atmospheric mean molecular weight and large envelope mass fraction are likely to instead have a solid silicate surface, since the pressure at the envelope–mantle boundary is high enough that the silicates will be in solid postperovskite phase. This result is particularly relevant given recent inferences of high-mean molecular weight atmospheres from JWST observations of several sub-Neptunes. We apply this approach to a number of sub-Neptunes with existing or upcoming JWST observations and find that in almost all cases, a range of solutions exist that do not possess a present-day magma ocean. Our analysis provides critical context for interpreting sub-Neptunes and their atmospheres.

Citation: Bodie Breza et al. Not all sub-Neptune exoplanets have magma oceans. ApJL 993 L46 (2025).

https://doi.org/10.3847/2041-8213/ae0c07

Study-related stories:

Universe Today – “It Looks Like All Mini-Neptunes Aren’t Magma Oceans After All”

University of Chicago – “New Study Revises Our Picture of the Most Common Planets in the Galaxy”

Space.com – “Is Our Dream of Finding Ocean-Covered Exoplanets Drying Up?”

Space Stories: New Exoplanets in a Binary Star System, the Secret “Athena” Plan for NASA, and an Interstellar “Tunnel”

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Credit: Pixabay.com.

Here are some recent space-related stories of interest.

—University of Liege: “Three Earth-sized Planets Discovered in a Compact Binary System“

An international team of researchers has just revealed the existence of three Earth-sized planets in the binary stellar system TOI-2267 located about 190 light-years away. This discovery, published in Astronomy & Astrophysics, is remarkable as it sheds new light on the formation and stability of planets in double-star environments, which have long been considered hostile to the development of complex planetary systems.

—ARSTECHNICA: “Capitol Hill is Abuzz with Talk of the “Athena” Plan for NASA“

In recent weeks, copies of an intriguing policy document have started to spread among space lobbyists on Capitol Hill in Washington, DC. The document bears the title “Athena,” and it purports to summarize the actions that private astronaut Jared Isaacman would have taken, were his nomination to become NASA administrator confirmed. The 62-page plan is notable both for the ideas to remake NASA that it espouses as well as the manner in which it has been leaked to the space community.

—Earth.com: “Interstellar “Tunnel” Found that Connects Our Solar System to Other Stars, According to Astronomers“

Space can surprise even those who spend their lives studying it. People often think of our solar system as just a few planets and a bunch of empty space. Yet new observations suggest we have been living inside a hot, less dense region, and that there may even be a strange “cosmic interstellar channel,” or tunnel, connecting us to distant stars. After years of careful mapping, a new analysis reveals what appears to be a channel of hot, low-density plasma stretching out from our solar system toward distant constellations.

RIP: June Lockhart, Actress

Posted on by onespaceman2000
Image (Credit): June Lockhart in the television series Lost in Space. (20th Century Fox Television)

Actress June Lockhart passed away last Thursday at the age of 100. She had a storied career in both movies and television, including the 1960s television shows Lassie and Lost in Space.

Lost in Space was a somewhat silly story about the Robinson family migrating from an overpopulated Earth to a exoplanet orbiting Alpha Centauri. Of course, just like the story in Gilligan’s Island, the five-and-a-half year tour turned into a new adventure among the stars.

The show was best known for the robot always spouting “Danger, Will Robinson!” in reference to the son whose mother was played by June Lockhart. Of course, Star Trek premiered during that same period with some of the same silliness. It seems we did not achieve our darker sentiments about humans in space until somewhat later.

With regard to her time with Lost in Space, Ms. Lockhart stated to Fox News:

I was over the moon – pun intended. … I have been told that my contribution inspired many astronauts to pursue a career in space science and exploration … it is lovely to know that I touched so many people by doing things that interested me!

The 1998 movie Lost in Space did little to revive interest in the series (or space from what I can tell), but the Neflix television series of the same name did a nice job bringing the Robinson family back to life. If you are looking for a great updated adventure story about a boy and his robot traveling through space, you might want to start with the Netflix version.

You can read more on Ms. Lockhart’s life and career at these sites:

BBC
CBS News
The New York Times

Rest in peace.

Image (Credit): Poster for the 1998 movie Lost in Space. (New Line Cinema)
Image (Credit): Poster for the 2018 television series Lost in Space. (Netflix)

Potential Exomoon Being Studied by JWST

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Image (Credit): Artist’s rendering of WASP-39b. (NASA, ESA, CSA, Joseph Olmsted (STScI))

We hear plenty about all the exoplanets being studies at the moment, but we hear very little about exomoons, though several astronomers are eager to find them and learn more about them.

This time last year I highlighted a paper that discussed a possible exomoon circling an exoplanet called WASP-49Ab located about 635 light-years away . It was spotted by the European Southern Observatory’s Very Large Telescope in Chile.

Well, now the James Webb Space Telescope (JWST) has provided data related to another possible exomoon orbiting a hot Jupiter-like exoplanet called WASP-39b. It is located about 700 million light-years away.

In a Scientific American article titled “Have Astronomers Finally Found an Exomoon?” we learn that a paper is being released shortly outlining the argument for this potential “hypervolcanic exomoon.” This presumed IO-like exomoon is being cooked by the parent sun.

The paper accepted for publication, Volcanic Satellites Tidally Venting Na, K, SO2 in Optical & Infrared Light, states the following:

Recent infrared spectroscopy from the James Webb Space Telescope (JWST) has spurred analyses of common volcanic gases such as carbon dioxide (CO2), sulfur dioxide (SO2), alongside alkali metals sodium (Na I) and potassium (K I) surrounding the hot Saturn WASP-39 b. We report more than an order-of-magnitude of variability in the density of neutral Na, K, and SO2 between ground-based measurements and JWST, at distinct epochs, hinting at exogenic physical processes similar to those sourcing Io’s extended atmosphere and torus. Tidally-heated volcanic satellite simulations sputtering gas into a cloud or toroid orbiting the planet, are able to reproduce the probed line-of-sight column density variations. The estimated SO2 flux is consistent with tidal gravitation predictions, with a Na/SO2 ratio far smaller than Io’s. Although stable satellite orbits at this system are known to be < 15.3 hours, several high-resolution alkali Doppler shift observations are required to constrain a putative orbit. Due to the Roche limit interior to the planetary photosphere at ~ 8 hours, atmosphere-exosphere interactions are expected to be especially important at this system.

It is a dense summary, but also a hopeful finding that may lead to more focused searches for exomoons.

The addition of exomoons to the list of new discoveries will only increase the chances that some form of life can be found among he many solar systems we can study. Interestingly enough, we are still probing our own solar system’s moons with the same hope.

Space Stories: Questionable Move of Space Shuttle Discovery, the Problem with Red Dwarf Exoplanets, and a Rare Sight from Mars

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Image (Credit): Space shuttle Discovery landing at Edwards Air Force Base in California. (NASA)

Here are some recent space-related stories of interest.

—Chron: “Historic Space Shuttle Could Be Compromised for Trip to Texas“

Within the next 18 months, the space shuttle Discovery may be disassembled in Washington D.C., transported more than 1,000 miles to Houston and reassembled. But not if grassroots group Keep The Shuttle has anything to say about it. The plan to move a shuttle, notably an unnamed shuttle, was part of President Donald Trump’s “Big Beautiful Bill” passed this summer. The Smithsonian and others have dug in against the move, saying the research institute actually owns the Discovery in a trust for the American people, nothing that it’s unclear if Congress even has the authority to order the Smithsonian transfer an artifact.

—Universe Today “New Research Suggests Red Dwarf Systems are Unlikely to Have Advanced Civilizations“

Thanks to the huge spate of exoplanet discoveries, multiple rocky planets have been found orbiting within the habitable zones (HZs) of red dwarf stars. For decades, there has been an ongoing debate as to whether these systems could be our best bet for finding evidence of life beyond Earth. In a recent study, Professor David Kipping addresses two key facts that could mean humanity is an outlier. Based on the age of the Universe and the relatively rare nature of our Sun, he concludes that astrobiologists examining red dwarf planets may be looking in the wrong place.

—CBS News: “Interstellar Comet Passing by Mars Seen in Rare Images“

A rare interstellar comet — only the third ever confirmed to enter our solar system — was photographed last week, closely approaching Mars, the European Space Agency said Tuesday. The images taken on Friday by two Mars orbiters show a bright, fuzzy white dot of the comet, also known as 3I/ATLAS, appearing to move against a backdrop of distant stars as it was about 18,641,135 miles away from Mars. The comet poses no threat to Earth, NASA has previously said.