Study Findings: A Carbon-rich Atmosphere on a Windy Pulsar Planet

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Image (Credit): Artist’s rendering of of an exoplanet orbiting a rapidly spinning neutron star called a pulsar. (NASA, ESA, CSA, Ralf Crawford (STScI))

Abstract of pre-publication study findings:

A handful of enigmatic Jupiter-mass objects have been discovered orbiting pulsars. One such object, PSR\,J2322-2650b, uniquely resembles a hot Jupiter exoplanet due to its minimum density of 1.8 g/cm^3 and its ~1900 K equilibrium temperature. We use JWST to observe PSR J2322-2650b’s emission spectrum across an entire orbit. In stark contrast to every known exoplanet orbiting a main-sequence star, we find an atmosphere rich in molecular carbon (C3, C2) with strong westward winds. Our observations open up new exoplanetary chemical (ultra-high C/O and C/N ratios of >100 and >10,000, respectively) and dynamical regimes (ultra-fast rotation with external irradiation) to observational study. The extreme carbon enrichment poses a severe challenge to the current understanding of “black widow” companions, which were expected to consist of a wider range of elements due to their origins as stripped stellar cores.

Citation: Michael Zhang et al. A carbon-rich atmosphere on a windy pulsar planet. ApJL (2025).

https://doi.org/10.48550/arXiv.2509.04558

Study-related stories:

University of Chicago – “NASA’s Webb Telescope Finds Bizarre Atmosphere on a Lemon-shaped Exoplanet”

Scientific American – “This Planet Is the Shape of a Lemon. That May Be the Least Weird Thing about It”

Space Daily – “Webb Maps Carbon Rich Atmosphere on Distorted Pulsar Planet”

Pic of the Week: Wolf-Rayet Apep

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Image (Credit): Dust spirals surrounding Wolf-Rayet Apep, as captured by the JWST. (NASA, ESA, CSA, STScI, Y. Han (Caltech), R. White (Macquarie University), A. Pagan (STScI))

This week’s embryonic image comes from the James Webb Space Telescope (JWST). It shows what NASA calls “four serpentine spirals of dust” around a pair of Wolf-Rayet stars. Such stars are rare, with NASA estimating that only a thousand can be found in our galaxy consisting of hundreds of billions of stars. And binary Wolf-Rayet stars are even rarer.

NASA notes that the JWST, or Webb, provided a much better image of the spiraling dust:

Observations taken prior to Webb only detected one shell, and while the existence of outer shells was hypothesized, searches using ground-based telescopes were unable to uncover any. These shells were emitted over the last 700 years by two aging Wolf-Rayet stars in a system known as Apep, a nod to the Egyptian god of chaos...Webb also confirmed that there are three stars gravitationally bound to one another in this system. The dust ejected by the two Wolf-Rayet stars is “slashed” by a third star, a massive supergiant, which carves holes into each expanding cloud of dust from its wider orbit. (All three stars are shown as a single bright point of light in Webb’s image.)

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?”

Pic of the Week: Pismis 24

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Image (Credit): The Pismis 24 star cluster as captured by the JWST. (NASA, ESA, CSA, and STScI, A. Pagan (STScI))

This week’s amazingly vibrant image was captured by the James Webb Space Telescope (JWST). It shows a young star cluster, called Pismis 24, which is approximately 5,500 light-years away.

Here is the rest of the story from the European Space Agency (ESA):

What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. This region is one of the best places to explore the properties of hot young stars and how they evolve.

Pic of the Week: Cat’s Paw Nebula

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Image (Credit): NASA’s JWST poster showing the Cat’s Paw Nebula. (NASA, ESA, CSA, STScI; Designer: Elizabeth Wheatley (STScI))

This week’s image highlights a NASA poster that you can download (in a variety of versions). It shows the Cat’s Paw Nebula (NGC 6334) as captured by the James Webb Space Telescope (JWST).

Here is a short summary of what you are seeing from NASA:

Located approximately 4,000 light-years away in the constellation Scorpius, the Cat’s Paw Nebula offers scientists the opportunity to study the turbulent cloud-to-star process in great detail. Webb’s observation of the nebula in near-infrared light builds upon previous studies by NASA’s Hubble and retired Spitzer Space Telescope in visible- and infrared-light, respectively.

With its sharp resolution, Webb shows never-before-seen structural details and features: Massive young stars are carving away at nearby gas and dust, while their bright starlight is producing a bright nebulous glow represented in blue. It’s a temporary scene where the disruptive young stars, with their relatively short lives and luminosity, have a brief but important role in the region’s larger story. As a consequence of these massive stars’ lively behavior, the local star formation process will eventually come to a stop.

For more details and videos, visits the NASA page on the Cat’s Paw Nebula, which helps to commemorate the third anniversary of the JWST.