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The story
A research team at Kagoshima University has announced that, based on ALMA telescope observation data, a theoretical model suggests the dust around the still-forming exoplanet “PDS 70c” may be distributed in a ring shape rather than a disk. Dust had previously been predicted to spiral inward toward the planet and thin out over time, but the observations contradicted this — and the newly proposed ring structure offers a hypothesis to explain the discrepancy. The study drew attention as a clue to how exomoons might form, and on 5ch, commenters carefully quoted the original article’s explanatory passages while tracing the reasoning, with some describing the ring structure as “like a world of smoke rings.”
Possible ring-shaped “moon-building material” found around a still-forming exoplanet — Kagoshima University
Several candidate exomoons have been found so far, but none has been confirmed.
Against that backdrop, Kagoshima University announced on September 4 that observations with the ALMA telescope, combined with theoretical modeling, revealed that dust around the still-forming exoplanet “PDS 70c” — one of very few such planets ever observed — is distributed not as a disk but in a ring (a dust ring).
Source: news.mynavi.jp / Original article here
What people said
Smoke rings are dying star systems, so they're nothing like the newborn one in Re: #1.
>>The discovery of exoplanets greatly advanced planet-formation theory. But most exoplanets found so far have already finished forming, so observing the formation process itself has been difficult until recently.
>>The young T Tauri star "PDS 70," which is still in the process of forming, is known to host two planets: "PDS 70b" and "PDS 70c." Both are among only about ten confirmed still-forming exoplanets found so far. Both are thought to be giant gas planets with thick atmospheres, similar to Jupiter and Saturn in our solar system, and are currently accumulating gas from the surrounding "protoplanetary disk."
>>In recent years, ALMA has detected PDS 70c at multiple wavelengths, suggesting that its circumplanetary disk is "optically thick" in the submillimeter/millimeter band. Optically thick means there's so much dust in the disk that you can't see through to the other side.
Background and key points of this topic
PDS 70 is one of the few celestial objects where the “site of planet formation” can be directly observed, with only about ten confirmed still-forming exoplanets known worldwide. Among them, PDS 70c is the only one also detected in radio wavelengths, and its surrounding dust was known to be “optically thick.” That conflicted with the usual theoretical prediction that dust should lose angular momentum to gas drag and spiral inward toward the planet (the drift process), thinning out over time — and this study set out to resolve that contradiction. What it found was that the dust may be gathered into a ring rather than spread evenly across a disk, which could eventually serve as raw material for a moon. That said, this is currently just an estimate from a theoretical model based on ALMA data — the ring structure and the “material” itself have not been directly observed or confirmed, which is easy to misunderstand. The prediction is expected to be clearly testable once the next-generation “ngVLA” radio telescope, targeted to begin operating in the 2040s, comes online. Thread reactions mostly consisted of careful quoting of the research content, with no notable points of disagreement.
※This article is excerpted and summarized from the 5ch (Science News+) thread “Possible ring-shaped “moon-building material” found around a still-forming exoplanet — Kagoshima University.”
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