We have so few exoplanets that can actually be seen rather than inferred through other data that the recent news concerning the star TWA 7 resonates. The James Webb Space Telescope provided the data on a gap in one of the rings found around this star, with the debris disk itself imaged by the European Southern Observatory’s Very Large Telescope as per the image below. The putative planet is the size of Saturn, but that would make it the planet with the smallest mass ever observed through direct imaging.
Image: Astronomers using the NASA/ESA/CSA James Webb Space Telescope have captured compelling evidence of a planet with a mass similar to Saturn orbiting the young nearby star TWA 7. If confirmed, this would represent Webb’s first direct image discovery of a planet, and the lightest planet ever seen with this technique. Credit: © JWST/ESO/Lagrange.
Adding further interest to this system is that TWA 7 is an M-dwarf, one whose pole-on dust ring was discovered in 2016, so we may have an example of a gas giant in formation around such a star, a rarity indeed. The star is a member of the TW Hydrae Association, a grouping of young, low-mass stars sharing a common motion and, at about a billion years old, a common age. As is common with young M-dwarfs, TWA 7 is known to produce strong X-ray flares.
We have the French-built coronagraph installed on JWST’s MIRI instrument to thank for this catch. Developed through the Centre national de la recherche scientifique (CNRS), the coronagraph masks starlight that would otherwise obscure the still unconfirmed planet. It is located within a disk of debris and dust that is observed ‘pole on,’ meaning the view as if looking at the disk from above. Young planets forming in such a disk are hotter and brighter than in developed systems, much easier to detect in the mid-infrared range.
In the case of TWA 7, the ring-like structure was obvious. In fact, there are three rings here, the narrowest of which is surrounded by areas with little matter. It took observations to narrow down the planet candidate, but also simulations that produced the same result, a thin ring with a gap in the position where the presumed planet is found. Which is to say that the planet solution makes sense, but we can’t yet call this a confirmed exoplanet.
The paper in Nature runs through other explanations for this object, including a distant dwarf planet in our own Solar System or a background galaxy. The problem with the first is that no proper motion is observed here, as would be the case even with a very remote object like Eris or Sedna, both of which showed discernible proper motion at the time of their discovery. As to background galaxies, there is nothing reported at optical or near-infrared wavelengths, but the authors cannot rule out “an intermediate-redshift star-forming [galaxy],” although they calculate that probability at about 0.34%.
The planet option seems overwhelmingly likely, as the paper notes:
The low likelihood of a background galaxy, the successful fit of the MIRI flux and SPHERE upper limits by a 0.3-MJ planet spectrum and the fact that an approximately 0.3-MJ planet at the observed position would naturally explain the structure of the R2 ring, its underdensity at the planet’s position and the gaps provide compelling evidence supporting a planetary origin for the observed source. Like the planet β Pictoris b, which is responsible for an inner warp in a well-resolved—from optical to millimetre wavelengths—debris disk, TWA 7b is very well suited for further detailed dynamical modelling of disk–planet interactions. To do so, deep disk images at short and millimetre wavelengths are needed to constrain the disk properties (grain sizes and so on).
So we have a probable planet in formation here, a hot, bright object that is at least 10 times lighter than any exoplanet that has ever been directly imaged. Indeed, the authors point out something exciting about JWST’s capabilities. They argue that planets as light as 25 to 30 Earth masses could have been detected around this star. That’s a hopeful note as we move the ball forward on detecting smaller exoplanets down to Earth-class with future instruments.
Image: The disk around the star TWA 7 recorded using ESO’s Very Large Telescope’s SPHERE instrument. The image captured with JWST’s MIRI instrument is overlaid. The empty area around TWA 7 B is in the R2 ring (CC #1). Credit: © JWST/ESO/Lagrange.
The paper is Lagrange et al., “Evidence for a sub-Jovian planet in the young TWA 7 disk,” Nature 25 June 2025 (full text).
Addendum: I’ve just become aware of Crotts et al., “Follow-Up Exploration of the TWA 7 Planet-Disk System with JWST NIRCam,” accepted for publication at Astrophysical Journal Letters (preprint). From which this:
…we present new observations of the TWA 7 system with JWST/NIRCam in the F200W and F444W filters. The disk is detected at both wavelengths and presents many of the same substructures as previously imaged, although we do not robustly detect the southern spiral arm. Furthermore, we detect two faint potential companions in the F444W filter at the 2-3σ level. While one of these companions needs further followup to determine its nature, the other one coincides with the location of the planet candidate imaged with MIRI, providing further evidence that this source is a sub-Jupiter mass planet companion rather than a background galaxy. Such discoveries make TWA 7 only the second system, after β Pictoris, in which a planet predicted by the debris disk morphology has been detected.
Good to know this about TWA 7/CE Antliae! Looking forward to further news!
Lagrange et al, a case of nominative determinism?😉
Is there a possibility to look for moons orbiting around this planet? Presumably if it is the size of Saturn it has some, and since we can observe it directly might we be able to use some of the same methods we use to look for planets around stars?
@Alastair
Given how faint the signal is, and in several analyses, the residual pixel values after processing, there seems to be little hope for detecting any moons. As the system is viewed from a pole, the moon[s] would be orbiting the planet such that the transit method is ruled out. The planet might have tint deviations in its orbit, but the barycenter of this movement would be within the planet’s radius. This makes me doubtful a moon could be detected this way, even with much higher resolution. Eventually, it might be possible to image a moon[s] directly as they sort of have the planet, but the telescopes would have to have far better resolution to even have a stab at this approach.
As we can already just about detect planetary moons with the transit method, it seems to me that if you want to find and characterize moons of gas or ice giants, the transit method is your best bet. This also does not rule out Doppler shift of the planet’s motion due to the moon[s], and direct observation by higher-resolution telescopes in the future.
[If I am wrong, could one of the astronomy experts correct me?]
These figures are easy to misinterpret at first glance. That star, behind the corongraph, is almost the radius of the Sun, and the distance to that ring is 25 AU! So the planet, even the size of Saturn, is “really” only a pixel in size; we see it looking like it’s 5 AU across because it’s not perfectly resolved. Similarly, the moth-eaten spot in the ring isn’t an actual circle – anything slightly in or out would not revolve synchronously with the planet. Rather, the ring material is fuzzy, like the planet, leading to the illusion of a round hole, and it’s just that the planet creates a large gap in the ring where the orbit wouldn’t be stable. Please correct me if I’m wrong…
IIUC, you are saying that a planet should sweep out a ring of material, creating a gap ring such as we see in images of dust around a star. That this does not appear to be the case in this instance, just a local gap in the dust, implies it isn’t a planet. Is that correct?
Sorry, I could have written that one better. I meant that AFAICT the white roughly circular rings at CC#1 aren’t actually part of any planet or ring system. I think the clearest visualization is on the right side of Figure #3 in the Nature article, where the planet is marked with a red dot. In that figure it looks like there are Trojans, Greeks, and very many miscellaneous horseshoes sharing that planet’s orbit. This makes sense; after all, the current model of the Earth/Moon’s formation is that Theia grew to the size of Mars in one of those positions before crashing into Earth.
Hopefully something will show up in the infra red spectra of the exoplanet TWA 7b’s atmosphere like some heavier gases. Maybe we will see some methane or ethane.
As a follow through off-topic unsolicited update as to the ongoing project of a proposed constitution for an – eventual – Mars settlement (at least the current topic concerns a putative planet) . . .
* * * * * * * *
I have no idea now when we may be sending even the first crewed ship to Mars. At least as a government-facilitated operation.
Musk clearly is no Niccolò Machiavelli.
Meanwhile, even before the bloom was off the rose between the billionaires, I wasn’t going to make my end of June target for having both the proposed constitution and also all of the Federalist Papers type explanatory essays finished.
The proposed constitution currently weighs in at almost 24,000 words. And it is a complete working document that, in a pinch, conceivably could be put into effect tomorrow (well, if there was a settlement up there). It’s that close to full baked, although I’m still refining the proposal here and there as I work on the essays.
The essays – in contrast – still have a ways to go collectively.
The 85 essays in the Federalist Papers totaled approximately 200,000 words (per Grok), on a less than 5000 word U.S. Constitution. The hard copy book from my family’s ancestral library, the one that I read as a kid, is 488 pages long.
I currently have 28 essays in near final working draft form, totaling about 61,000 words, along with a number of bits and pieces of other draft material for working up into other essays. (So I’m running about par for the course on the volume of the explainer content, with the individual essays of course varying in length both in 1788 and now.)
The ongoing dialectic with myself (I truly do need to get out more) in writing the essays does help improve the otherwise completed constitution.
So, for that as well as other reasons, I’ll hold everything until I’m done with the lot.
I targeted the end of June this year because that lined up with the Mars Society’s abstract deadline for papers heading into its mid-October annual convention over at USC (I’m just up the road a bit in Las Vegas).
The running game plan was to: (1) get the finished proposed constitution and essays up on a website established for that purpose, so that they can be readily linked to; (2) submit the initial debut cover article here (also currently in working draft) for review by Paul, and then (3) tender an abstract (also ready in draft) to the Mars Society to ultimately follow through there for October.
But it will take me more than the rest of this summer – and then some – to finish everything in order to then be in position to submit a debut article for review here. So I’ll aim for the same basic early summer target and timeline for 2026. Perhaps moving things up a bit within 2026 if I get everything to completion sooner.
I plan to submit ultimately about four or five articles for Paul’s review here discussing various broad themes re: the overall proposal, with an eye toward hopefully generating discussion more about – Mars – rather than Earth. (One can hope anyway as to that.)
I know that I’m doing a bit of a . . . uh . . . yes . . . Musk . . . by setting targets and then moving them back.
But at the risk of sounding like also Yogi Berra, it ain’t ready ‘til it’s ready.
Meanwhile, I’ve been working steadily, and enjoying the work.
But part of the reason the project got shelved years back was the amount of work involved to do these essays. The same basic effort – in terms of what they were trying to do via the essays – produced literally a book in the aggregate in 1788.
Every essay that I complete, though, gets me one step closer.
I can empathize with Michael Chorost with his long term science fiction project as to the ant-like extraterrestrials.
You reach a point where it’s “if not now, when” in terms of working the project through to completion.
So not now as to completion just yet, but now as to keeping working toward that end.
Mars still will be there.
And it’s looking at the moment like the entirety of humanity also still will be on Earth in the meantime.
When you write your essays for CD, perhaps you can include a “compare and contrast” with other constitutions, e.g., the US and EU, at least with regard to major departures. Also, as Mars is hostile to humans, note any clauses that are responsive to that situation. As a finale, perhaps add in whether the Mars constitution could be adapted for other planets and moons, even space habitats, or just copied wholesale. Do any provisions conflict with existing space Law? If space colonization becomes purely corporate, then what?
I’ll definitely keep those suggestions in mind, Alex.
The compare and contrast element is there, particularly as to the U.S. Constitution, as that’s the underlying model as to the order of the provisions (e.g., starting with legislative authority as in Article I of the U.S. Constitution) and – to an extent – also their substance. So when the proposal is departing from the U.S. model as to substance – which it does extensively – it’s thus natural in the essays to discuss what’s being done differently and why.
I’ll put on the project to-do list to also consider including express compare-and-contrast as to other constitutions. And I’ll look at that in relation to how that ties in with the proposal’s core concepts. That is, the proposed constitution flows from core concepts which are outlined primarily in the first group of essays, such as quite probably the centerpiece essay on direct democracy itself, from ancient Athens on. Before the following groups of essays then go through the particulars of the proposed constitution more so from stem to stern. So I’ll look at maybe a discrete essay comparing and contrasting the document overall – as derived from those core concepts – to sundry other constitutions. But, as I say, as to the U.S. Constitution, both with respect to core concepts and then once we’re into the nuts and bolts of the provisions, that compare and contrast element is a natural component of the discussion.
As to the hostile environment, that of course is the continuous backdrop, as the thing explicitly is designed – as one of those core concepts – to function from sol one on, from figuratively when the boots of the first intentionally permanent settlers hit Martian regolith on. So that’s the constant backdrop, as to what can be done in terms of a system of governance by at first only a handful of people clustered together in hab units with an instantaneously unforgiving environment outside.
So, for example, a judicial system such as was contemplated by the U.S. Constitution is not a practical option at all initially. The proposal thus strips the judicial “system” way, way, way down to initially a bare bones manner of resolving disputes as fairly and reliably as possible under the circumstances. With much more specificity than that brief theoretical description – that’s part of why it’s 24,000 words rather than 5,000. But that’s the net result, a highly stripped down judicial system, i.e, means of dispute resolution. That nascent bare bones structure eventually evolves – per specifically spelled-out stages in the proposal – into a fully functioning and independent judiciary preserving the rule of law as one check on the potential excesses of a primarily direct democracy.
But the proposal strives to not put anything down on paper – with very high-sounding ideals and proclamations – that won’t work on the ground, in that harsh Martian environment, from that sol one forward. As I say, that’s one of those core concepts. It has to work from sol one on. In – contrast – for example to something like the French Déclaration des droits de l’Homme et du citoyen de 1789, which tended to be more long on principle and short on practicality. Unlike that document, the proposal seeks to be practical more so than merely aspirational. This sol, not some sol.
Yes, the proposal explicitly is intended to serve as a template for other off-world (as to Earth) human settlements. The things that would be changed for those contexts would be functionally incidental matters such as time periods – sols, Martian years and the like. But the structure itself is designed as an otherwise plug-and-play model for any and all other off-world human settlements, such as a permanent settlement on the Moon, at the cloud tops of Venus, and, yes, also in O’Neill cylinders.
That’s basically what takes all the work. Tailoring a structure of governance – at least one that seeks to project democracy and individual worth and freedom out into the cosmos – to the context of settlements formed from scratch in an off-world environment.
As to space law, probably the most tension between Terran space law and the proposal is the core concept in the proposal that – frankly insists – on exercising a fundamental human right of self-governance and self-representation. Terran treaties seek to prevent the assertion of Terran-based sovereignty – including by any group of ostensibly private settlers originating from a Terran sovereignty, such as whoever jumps on one of Musk’s Starships – out into the cosmos. The proposed constitution, in broad brush, seeks to address that tension by explicitly extending the right of self-governance only to the structures that they occupy and use on, here, Mars, as opposed to asserting a national sovereignty or jurisdiction over all or part of Mars itself. I have an essay as to that that works through the underlying details of what the applicable treaties specifically provide and what the proposal specifically provides. But that’s the nut of it.
And that’s a hard line position by me, as the proponent of what I recommend for the Martian settlers. At the end of the proverbial sol, denying settlers on other worlds (or free-floating space habitats) a fundamental human right of self-governance and self-representation just – whether intended or not – extends a new form of Terran imperialism and colonialism out into the stars. “One world to rule them all.” I don’t think so. But the specifics of the proposal try to work all that out consistently with – rather than in derogation from – the treaty provisions. That’s just where I see the primary tension to be, at least in some folks’ eyes, as I do strive to work within the applicable treaties.
Corporate colonization is part of my – rush, such as it is – to get a coherent and fully thought through alternative proposal out there, one hopefully avoiding, inter alia, a corporate run world. Musk reportedly has hired a gaggle of space lawyers to prepare a constitution for Mars. I haven’t seen that they – or anyone else for that matter – has published anything or what such a constitution might include. But, shall we say, I’ve seen enough otherwise to conclude that having an independently prepared alternative proposal would not be a bad thing.
There are many things in life that proceed slowly, and then all at once. I’m trying to get ahead of the all at once part of that, for whatever contribution my independent proposal might provide to the overall process conducted hopefully ultimately by the Martian settlers themselves.
Anyway, I was trying to nestle this update into the mostly quiet space between the discussion of two succeeding articles here on Centauri Dreams, so as to not unintentionally hijack either discussion. Give me a “spot” of time here, everyone, and I think that you’ll find that the final proposal indeed will cover a fair amount of the waterfront.
But doing that – and also doing the explainer essays for that, which are just as critical – just takes time. Even when, as the writer, you can see the entire structure together as an integrated and interrelated conceptual whole, working from the regolith up.
Meanwhile, it’s on to Sedna, with its cornucopia of perhaps primordial, or maybe instead also interstellar, tholins. I was intrigued by the reference in its Wikipedia article that the dwarf planet “is one of the reddest known among Solar System bodies,” quite likely due to those tholins. If we can get a lander on there, one can only imagine the science . . . .
Based on your word estimates alone, you might just be overthinking and overpreparing the project. The US Constitution was erected as a structural and procedural framework to operate a contiguous, living government. I have a publication titled “Documents of Revolution”, which includes:
1. “Common Sense” by Thomas Paine
2. The Declaration of Independence
3. The Federalist Papers
4. The Anti-Federalist Papers
5. The Articles of Confederation
6. The U. S. Constitution
7. The Bill of Rights
So over 300,000 words of published discourse and debate, by several dozen well and diversely educated persons, to produce a document less than 10,000 words long, that has endured for 2.5 centuries, is a nigh-unmatchable feat of statesmanship and civilized society.
In its wake, and for comparison, the size of the US Code is estimated at over 2 billion words on 225 million pages of text in 10pt. font. Which serves to validates the idea that no amont of law can adequately cover every concievable situation from the outset; it must develop as its society (d)evolves.
It is really no different from a crew that lands on an uninhabited land mass and chooses to settle there rather than return home. There are vast differences in the survival and resource/logistics problems, many of which need preplanned solutions, but the fundaments of self-governance are not widely different from those of self-sufficiency. So, while your project sounds very interesting, it is as likely to be practically useful as a solo translation of one of humanity’s great works, such as “The Art of War” or the Book of Job. The greatest and most definitive influences on human civilization are often collaborative or collective as individual, as the juxtaposition of the accomplishments of the Greeks collectively with those of Alexander the Great, or of the various writings in the Mahabharata with those of Bhudda or Ghandi, or of the Judeo-Christian writers with the lives of David son of Jesse or Jesus of Nazareth. Each of these sets can be seen as the influence of a culture flowing through a leader as its focal point. For analogy the best comparison we have on earth to settling Mars is settling Antarctica, which has never officially been done as it has no accessible natural resources to speak of. So the ecplorers Roald Amundsen and Ernest Shackleton might be worthwhile figures to study in context.
“Based on your word estimates alone, you might just be overthinking and overpreparing the project.”
. . . . .
“So, while your project sounds very interesting, it is as likely to be practically useful as a solo translation of one of humanity’s great works, such as ‘The Art of War’ or the Book of Job.”
. . . . .
“For analogy the best comparison we have on earth to settling Mars is settling Antarctica, which has never officially been done as it has no accessible natural resources to speak of. So the ecplorers [sic] Roald Amundsen and Ernest Shackleton might be worthwhile figures to study in context.”
* * *
Perhaps.
I had two purposes in the comments about the Mars project here under this article.
The first initially was to provide – as a courtesy – an update because I had indicated earlier that I was shooting for the end of June 2025 to be publication ready.
Have never much liked it when people provide a target date for completing a project and then go silent when the target date passes. So that part was a courtesy.
The second purpose – more so in my nonetheless intended to be polite response to Alex – frankly was to then deflect another discussion – in the abstract and in the blind – about various and sundry about the project.
In part to not get into a detailed discussion about work product with folks who necessarily haven’t actually seen a . . . single . . . word in the proposal.
Even if there a truly functional point to doing that, I also didn’t want to wind up hijacking the discussion regarding the article at hand.
* * *
Meanwhile, I would note the following as to word counts and such, with the content below coming from mostly a working draft of an early essay from the general section of the – not-yet-published – essays.
Yes, constitutions are intended to be general documents, generally speaking.
They, again generally, are intended to establish a general structure of governance, leaving to the then political process established by the constitution – and primarily legislation – the task of addressing specifics within that structure.
That’s – generally – true but not always the case in practice.
For example, the 1789 Constitution tends very much toward a general document. There are a bit over 4400 words in the body of the main document, including divider words like “article” and “section.” The Bill of Rights added less than 500 words, so under 5000 words total for the original package as adopted early on.
The average U.S. state constitution, in contrast, is about five times longer, at 26,000 words; and the longest – Alabama’s – weighs in around a colossal 376,000 words.
(If one would prefer to compare the length of national constitutions, the 1950 Indian constitution is “about 145,000” words long, the second longest constitution of any type in the world, after Alabama’s. See, e.g., “Constitution of India” Wikipedia entry, as of 03/23/25.)
And those on average 26,000 word long state constitutions thus necessarily “tend to address somewhat more detail” than the 1789 Constitution.
So, at least in actual practice, there’s a fair amount of flexibility involved in how specific a constitution can be.
Although, yes, the – general – idea is that it’s intended to be a general, foundational document.
U.S. states of course deal with a different type of government than the U.S. national government, having in theory broader legislative authority – what’s called general police power – than the national government and addressing far more localized governmental concerns.
So it’s perhaps not entirely surprising that the – yet-to-be-actually-proposed -constitution trends in length more toward a U.S. state constitution than the 1789 Constitution.
Given that the – yet-to-be-actually-proposed – constitution in a sense has to cover the bases for both types of constitutions, establishing a structure of governance for an initially quite small locality but also one for essentially a national government standing on its own vis-à-vis other nation states out in the firmament and possibly also on Mars.
Also consider this.
The first Martian settlers won’t have a gaggle of lawyers standing by at their beck and call (well, for a price).
Or a bunch of well-heeled non-governmental organization (NGO) representatives right there in the ready.
And their interplanetary internet may be at best time-delayed, less extensive initially than the Terran internet, and subject to comms loss interruption.
The – yet-to-be-actually proposed – constitution is not intended to be a document that the settlers just ratify, pop a few corks over, and then stick in a drawer somewhere until some Martian lawyer eventually fishes it out years later to file a lawsuit with.
No, it’s essentially the instruction manual for setting up a system of self-governance from scratch on a new world.
One can imagine a group of settlers huddled together in a hab with the wind howling outside from a dust storm that’s currently on sol thirty and that has knocked out their interplanetary comms, going: “Dude, you know you could have included that particular point – in – the Constitution, you know that ‘instruction manual’ you were talking about, rather than buried somewhere in one of your multitudinous essays (in which you do go on, you know).”
What is written – in that document that you necessarily haven’t seen – very much is written from a constant boots-on-the-regolith view as to the situation likely faced by the first humans to permanently settle another world.
* * *
Now, if, without seeing a – single – word of the actual project itself, you already have come to a conclusion about what I’m doing, well, that is your prerogative.
And once you actually have seen it, you very well may hold to that conclusion. And/or many other pejorative assessments.
(Writing a proposed constitution just inherently is that kind of a project. If there’s one person out of eight plus billion that agrees with everything in it – that – will be astounding.)
And then you can send those folks up there with the Book of Job or the Art of War.
But – as to instead me – I wasn’t wringing my hands with my above comments going basically “I’m lost with this project; I don’t know what to look at; I don’t know if my work is on point, what to do, what to do.”
It was just an . . . update.
I’m mostly deferential here as most of the discussion here is way outside my bailiwick.
And in any event I tend to speak in an informal, mostly Southern United States manner of address.
But, in – my – field, no one – ever – has accused me of lacking confidence.
Or of an inability to do a large project and do it well, and do it on point.
Quite frankly with good reason, as I’m damned good at what I do.
Not infallible, no one is.
But if anyone got a subtext of indecision, uncertainty or lack of confidence in my update that most definitely was not something that I was seeking to convey.
I confess that I have fired off posts on X on rare occasion where I hadn’t first read the underlying article, especially if it’s pay-walled. But I do try to avoid yielding to the temptation of doing that.
And I write a lot of preliminary draft comments for here that I never actually post on Centauri Dreams. Either because I still haven’t first read the underlying paper, and/or I don’t otherwise have the time to fully vet what were off-the-cuff thoughts. Particularly if I thereby would be critiquing something that I actually hadn’t read – worse yet in a field not my own – if I posted what I had in initial draft.
A salutary practice which I commend highly to others.
It was . . . just . . . an update.