Misplaced Pages

This is an archive of past discussions about K2-18b. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

An unpublished arXiv preprint as a source

An unpublished arXiv preprint does not satisfy WP:RS and should not be used as a reference, especially for such an important scientific discovery. Nsk92 (talk) 02:11, 12 September 2019 (UTC)

I replaced the reference to this preprint with a published reference in ScienceNews discussing both studies, and moved the preprint ref to external links. Nsk92 (talk) 02:43, 12 September 2019 (UTC)

As long as have at least one source that notes it, this solution should be fine. Probably worth the check in 6 months or so to see where its publishing status is at. --Masem (t) 04:08, 12 September 2019 (UTC)

We should not use an unpublished primary source as a reference, especially for such an important discovery, when multiple published reliable secondary sources are aviailable. Nsk92 (talk) 10:12, 12 September 2019 (UTC)

Probably shouldn't get excited about a preprint, and then relying on a secondary source based on the preprint (and possibly the Nature paper, but who can tell). Given that there is a peer-reviewed paper as well as the preprint, both making essentially the same claims, quoting both shouldn't be a problem. Then use the secondary sources to establish notability, and rely on the primary sources for "facts". No point in copying a copy, doubling the risk of misinterpretation or a simple transcribing mistake. Lithopsian (talk) 14:01, 12 September 2019 (UTC)

Distance of 111ly is overly precise

The Misplaced Pages article says the distance is 111 light years away, referencing a BBC article.

The original paper in Nature Astronomy says it is "34 pc" away, or 34 parsecs. 34 pc = 110.8932 light years. With only 2 digits of precision, the range 33.5-34.5 pc is 109.2624 to 112.523963 light years. It seems more appropriate therefore to use "about 110 light years" as the distance, which also has 2 significant digits.

This is what TechCrunch does at https://techcrunch.com/2019/09/11/hubble-spots-liquid-water-on-a-super-earth-110-light-years-away/ and NBC News at https://www.nbcnews.com/mach/science/strange-alien-world-found-have-water-vapor-possibly-rain-clouds-ncna1052486 . — Preceding unsigned comment added by 83.255.22.84 (talk) 19:38, 11 September 2019 (UTC)

How about "about 111" which is closer to the estimates cited (have added 'about' to the number). Randy Kryn (talk) 19:49, 11 September 2019 (UTC)

The star K2-18 has a Gaia DR2 parallax of 26.2686±0.0546 mas. That's pretty precise. The {{starbox astrometry}} template would render this as 124.2±0.3 ly. Cloutier et al. (2019) state 38.025±0.079 pc for the Gaia DR2 distance. Lithopsian (talk) 20:02, 11 September 2019 (UTC)

I also see the NASA exoplanet database has 38.068 pc but I can't see where they are getting that number. --Masem (t) 02:24, 12 September 2019 (UTC)

That comes from the parallax given in the same database, which is the Gaia DR2 parallax (with a rather pointless number of decimal places). A more interesting question might be why the published paper gives a slightly different value. 38.025±0.079 pc is very very close to the value given in Bailer-Jones et al. (2018), but not exactly. The most likely distance for a star based on a parallax with a finite margin of error is not the inverse of the parallax, as shown at the exoplanet database (and used in the starbox calculation). Either way, the distance of ~111 light years (34 pc) quoted in popular articles is woefully obsolete, somewhat sad that it the Nature paper using it. Lithopsian (talk) 13:49, 12 September 2019 (UTC)

As related, I am assuming it is more common that these papers all publish that distance in parsec so that when other sources (like mainstream) take rounded numbers and covert that to light-years, that's where the "error" is being introduced, right? So we should start from the best peer-reviewed published number in parsecs and then convert to ly for reader convenience. --Masem (t) 13:57, 12 September 2019 (UTC)

Also, the "Cloutier2019" article does go on to explain this all so I've included that (including the original 34 pc) so that we can account for older data. --Masem (t) 14:15, 12 September 2019 (UTC)

Mini-Neptune

It may qualify as a super Earth solely by mass, but by composition (ice/gas mix) it is better described as a mini-Neptune. It has been described as a mini-Neptune by reliable sources, some are:

• "Laura Kreidberg, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said that K2-18b might be better described as a “mini-Neptune” than a “super Earth.” Extensive research with computer models suggests that, at 1.6 to 1.8 times the mass of Earth, planets tend to become huge and gaseous, rather than rocky."
• Ars Technica: "The planet, K2-18b, is certainly not habitable by us, as it's a mini-Neptune that may not have any solid surface and is likely to have a hydrogen/helium-rich atmosphere."
• NASA: " resembling a small version of Neptune."
• The Verge: " a type of world often referred to as a mini-Neptune".

Cheers, Rowan Forest (talk) 13:47, 13 September 2019 (UTC)

I could have also sworn one of the journal reports we have also compared it to Neptune (due to being H2, He, and ices). I know another paper discussed the possibility of it having a more rocky core and did their models based on both assumptions, with the mini-Neptune having the more statistically significant result. The thing is that "Super-Earth" is the technical qualification based on it size, but its clear that in the field "super-Earth" does not mean it has a rocky core. It would be fair to say, after discussing its likely composition, it has been compared to a "mini-Neptune". --Masem (t) 14:07, 13 September 2019 (UTC)

It can be classified according to mass and according to composition. Lets mention both. Cheers, Rowan Forest (talk) 14:11, 13 September 2019 (UTC)

Checked the scholarly sources, and its discovery called it a mini-Neptune, but all papers since (likely with the improved numbers from Spitzer) use super-Earth. I did add mini-Neptune language though (since we have that article). --Masem (t) 14:26, 13 September 2019 (UTC)

Thanks. Just as it was done at K2-288Bb time ago. Cheers, Rowan Forest (talk) 14:28, 13 September 2019 (UTC)

xkcd

Today's xkcd is apt: https://xkcd.com/2202/ Fdfexoex (talk) 18:57, 13 September 2019 (UTC)

20 to 50% water vapor?

In the article there is a line about the atmosphere being 20 to 50% water vapor that I cannot find confirmation of in the sources listed after the sentence. It might be contained in the nature article (which I can't access). I find this claim unlikely. Did I miss it in the sources after the sentence, or is it in another source? Rockphed (talk) 19:08, 13 September 2019 (UTC)

It's the Nature article, and that's why the ArXiv link is provided, the preprint is available. --Masem (t) 19:19, 13 September 2019 (UTC)

The nature article is also available on the arxiv at https://arxiv.org/abs/1909.05218 and on page 6 it mentions the 20 to 50% as one possible model with another model having as low as 0.01% so basically the wikipedia article is misrepresenting the source. Fdfexoex (talk) 19:22, 13 September 2019 (UTC)

I added the additional range as it depends what atmospherical model they use. --Masem (t) 19:30, 13 September 2019 (UTC)

Composition?

The article currently says "This classifies the planet as a super-Earth, though its size makes it unlikely to be composed of rocky iron and silicates, and more apt to be formed of hydrogen, helium, and astronomical ice", and cites this to Rogers 2015. I have just taken a look at Rogers. Not being a scientist in the field, I could not properly follow the article, but my best reading of it was that a better wording would be "unlikely to be formed solely of rocky iron and silicates, and more likely to include hydrogen, helium, and ice". that is, I could not get from Rogers that K2-18b was likely to be ONLY H/He and volatiles. Could someone more knowledgeable in the field take a look and see what they think? hamiltonstone (talk) 12:43, 13 September 2019 (UTC)

Rogers has an analysis of exoplanets baesd on their sizes (relative to earth's size) and what is known about their compositions, and generally states that of the catalog of super-Earth (any planet from 1 to 10 times the mass of earth) that is larger than 1.5 the mass of earth is unlikely to have a rocky (iron/silicate core - what we know from our solar system) core, and instead are more likely to be H2/He with other gases. Papers on K2-18b refer to Rogers to re-assert this, since K2-18b is ~8 x the mass of Earth. --Masem (t) 14:10, 13 September 2019 (UTC)

And to be specific, Montet 2015 is that paper I was thinking of. --Masem (t)

Yes, but I am seeing a difference between the core and the composition of the whole planet. Just checking the article language is right. hamiltonstone (talk) 00:26, 14 September 2019 (UTC)

The way I understand the terms: the data is separating the atmosphere from the core (I may be wrong). They're looking at what light passes through the planet for the composition of the atmosphere, as light will not pass through the core - which could be a rocky core, or an extremely dense (by pressure) H2/He/ice core. The whole composition of atmosphere + core would be something different. --Masem (t) 00:52, 14 September 2019 (UTC)

"Habitable Zone" + water does not mean habitable

This article is sort of clickbait in that a) about 8x the mass of earth also means 8x the gravity. No human could survive for long on the surface. b) There are a lot of other things that define "habitable" besides proximity to a star. Water is probably present on any planet in a "habitable" zone whether detected or not. Obviously there is more to learn about this planet, but I have issue with the term "habitable" when not put in proper context - this planet is NOT habitable (at least to humans) based on mass/gravity alone. It also may be much too hot (much like Venus) with an orbital period of only 33 days. Liquid water is not indicated - only vapor. 2600:6C48:7006:200:B056:6066:1296:EF0B (talk) 00:33, 13 September 2019 (UTC)

All uses of the word "habitable" is with "habitable zone", exception for one place where it is explained that this does not likely mean the planet is habitable (that's wehre a lot of press is click-baity). Also, the star is a red dwarf, so actually no the surface temperature is not believed to be that hot. --Masem (t) 01:03, 13 September 2019 (UTC)

"8x the mass of earth also means 8x the gravity". True, at the same distance. However, what we're really interested in is not gravity at some arbitrary fixed distance, but surface gravity, i.e. the g-force on the surface of K2-18b, which is only ${\displaystyle M_{factor}/R_{factor}^{2}=8.63/2.71^{2}=1.18}$ times that of Earth. --46.242.12.78 (talk) 02:03, 13 September 2019 (UTC)

Ok, I accept your equation that perhaps the gravity is not an issue (for humans), assuming it has a solid surface close to its measured diameter. Or an atmosphere that is not crushing. "Assuming" a lot in this here article though. "Habitable" term is my hangup. I'd bet my life savings that nobody will prove it to be habitable to any life form in my lifetime... 2600:6C48:7006:200:B056:6066:1296:EF0B (talk) 01:50, 17 September 2019 (UTC)

It is an unfortunately situation today that astronomers chose the term "habitable zone" back, as non-astronomers are probably looking at that term in the press and reading it as "a zone that is habitable" rather than the astronomic definition which is very specific. We here on WP are definitely not trying to mislead to claim this planet is habitable. --Masem (t) 04:08, 17 September 2019 (UTC)

No human would want to be anywhere near that close to a red dwarf. You'd be alternately fried and irradiated, or frozen. "Habitable zone" and being habitable to some life form are two different things. Theories about the life at the border of day and night on such planets are just speculation. 104.169.37.72 (talk) 04:13, 13 September 2019 (UTC)

We can do a better job highlighting that "habitable zone" only refers to the potential to have liquid water at the surface, but in this ice/gas planet, apparently there is no potential for that, just vapor. Also, "habitable" in this context refers to microbial life, often extremophiles. Cheers, Rowan Forest (talk) 13:54, 13 September 2019 (UTC)

Whatever happened to "Goldilocks Zone"? "Habitable" zone carries too much baggage. 2600:6C48:7006:200:B056:6066:1296:EF0B (talk) 00:56, 17 September 2019 (UTC)

Goldilocks Zone redirects to Circumstellar habitable zone. Rowan Forest (talk) 00:58, 17 September 2019 (UTC)

Does anyone know something that can be . . . habited?

There is no such thing as a "habitable zone". Nothing "habits" a space; rather, it inhabits it. What astronomers and astrophysicists mean and should say is: "inhabitable zone".

Merriam-Webster lists only one verbal meaning for "habit": "to clothe or dress". Merriam-Webster Dictionary, s. v. "Habit" It lists multiple verbal synonyms as well: Synonyms: Verb apparel, array, attire, bedeck, caparison, clothe, costume, deck (out), do up, dress, dress up, enrobe, garb, garment, get up, gown, invest, rig (out), robe, suit, tog (up or out), toilet, vesture

Does any one of the above fit? I fail to see how . . . unless, you mean it's the area in which planets put on their clothes.Mwidunn (talk) 13:24, 17 September 2019 (UTC)mwidunn

Understand that "habitable zone" is a term of art from the astronomical side of things, WP is not making this up. (Also, I would not be using a dictionary to try to counter scientific arguments. "Habitation" is the root word you want, which is where "Habitable" extends from, not from "habit". --Masem (t) 14:01, 17 September 2019 (UTC)

Merriam-Webster seems pretty lacking, then; Samuel Johnson, in 1755, offered "HABITABLE. adj. Capable of being dwelt in; capable of sustaining human creatures" with cites from Francis Bacon, John Donne and John Dryden. It's been in use by the best authors of Modern English for most of its 500 year existence.--Prosfilaes (talk) 07:48, 18 September 2019 (UTC)

GAN review

This review is transcluded from Talk:K2-18b/GA2. The edit link for this section can be used to add comments to the review.

Reviewer: InterstellarGamer12321 (talk · contribs) 08:48, 18 June 2023 (UTC)

GA review (see here for what the criteria are, and here for what they are not)

The article looks like it is in good shape. It is quite long so I will need time to have an in-depth look at it before giving my comments. InterstellarGamer12321 (talk | contribs) 08:48, 18 June 2023 (UTC)

1. It is reasonably well written.

   a. (prose, spelling, and grammar):

   b. (MoS for lead, layout, word choice, fiction, and lists):

2. It is factually accurate and verifiable.

   a. (reference section):

   b. (citations to reliable sources):

   c. (OR):

   d. (copyvio and plagiarism):

3. It is broad in its coverage.

   a. (major aspects):

   b. (focused):

4. It follows the neutral point of view policy.

   Fair representation without bias:

5. It is stable.

   No edit wars, etc.:

6. It is illustrated by images and other media, where possible and appropriate.

   a. (images are tagged and non-free content have non-free use rationales):

   b. (appropriate use with suitable captions):

7. Overall:

   Pass/fail:

(Criteria marked are unassessed)

Initial comments

• Are you sure that all of the concerns in Talk:K2-18b/GA1 have been addressed? If not, please fix those issues before continuing.

  Yes, I am pretty sure. Jo-Jo Eumerus (talk) 12:15, 18 June 2023 (UTC)

• Spend some time copyediting and improving the prose, because not all of it currently adheres to WP:MOS.

  Got to need some examples, sorry. There are some things that are deliberately written as they are, because the alternatives would be misleading, overlong etc. Jo-Jo Eumerus (talk) 12:15, 18 June 2023 (UTC)

  The main issues are with footnotes appearing before punctuation (WP:REFPUNC). Other issues are minor.

  Now, my understanding has been that explanatory notes can be put after the word they explain, while citations ought to go after punctuation. Jo-Jo Eumerus (talk) 17:58, 18 June 2023 (UTC)

  Note b comes after punctuation, but notes c and d come before it. It looks best if they all come after the punctuation.

  Standardized. Jo-Jo Eumerus (talk) 18:08, 19 June 2023 (UTC)

• While I understand that there are no images of this exoplanet, please confirm that there are no more images worthy of being included in the article.

  I don't think there is one, really. Jo-Jo Eumerus (talk) 12:15, 18 June 2023 (UTC)

• All inline citations in the article are scientific papers. While they are reliable, I would also recommend adding a few references to reliable news sources about the exoplanet for more well-rounded coverage, although you do not need to do this if you have a reason.

  I prefer not to use such sources - half of what they say is already said by the academic ones, the other half seems often to be of questionable reliability. And people use news sources in one article as a rationale for adding them elsewhere even when they don't belong. Jo-Jo Eumerus (talk) 17:58, 18 June 2023 (UTC)

More comments

• In the Physical properties section, does the term radius valley need to be redlinked and italicised?
• In the Discovery and research history section, does the term Hycean planet need quotation marks?

  I think so, yes, these are technical terms that need to be singled out. Jo-Jo Eumerus (talk) 18:08, 19 June 2023 (UTC)

• The title of the article and mentions in the lead call the exoplanet K2-18b. However, there are several in the body of the article that call it K2-18 b. Change them all to K2-18b for consistency.

  Done. Jo-Jo Eumerus (talk) 19:12, 20 June 2023 (UTC)

• In the Atmosphere and climate section, it talks about "hazes". Should this be changed to haze?

  Not sure why this would be necessary. Jo-Jo Eumerus (talk) 19:12, 20 June 2023 (UTC)

• Are all of the error margins necessary in the body of the article? They break the flow of the article.

  Yes, people often take the numbers while ignoring the qualifiers otherwise. Jo-Jo Eumerus (talk) 19:12, 20 June 2023 (UTC)

Prose comments

The prose quality is now the only thing stopping the article from becoming GA, but it needs a decent bit of work. Comments below:

• It orbits its star in 33 days, from Earth it can be seen passing in front of the star. Needs a conjunction or should be split into two separate sentences.

  Hmm, they are sort of related. I don't like the many short sentences thing. Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• intermediary radii cannot hold their atmospheres against the tendency of their own energy output and of the stellar radiation to drive atmospheric escape: the "of" before stellar radiation is redundant here.

  Done. Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• This distinction between planet populations is known as the radius valley and planets on its smaller side are known as Super-Earths and those larger as Sub-Neptunes. Specify what the distinction is and use a better term than "its smaller side".

  Specified, although one would think that folks would understand it means "radius". Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• the planet may have taken a few million years to assemble. I feel that there is a better word to use than assemble here.

  Not that comes to mind, sorry. Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• which might destabilize the planet's climate by preventing material flows between the core and the ocean. Specify what "material flows" is.

  This something I was unsure myself; what is the best word to define chemical/material exchanges? Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• its existence cannot be inferred or ruled out solely from the mass-radius of a planet. Is "mass-radius" a legitimate term or should it be split into "mass and radius"?

  Changed. Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• The existence of a liquid ocean is improbable at K2-18b, the water under the envelope is more likely in a supercritical state. Feels better to use a semi-colon or conjunction rather than just a comma.

  Done. Jo-Jo Eumerus (talk) 18:04, 22 June 2023 (UTC)

• has an atmosphere consisting of hydrogen: what percentage of the atmosphere is hydrogen?

  From what I can see, we don't know yet. H2-He ratios are seldom of astrobiological interest. Jo-Jo Eumerus (talk) 15:20, 23 June 2023 (UTC)

• Similar to the above point, it might also be worth adding the percentage of methane if possible.

  We don't know them with any precision. Jo-Jo Eumerus (talk) 15:20, 23 June 2023 (UTC)

• water clouds, the only species likely to form at K2-18b, is conflicting. Specify that it means cloud species - I did not understand what it meant for some time.

  Done. Jo-Jo Eumerus (talk) 15:20, 23 June 2023 (UTC)

• Apart from water ammonium chloride, sodium sulfide, potassium chloride and zinc sulfide can form clouds in the atmosphere of K2-18b, depending on its properties. Add a comma after water and change "its" to "the planet's".

  Done. Jo-Jo Eumerus (talk) 15:20, 23 June 2023 (UTC)

• there is not a substantial temperature gradient between poles and equator: add a "the" before poles.

  I dunno, it may suggest that it's between both poles, rather than pole-to-equator. Jo-Jo Eumerus (talk) 19:37, 24 June 2023 (UTC)

• They concluded that the photochemistry should not be able to completely remove ammonia from the outer atmosphere: Create a wikilink from photochemistry or specify what it is.

  Linked. Jo-Jo Eumerus (talk) 19:37, 24 June 2023 (UTC)

• while the water layers might have temperatures and pressures suitable for the development of life. Is this referring to the water layers of the atmosphere? Specify if it is.

  Done. Jo-Jo Eumerus (talk) 19:37, 24 June 2023 (UTC)

• after a reasonable amount of observations. Change "amount" to "number". Also, can it be specified how many observations are needed?

  Done. Jo-Jo Eumerus (talk) 19:37, 24 June 2023 (UTC)

• and drew a lot of discussion: From where? By whom? Specify and expand on this.

  The sauce unfortunately is not very specific on this. Jo-Jo Eumerus (talk) 18:16, 26 June 2023 (UTC)

  Are there any other sources you can use? InterstellarGamer12321 (talk | contribs) 06:47, 27 June 2023 (UTC)

  No, we aren't at the level of knowledge yet where folks would discuss the significance of a finding in detail, beyond noting that it is significant. Jo-Jo Eumerus (talk) 18:05, 27 June 2023 (UTC)

• a type of planet which combines abundant water with a hydrogen envelope: is combines the best word to use here. Saying "a type of planet that has both abundant liquid water and a hydrogen envelope" might be better.

  Yes, that's in. Jo-Jo Eumerus (talk) 18:16, 26 June 2023 (UTC)

I am going to pass the article imminently. Well done! InterstellarGamer12321 (talk | contribs) 17:53, 29 June 2023 (UTC)

Setting up archival. Jo-Jo Eumerus (talk) 17:48, 11 September 2023 (UTC)

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b

https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b Rps (talk) 15:51, 11 September 2023 (UTC)

Interesting. If nobody comes before this, I'll be adding it on my end-of-year pass. Jo-Jo Eumerus (talk) 17:48, 11 September 2023 (UTC)

Article misrepresents Benneke et al. and D. Blain et al.

The following passage is incorrect, "Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood. There is evidence that there are distinct planetary populations with Earth-like and Neptune-like radii, presumably because planets with intermediary radii cannot hold their atmospheres against the tendency of their own energy output and the stellar radiation to drive atmospheric escape and thus end up with a thin atmosphere or none at all. This distinction between planet populations is known as the radius valley and planets on its smaller-radius side are known as Super-Earths and those larger as Sub-Neptunes."

This is a misrepresentation of Benneke et al. The cited page, page 2, is specifically referring to a lack of observational data on the atmospheres of planets with masses between Earth and Neptune. It is NOT claiming that there is a lack of planets of those sizes, as super earths are the most common size for known exoplanets. I'm not sure how much it adds to the article in the first place. I'm removing it, but maybe someone could rewrite it so that it is accurate.

I noticed another problem where the article says, "It probably has little internal heat left". This is not what page 15 of D. Blain et al. says. To quote it directly, "it seems unlikely that the residual heat of formation could be sufficient to explain a high internal temperature." It is comparing different models, some of which require a high internal temperature. The paper is saying that K2-18b likely does not have a high internal temperature. Thus, the above passage from the article is a misrepresentation.

It looks like one person is responsible for a large portion of this article, the same person who made the above errors. I'm concerned this person has littered the article with additional errors. Most of the article may need to be completely redone anyway in light of the new paper by Madhusudhan et al. 24.233.97.244 (talk) 20:38, 11 September 2023 (UTC)

User:Jo-Jo_Eumerus is responsible for both errors, here and here. These are the kinds of errors that reveal a lack of understanding of the source material as well as the field more broadly. In the first instance, anyone who is knowledgeable about the field knows that super earths are extremely common, so it's hard to excuse. The source is very clearly talking about atmospheric composition. The second instance is also not excusable. Like the first example, it is grossly misunderstanding the source material. It's also something that would be easily caught by somebody with even a basic knowledge of planetary formation and thermo-dynamics. K2-18b is much younger than the Earth and also much larger. It could not have possibly cooled down from its formation yet to the point where it has "little internal heat left".

Someone who makes these sorts of basic errors should not be editing wiki pages based on what they've read in dense, highly technical papers that they do not have the slightest grasp on. In the event that they claim they were just "typos" or something, they've made 70 separate edits. They would have caught the mistakes if they were equipped to.

The majority of his edits reference very technical papers such that it will be quite difficult to fact check everything, especially considering the volume of edits this user has made. It is my view that all of their edits should be reverted. The recent paper by Madhusudhan et al. is going to lead to transformative changes to this article. As of yet no edits have been made regarding it, so it would be the perfect time to roll back the clock on this article.

24.233.97.244 (talk) 22:03, 11 September 2023 (UTC)

Yeah, I did write these and I dispute that "Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood" means "claiming that there is a lack of planets of those sizes". As for the rest, which you also removed:

• Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood. sounds adequately supported by Very little is currently known about the bulk and atmospheric compositions of planets with masses between those of Earth and Neptune. These planets have no analogs in the solar system, although I wonder if a less similar formulation is warranted.
• There is evidence that there are distinct planetary populations with Earth-like and Neptune-like radii, presumably because planets with intermediary radii cannot hold their atmospheres against the tendency of their own energy output and the stellar radiation to drive atmospheric escape seems reasonably supported by Refined population studies of the radius distribution of sub-Neptune-sized planets have revealed a significant drop in the planet occurrence rates between near 1.5–2.0 R⊕ (Fulton et al. 2017; Fulton & Petigura 2018). Photoevaporation (Lopez & Fortney 2013; Owen & Wu 2013; Lopez & Rice 2018) and core-powered mass loss (Schlichting 2018) are two theories that can reproduce this observed drop in the occurrence rate. According to photoevaporation models, the most highly irradiated super-Earths are expected to have primarily rocky compositions and relatively small radii, while less irradiated super-Earths are able to retain a modest (few percent in mass) primordial hydrogen-rich atmosphere that inflates their observed radii to values greater than 2.0 R⊕.
• and thus end up with a thin atmosphere or none at all is from By essentially using the mass and radius of the planets, it has been well-established that planets with low masses (<2 M⊕) must primarily be made up of iron and silicates, and generally with a thin atmosphere. and the second follows from the fact that many non-Sun stars emit more high-energy radiation and thus may strip away atmospheres entirely even on Earth-mass planets. Fair, the latter part probably can be sourced better, though.
• This distinction between planet populations is known as the radius valley and planets on its smaller-radius side are known as Super-Earths and those larger as Sub-Neptunes. is from Exoplanets that fall between Earth’s (1 R⊕) and Neptune’s (≈4 R⊕) radius are generally classified as either super-Earths or sub-Neptunes depending on whether their radii lie below or above the radius valley at 1.5–2.0 R⊕ (Fulton et al.2017), respectively
• It probably has little internal heat left and tidal heating is unlikely. The first part I'll grant was a misread, but the second from In that configura- tion, a lot of orbital energy can indeed be dissipated, but only in the innermost planet8, that is, K2-18 c. Thus, there should be no tidal heating on K2-18b is sound.
• If it exists, internal heating may increase temperatures at large depths, but is unlikely to significantly affect the surface temperature. figure 6 does illustrate that internal heat only affects temperature below about 1-10 bar depth.

So no, I don't agree with these removals save one, let alone with a total revert of my additions. Jo-Jo Eumerus (talk) 07:47, 12 September 2023 (UTC)

"Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood. sounds adequately supported by Very little is currently known about the bulk and atmospheric compositions of planets with masses between those of Earth and Neptune. These planets have no analogs in the solar system, although I wonder if a less similar formulation is warranted."

• I never said that exact sentence was incorrect. I removed it, because it was used in such a way that it bolstered subsequent incorrect claims. I didn't think it made much sense to keep in and of itself. It may still have a place in the article, however.

"There is evidence that there are distinct planetary populations with Earth-like and Neptune-like radii, presumably because planets with intermediary radii cannot hold their atmospheres against the tendency of their own energy output and the stellar radiation to drive atmospheric escape seems reasonably supported by Refined population studies of the radius distribution of sub-Neptune-sized planets have revealed a significant drop in the planet occurrence rates between near 1.5–2.0 R⊕

This distinction between planet populations is known as the radius valley and planets on its smaller-radius side are known as Super-Earths and those larger as Sub-Neptunes. is from Exoplanets that fall between Earth’s (1 R⊕) and Neptune’s (≈4 R⊕) radius are generally classified as either super-Earths or sub-Neptunes depending on whether their radii lie below or above the radius valley at 1.5–2.0 R⊕ (Fulton et al.2017), respectively"

• The way you had worded it in the article implied that there is a lack of a prevalence of planets between the sizes of Earth and Neptune. That's not true. There is a drop of occurrence rates, that would otherwise be expected, at 1.5-2 Earth radii. The range of radii between Earth and Neptune is much greater than that, ranging from 1 R⊕ to 4 R⊕. When you wrote that atmospheric loss is an explanation for it, you are conflating the explanation for why there is a lack of expected planets at 1.5-2R⊕ with why there are distinct populations with Earth and Neptune-like radii. The paper specifically says there is a lack of understanding of bulk and atmospheric compositions of the masses of exoplanets between Earth and Neptune. It is plainly not referring to a radius gap if it's talking about exoplanet groups of a specific of mass. Then it says "most atmospheric studies resulted in nondetections due to the prevalence of high-altitude clouds" as an explanation for why. It is saying the particular atmospheric compositions of planets between the masses of Earth and Neptune, present during those observations, made atmospheric study difficult. NOT that there is a lack of atmospheres to be detected in that range. You are conflating two different things.

"It probably has little internal heat left and tidal heating is unlikely. The first part I'll grant was a misread, but the second from In that configura- tion, a lot of orbital energy can indeed be dissipated, but only in the innermost planet8, that is, K2-18 c. Thus, there should be no tidal heating on K2-18b is sound."

• Yes, tidal heating is unlikely according to the original paper, but the only reason it was in the article was to back up your false claim. So there's no reason for it to be present otherwise.

24.233.97.244 (talk) 14:17, 12 September 2023 (UTC)

Size in this article (and from seeing other Misplaced Pages articles in astronomy) refers to radius, not mass. I also don't see how one could read " It is NOT claiming that there is a lack of planets of those sizes, as super earths are the most common size for known exoplanets." and not conclude that you were talking about that sentence. And the other paper with photoevaporation flat out says that the drop in occurrence rate is due to atmosphere loss, not observation biases.

Your removals were excessive, too. Since this article discusses the planet in general, it ought to mention that it is not expected to feature tidal heating. And since it is often used as an example of a sub-Neptune, a discussion of the radius gap is apropos as well. Jo-Jo Eumerus (talk) 14:57, 12 September 2023 (UTC)

"I also don't see how one could read " It is NOT claiming that there is a lack of planets of those sizes, as super earths are the most common size for known exoplanets." and not conclude that you were talking about that sentence.

• If you are referring to the sentence, "Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood." You got that from the same part of the very same paper that you interpreted incorrectly and pulled the rest of the removed paragraph from. I removed it because I didn't think it made much sense there by itself, since the whole paragraph it was a part of was removed. I agree that this single sentence is correct and could be added back to the article somewhere. So let's move on from it and focus on what is the actual contention.

"Size in this article (and from seeing other Misplaced Pages articles in astronomy) refers to radius, not mass."

"And the other paper with photoevaporation flat out says that the drop in occurrence rate is due to atmosphere loss, not observation biases."

• To reiterate once more, it specifically is referring to 1.5-2 Earth radii exoplanets. It has nothing to do with there being distinct Earth and Neptune sized exoplanets. You misconstrued the hypothesis for why there is a lack of exoplanets between 1.5-2 Earth radii as an explanation for there being distinct Neptune and Earth-sized exoplanets. The way it was worded suggested that there is a lack of planets between those radii. It is very plain to see. If you were familiar enough with the field to be interpreting these papers, you would know the radii of Neptune offhand and wouldn't have made this error. Let me quote the paper; "Very little is currently known about the bulk and atmospheric compositions of planets with masses between those of Earth and Neptune. These planets have no analogs in the solar system, and aside from the recent atmospheric detection for GJ 3470b, most atmospheric studies resulted in nondetections due to the prevalence of high-altitude clouds." Here it is decidedly referring to planets in mass between Earth and Neptune, NOT radius. Afterwards it discusses the specific subclass of those planets with radii between 1.5 and 2 Earths. These planets are a subset of planets that generally fall between 1 and 4 Earth masses.

"Your removals were excessive, too. Since this article discusses the planet in general, it ought to mention that it is not expected to feature tidal heating."

• I wouldn't have to explain this to you if you were qualified to interpret these papers. You admitted you were wrong about the internal temperature aspect. It wasn't just a misreading, it simply does not say anything like how you interpreted it. A planet of this mass and age would be nowhere near cooling off. This isn't a mistake an informed person makes. The part of the paper you pulled from was breaking down different simulated scenarios. One of those scenarios would require a high internal temperature that could not be explained from observational data. The part about tidal heating not being possible was specifically in reference to the paper detailing why a certain scenario wasn't likely, because it would require tidal heating that could not be explained. And you misinterpreted that to mean that it must not have a hot core at all. It's not like these were two separate facts, the second sentence was only included to explain the first one. Alone it doesn't make sense to include.

"And since it is often used as an example of a sub-Neptune, a discussion of the radius gap is apropos as well."

• Not if we're going to misinterpret what the radius valley even is.

24.233.97.244 (talk) 16:02, 12 September 2023 (UTC)

It's not a matter of explaining, it is flat out incorrect to remove the tidal heating claim because a separately sourced, distinct claim next to it was incorrect. The source does say that evaporation leads to the existence of two different planet types and to the rarity of intermediate-radius planets. Perhaps you have an alternative text explaining this (with sources) that can be put in the article? Jo-Jo Eumerus (talk) 16:26, 12 September 2023 (UTC)

"It's not a matter of explaining, it is flat out incorrect to remove the tidal heating claim because a separately sourced, distinct claim next to it was incorrect."

• Let's review the sentences; "It probably has little internal heat left and tidal heating is unlikely. If it exists, internal heating may increase temperatures at large depths, but is unlikely to significantly affect the surface temperature." The second sentence is directly following on the unsubstantiated claims of the first sentence. They are inexorably tied together. The second sentence is factually correct, but by itself does not add to the article. According to D. Blain et al. 2021, based on observational data, there's no evidence to support a mechanism for internal heating. As you know, everything in a scientific paper isn't necessarily going to be relevant to a Misplaced Pages article. It's postulating a hypothetical situation that as yet we have no reason to believe exists. We could come up with hypotheticals all day, but unless there is evidence behind it, it should not be added to the article.

"The source does say that evaporation leads to the existence of two different planet types and to the rarity of intermediate-radius planets."

• Yes, two different groups that are entirely distinct from the Earth-Neptune radii spectrum. The two groups cited in the paper are, "the most highly irradiated super-Earths are expected to have primarily rocky compositions and relatively small radii," And the next group, "while less irradiated super-Earths are able to retain a modest (few percent in mass) primordial hydrogen-rich atmosphere that inflates their observed radii to values greater than 2.0 R⊕" The specific planet types fall on either side of the radius valley. NOT on either side of the Earth-Neptune spectrum. As stated previously, Neptune is approximately 4 Earth radii. They are two entirely different groups. Please do not edit based on scientific papers that you do not have a robust understanding of.

24.233.97.244 (talk) 17:32, 12 September 2023 (UTC)

I don't think that this supports the notion that the Earth-Neptune divide is distinct from the sides of the radius valley, and nothing about the other literature on the radius valley I've heard argues so either. Also, please don't quote each text you are replying to, it makes it hard to read your posts. Jo-Jo Eumerus (talk) 17:46, 12 September 2023 (UTC)

"I don't think that this supports the notion that the Earth-Neptune divide is distinct from the sides of the radius valley"

• It is absolutely distinct. I've demonstrated that conclusively. The radius valley is 1.5R⊕ to 2.0R⊕. Earth and Neptune are 1R⊕ and 4R⊕ respectively.

24.233.97.244 (talk) 17:53, 12 September 2023 (UTC)

That demonstrates that the planets form two distinct groups, with intermediate sizes being less common ("radius valley"). It does not explain what is wrong with Planets with compositions intermediate between that of Earth and Neptune have no analogues in the Solar System and are thus poorly understood. There is evidence that there are distinct planetary populations with Earth-like and Neptune-like radii, presumably because planets with intermediary radii cannot hold their atmospheres against the tendency of their own energy output and the stellar radiation to drive atmospheric escape and thus end up with a thin atmosphere or none at all. This distinction between planet populations is known as the radius valley and planets on its smaller-radius side are known as Super-Earths and those larger as Sub-Neptunes. It's Neptune-like and Earth-like radii, we aren't limiting the discussion to planets that are only exactly as wide as Neptune or Earth. Jo-Jo Eumerus (talk) 16:27, 13 September 2023 (UTC)

I'm not going to make a new heading for this, and I'm not going to read all the other points.

I just came to say I'm noticing misqoutes and weasel words in the article after checking 1 source:

"It is estimated that 80% of all M dwarf stars have planets in their habitable zones,"

this is not in the reference, what it actually says is

"Results from the Kepler mission indicate that the occurrence rate of small planets

(<3 R⊕) in the habitable zone of nearby low-mass stars may be as high as 80%."

First of all it is a far more sweeping statement if you drop the Kepler mission context,

because as it says that survey was of nearby low-mass stars, not the universe.

Secondly it doesn't either say all planet types, as implied by only using the term planet,

but rather is specified that the near 80% is in reference to small planets;

you cannot paraphrase the quote and leave out the word small.

Thirdly according to the Star article "Low mass star (including the Sun), with a mass between 0.5 M☉ and ~2.25 M☉"

is what is referred to, not the more specific "all M dwarf stars."

Can the writers here stop twisting what is said in the references to say what they want it to say?

24.78.228.96 (talk) 21:07, 22 September 2023 (UTC)

Dunno what source you are reading, but It is estimated that 80% of all M dwarf stars have planets in their habitable zones, is sourced to Benneke et al. 2019 says Kepler showed that as much as 80% of M dwarfs host small planets (<3R⊕) in the habitable zone which also says nothing about "nearby"; evidently scientists are comfortable with assuming that it can be generalized to the universe. From other sources it seems like it can be generalized even beyond Kepler. Also, I am pretty certain there is no such thing as a non-planet "small planet". Jo-Jo Eumerus (talk) 06:34, 23 September 2023 (UTC)

Is water confirmed or not?

This source says that apparently the presence of water is not confirmed. I've taken the Madhusudhan 2023 source as evidence that it isn't. Jo-Jo Eumerus (talk) 17:03, 7 December 2023 (UTC)

Lyman alpha transit

The article currently treats it as questionable, but this source seems to take it for granted. Jo-Jo Eumerus (talk) 17:03, 7 December 2023 (UTC)

Online radio interview

I kinda wonder if this addition is giving one radio interview WP:UNDUE weight. A quick Googling doesn't show any indication that it drew particular attention. Jo-Jo Eumerus (talk) 07:43, 14 January 2024 (UTC)

My issue isn’t with undue weight as much as it is with duplicating content. The Planetary Society is pretty notable, but the information presented appears to duplicate what is already in the current version. Viriditas (talk) 20:02, 15 January 2024 (UTC)

It is a very handy multimedia interview for those who are not good at reading and like to listen when they want. Yes, it isn't a particularly weighty interview, although it was among the first few that my search engine came up with when I started searching. I think taking out the sentence: "From the transcription: "K2-18 b spectra James Webb Space Telescope's (JWST) NIRISS and NIRSpec instruments detected methane and carbon dioxide in the atmosphere of exoplanet K2-18 b, along with potential traces of dimethyl sulfide (DMS), a substance that is created on Earth by living creatures" would go along way to stop any duplication - the all important observations by MIRI aren't mentioned anywhere and nor is the lack of water in the atmosphere. Those MIRI observations that happen this January (perhaps already have) will give more robust results.

As for the spectra, I have uploaded it to Wiki Commons under a Creative Commons Attribution 4.0 International license as explained here https://esawebb.org/copyright/. It was downloaded from here: https://esawebb.org/images/weic2321b/ and is high quality. NASA images are free to upload and I have done over a hundred. As long as the authors are credited, it is fit for purpose: the article is bereft of images and a picture is worth a thousand words... Richard Nowell (talk) 15:21, 16 January 2024 (UTC)

If the content can be used, I would merge it into the respective sections. There’s no need to talk about the podcast and we don’t need to crystal ball future results. Just expand what we already have. Viriditas (talk) 18:03, 16 January 2024 (UTC)

I am not sure the podcast has a lot of information that the article doesn't already contain. The spectra are OK, though. Jo-Jo Eumerus (talk) 09:24, 18 January 2024 (UTC)

I have uploaded the image of JWST spectra with credits. I think it is a useful and attractive image that adds clarity to that section and can also be used outside WP. Richard Nowell (talk) 15:19, 17 January 2024 (UTC)

Viriditas mentioned this discussion to me on my talkpage. I am fine with the podcast as a source, for sure. Not sure the podcast as a podcast necessarily deserves its own paragraph, but the JWST observations generally ought to be discussed. jps (talk) 23:23, 18 January 2024 (UTC)

Comment on latest edit

This one, where I have recast AstroChara's edit so that it matches the used citation format, without leaving unsourced sentences or unnecessary lead section. I'll do a further edit to readd some things. Jo-Jo Eumerus (talk) 09:35, 9 March 2024 (UTC)

Hey,

I've read through your edits, and I noticed that you have reinstated the original leading section, where it emphasizes only one of the many possible models of K2-18 b, and contains a mention of 'similar surface conditions' although we know this planet does not have that, being a subneptunian planet with hydrogen atmosphere. I've tried to amend this section to be less biased by adding mentions of the proposed alternative models, which are equally as valid, if not moreso. What is the reason you decided to remove these additions and not readding them back?

Also, the rationale for moving the magma ocean model to Possible ocean is that it is directly relevant to the plausibility of the the ocean, with the magma ocean model competing with the water ocean model, providing alternative explanations for the observation. I find its placement in the Possible ocean section to be good because it gives the sense of uncertainty to the water ocean model, which is the case in the field. AstroChara (talk) 18:53, 9 March 2024 (UTC)

What exactly was "unsourced" or "unnecessary"? I have read over the edits AstroChara made, and they were all appropriately cited with up-to date sources. Your edit to re-add some things did not include any of the details from newer publications. Xiphosura 23:36, 9 March 2024 (UTC)

Except the sentence " is also capable of acting as a sink for ammonia, as well as a source for carbon dioxide." which had become detached from

the source. Also, we generally do not put citations in the lead (WP:LEADCITE). Fair point of the magma or water thing; I've added that back in. Also moved the magma ocean bit to the ocean section; was that what you recommended? JoJo Eumerus mobile (main talk) 11:58, 10 March 2024 (UTC)

Not sure why you didn't just readd what I wrote, remove the sources from the lead, and alert me to add source to the ammonia section. I will restore my edit with some modifications as you recommended, and add a mention of the gas-rich mini-Neptune model (which is still missing from the lead section) to the text. AstroChara (talk) 17:54, 10 March 2024 (UTC)

The link you provided to leadcite states "Although the presence of citations in the lead is neither required in every article nor prohibited in any article, there is no exception to citation requirements specific to leads." And specifically, "balance the desire to avoid redundant citations in the lead with the desire to aid readers in locating sources for challengeable material."

The different models pertaining to the structure of the planet if nothing else should readily be "challengeable", i.e. when newer data and publications come out, it should be updated accordingly. Nowhere does it state "generally do not put citations in the lead", quite the opposite. There are plenty of lede citations that you left completely untouched elsewhere. As for that, thank you for re-adding in the more recent proposal, that is what I was planning to do; though I also must ask what the purpose of completely wiping multiple well-sourced sentences was if your only problem was a single sentence becoming detached from a citation. It seems rather overzealous a response, did you not check first? If you have just modifications to add, wiping it all to trickle a lot of the already present information back in later seems quite redundant.

In any case, I'm glad this seems to be mostly resolved. Xiphosura 03:09, 11 March 2024 (UTC)

Generally, "challengeable" does require more than some disagreement around sources. Especially on a topic like an exoplanet, where there will be lots of disagreement on how to interpret scant data. You are liable to either duplicate the rest of the article, or to inadvertently cherry-pick, if you add sources there. WRT rewrite, I think a section like However, a subsequent work finds that a magma ocean is also capable of dissolving ammonia and explaining the observation results, while another paper suggests that a gas-rich mini-Neptune model is capable of replicating the observed amount of methane and carbon dioxide, while a liquid water ocean model requires the presence of a biosphere in order to produce sufficient amount of methane is unnecessarily wordy, especially the "However, a subsequent work finds that" and "while another paper suggests that". I wonder if this block should say that the lack of ammonia is a problem for the gas-rich mini-Neptune model. Jo-Jo Eumerus (talk) 09:17, 11 March 2024 (UTC)

The Wogan 2024 paper finds agreement between their mini-Neptune model and the lack of ammonia detection, so I believe we don’t need such a mention. AstroChara (talk) 01:15, 13 March 2024 (UTC)

Why is the Radius Valley mentioned

The paragraph mentioning the Radius Valley in the Physical Properties section is going to lead to confusion. At 2.6 Earth radii, K2-18 b falls significantly outside of it. It would be easy to mistakenly come away from reading that paragraph with the impression that this planet's radius is inside of the Radius Valley because otherwise why would it be included? The Radius Valley is not relevant to this article. 65.175.252.60 (talk) 03:46, 20 May 2024 (UTC)

I think it works as an explanation of the Super-Earth/Sub-Neptune distinction, but maybe it could be moved to a footnote. Jo-Jo Eumerus (talk) 07:08, 21 May 2024 (UTC)

New addition

Are we sure that "However, on May 20th 2024, The Astrophysical Journal published a reevaluation of the initial readings which indicate that no biosignatures were ever detected on K2-18b" is interpreting the source correctly? At first glance, it seems to do but syfy references the original paper and it doesn't seem to say such a thing at all. Jo-Jo Eumerus (talk) 07:06, 21 May 2024 (UTC)

@Jo-Jo Eumerus: to answer your question honestly, no I am not sure - however, this is why I think it is important to frame the sentences as "these are what the scientists are claiming" instead of putting it as a straight fact. you know what I mean?--Osh33m (talk) 15:27, 21 May 2024 (UTC)

If the original paper does not literally say "no biosignatures were detected at all" then perhaps the source really is just clickbaiting and dismissing the initial findings. --Osh33m (talk) 15:28, 21 May 2024 (UTC)

@Osh33m: Here's a publically accessible version of the paper. Also pinging @AstroChara and Xiphosura: Jo-Jo Eumerus (talk) 16:15, 21 May 2024 (UTC)

It is interpreting the listed source correctly, but SYFY itself seems to have misinterpreted the paper. It isn't even a re-evaluation of the data, it is an attempt to model an atmosphere like K2-18b's to see at what point the DMS becomes clearly detectable, and suggests other signatures to check for. Nothing is explicitly ruled out, it just puts that detection boundary at 20x Earth's biogenic sulfur flux and even goes so far as to say this is "within the plausible range of surface biomass density." I'll rewrite that section and cite the paper directly.

Honestly more concerning to me though is the prior claim of "50% chance of finding life". While it's certainly a legitimate quote from a qualified professional, I fear it will be taken far too seriously as a prediction. That's the sort of wild claim people tend to run with all too eagerly should they find it in WP articles. Xiphosura 05:35, 23 May 2024 (UTC)

Rewrote your addition a bit, as it was mentioning some IMO unnecessary details or things that fit better in other sections. I wouldn't be averse to removing that claim. That section has a bit of a problem with becoming a list of every attention-getting mention of K2-18b in the media, regardless of WP:Due weight. Jo-Jo Eumerus (talk) 08:37, 23 May 2024 (UTC)

I also agree with the suggestion to remove the interview passage. AstroChara (talk) 19:05, 25 May 2024 (UTC)

Can't we leave some excerpt from the interview? It seems counterproductive to remove any trace of there being that interview entirely given the fact that it exists and offers insight to the ongoing research. --Osh33m (talk) 21:49, 28 May 2024 (UTC)

Well, have third-party heavy-weight sources discussed that interview? Jo-Jo Eumerus (talk) 07:11, 29 May 2024 (UTC)

I am sure that they have, but when the discussion here came about removing the interview, it was never about the fact that third party sources weren't added, only about the veracious insinuation of the claim in the interview itself. --Osh33m (talk) 13:09, 29 May 2024 (UTC)

Sure, but that doesn't mean that the WP:Undue concern is invalid. Jo-Jo Eumerus (talk) 06:11, 30 May 2024 (UTC)

Your inaccurate edits of this article border on vandalism and yet you still hang around here as if your opinion has any weight. 65.175.252.60 (talk) 18:20, 1 June 2024 (UTC)