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The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was not promoted by Ian Rose 10:03, 3 August 2013 (UTC) [1].[reply]

Circumstellar habitable zone

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Circumstellar habitable zone (edit | talk | history | protect | delete | links | watch | logs | views)

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Nominator(s): Wer900 • talk 20:02, 24 June 2013 (UTC)[reply]

This article has been comprehensively and completely rewritten, and the rewrite itself has been modified to a significant extent, since the last time it was assessed. I feel that after having rewriting the article it is far stronger than the C-class work that it was assessed to be before. The article has seen little major change day-to-day since the period immediately after the rewrite, and uses the latest literature in order to produce a high-quality, authoritative work. For those reasons, I feel that "Circumstellar habitable zone" should be a featured article. Wer900 • talk 20:02, 24 June 2013 (UTC)[reply]

Review by Jamesx12345

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This was on my list of articles to look at, so I feel I can make some (hopefully useful) comments.
  • The first sentence is perhaps a bit too technical. In no way demeaning the intellect of some readers, the word "commensurate" is a bit long for a first sentence. Perhaps there is a simpler way of saying that it is where liquid water is found?
    • done. Replaced with "sufficient", even though that doesn't get across the whole concept (a gas giant in the CHZ will not have liquid water at its core, but exotic ices). Wer900 • talk 00:56, 25 June 2013 (UTC)[reply]
  • Same with "inferred"
    • done. Replaced with "[t]he bounds of the CHZ are calculated"
  • "Most are more massive than the Earth" make explicit the differences in composition?
  • "the CHZ concept has been broadly challenged as a primary criterion for life." Nuff said. I defy you to find an 11-year-old doing a class project on aliens that will explain that sentence to you.
    • Removed "broadly", hopefully that should help (and make clear that the scientific consensus is very much in favor of the CHZ being the most likely location for life, or at least intelligent life). Wer900 • talk 00:56, 25 June 2013 (UTC)[reply]
  • "the basic conditions for water-dependent life may be found even in interstellar space" I was under the impression that there are flecks of comet and suchlike but nothing really conducive to life. It's the interstellar space I don't get - that would probably have to be referenced

Good opening - it is nicely written, but perhaps a bit denser than it needs to be. Looking at FAs like Big Bang and Sun, they tend to assume nothing, but there are some more advanced concepts as well. Jamesx12345 (talk) 21:24, 24 June 2013 (UTC)[reply]

  • History looks fine. Could mention be made of earlier hypotheses regarding extraterrestrial life? It has been a question for at least a few hundred years, so perhaps its lack of consideration is worth a mention.
  • "various planetary scientists" looks like a weasel word. (If "various" is given in the reference perhaps that could be made clearer?)
    • done. Replaced with "several".
  • "put ηe at 0.48" 48% is a bit less intimidating (in brackets maybe?)
  • "Extrasolar extrapolation" I think people will either understand the maths or not - the inverse square law is pretty elementary, so you could just say "quarter luminosity, half the distance," with a link somewhere to the inverse-square law. I'm not sure if that needs a ref as it could be WP:OR. (Not that I contest it!)
    • The relevance of the inverse-square law and the complications to its use are already mentioned, and as you said, it's pretty elementary, so I don't think that such a level of explanation is necessary. Wer900 • talk 01:30, 25 June 2013 (UTC)[reply]
  • "numerous roadblocks to a perfect extrasolar extrapolation of the circumstellar habitable zone concept" a bit verbose again - sorry.
Further comments
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  • "However, stellar evolution is at play with red dwarf system habitability as well, reducing the wild fluctuations in luminosity so planets are more likely to have life." I can't say I am entirely clear what this sentence means - it seems to be that the first and second sentences in this paragraph contradict each other, and then the final one clarifies the point. I think the use of "is at play" is causing the confusion - if replaced with a direct statement saying that red dwarves stabilise as they age, it would help with comprehension.
  • "could render water unable to form a liquid" - could you be more specific and say it would sublime? (Or come very close)
    • It could go in both the solid and the gas directions based on which direction the temperature and pressure fluctuate, so I think that added specificity is unnecessary. Wer900 • talk 18:58, 25 June 2013 (UTC)[reply]
  • "55 Cancri f was discovered within 55 Cancri A's circumstellar habitable zone" - this could be embellished to "55 Cancri f was discovered within the circumstellar habitable zone of its host star 55 Cancri A" for those not familiar with naming conventions.
  • "While conditions on this massive and dense planet are not conducive to the formation of water or for that matter biological life as we know it, the potential exists for a system of moons to be orbiting the planet and thus transiting through this zone and being conducive for biological development." This would most likely need to be sourced.
  • "The planet is currently listed as unconfirmed by the Extrasolar Planets Encyclopedia." I'm not clear about this reference - I can't find any suggestion of a planet g in the database.
  • "preclude the planet from being habitable" does this merit further explanation? Sounds interesting.
    • done. Nothing too interesting, just it was kicked outside the HZ. This article is not the place
  • "Many argue" - another weasel word (although it may be correct to use it here)
  • The last section is not as strong as the rest of the article. Aside from the obvious tag, it seems to be based too largely on a single source, and under-referenced in general. As an aside, no mention is made here (except in the image caption) of carbon chauvinism or the potential for alternative biochemistries.

Jamesx12345 (talk) 19:12, 25 June 2013 (UTC)[reply]

Image review

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  • Please look at grammar in image captions
  • File:Habitable_zone_-_HZ.png: source image has been deleted as incompatible with Commons' licensing
    • done. Replaced with another image compatible with our licensing; the image indicated was deleted as text and another image later convey the same information; plus, it doesn't look good to have a non-professional, technical image at the beginning of the article. Wer900 • talk 18:08, 25 June 2013 (UTC)[reply]
  • File:Estimated_extent_of_the_Solar_Systems_habitable_zone.png: what is the source for the information conveyed by this diagram?
  • File:UpsilonAndromedae_D_moons.jpg: not sure about this - it's claimed as own work, but compare for example the current front-page image here.
    • done. A bit of poking around shows that the image predates the Basel Peace Office by over a year, so they took it from us rather than the other way around. I could see nothing indicating it is not own work. Wer900 • talk 18:08, 25 June 2013 (UTC)[reply]
  • File:Phot-15b-09-fullres.jpg: source link is dead. Nikkimaria (talk) 13:52, 25 June 2013 (UTC)[reply]

Recent changes

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  • Most recent changes to the page are minor, but I think that the ultraviolet habitable zone needs further explanation. I am concerned that an "ultraviolet habitable zone" is a bit arbitrary, given that it depends on the atmosphere of the planet and the type of organism considered. Jamesx12345 (talk) 20:18, 26 June 2013 (UTC)[reply]
    • The liquid water CHZ is also "arbitrary" in the same way, but based on general climate models for different masses of planets it *can* be predicted. the UVCHZ is the same. Anyway, I will clarify that section, as the UVCHZ is just the region where a forming planet can escape photoevaporation of itself or its atmosphere while it is forming and after. Wer900 • talk 17:00, 27 June 2013 (UTC)[reply]

Casliber comments

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Reading through - queries below Cas Liber (talk · contribs) 19:43, 27 June 2013 (UTC)[reply]

  • In June, 2011, two additional habitable zone candidates around Gliese 667 through Bayesian Re-analysis of radial velocity signals—Super-Earths Gliese 667 Cd and Gliese 667 Ce. - this sentence has no verb - also can it be appended onto one of the preceding paras?
  • Such a concept was the idea behind Stephen H. Dole's 1964 study. - sentence sorta just sits there and isn't clear it refers to the following sentence. A semicolon between might be a good link between the two.
  • At present, you have the last para of the History section and then a criticism section covering similar or same material - these would be best combined - in either location. Also title criticism is somewhat generic, as it is more like proposing alternative avenues to explore.

Otherwise, little to complain about - will take another look and have a think. Cas Liber (talk · contribs) 20:05, 27 June 2013 (UTC)[reply]

Sasata comments

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Oppose for now. Interesting material, but the text needs to be swept for MoS compliance, typos, and more wikilinks would be helpful to the average reader. Please consider the following suggestions, questions, and comments for possible article improvement: (p.s. per the FAC instructions, avoid using templates "(such as {{done}}, {{not done}} ... as they slow down the page load time and lead to errors in the FAC archives" Sasata (talk) 05:41, 30 June 2013 (UTC)[reply]

  • please audit the article for duplicate wikilinks; there's a handy tool to help
  • consider changing various "noun" + ing constructions (search for "being")
  • ""Liquid Water Belt" which described" which=>that (audit throughout; which generally follows a comma)
  • "first introduced the term" underlined probably unnecessary
  • "The theory of habitable zones was further developed in 1964 by Stephen H. Dole in his book Habitable Planets for Man, in which he covered the circumstellar habitable zone itself as well as various other determinants of planetary habitability, eventually estimating the number of habitable planets in the Milky Way to be about 600 million." I'd suggest breaking this sentence in two. Why "eventually"? Does this mean he came to the conclusion by the end of the book, or later, after the publication of the book?
  • "At the same time …" Really? Or would "Around the same time" be more appropriate?
  • "In 1993, astronomer James Kasting" why is the profession of this blue-linked fellow given (his article calls him a geoscientist, BTW), but not that of the (twice!) red-linked Stephen H. Dole?
  • pipe link heavier elements?
  • "More recently, several planetary scientists have criticized" Should reword "recently" per WP:RELTIME
  • link ammonia; link methane on 1st occurrence
  • "would not cause a boiling away of liquid water." -> perhaps switch to active voice, like "would not cause liquid water to boil away."
  • "A 2013 study by Ravi Kumar Kopparapu put ηe at 0.48" ηe is not explained until later in the article
  • "95-180 billion" use endash for number ranges
  • "In 2011, Seth Borenstein in 2011 concluded" fix
  • "based on observations from the Kepler mission" the link should probably go to ‪Kepler (spacecraft)‬ rather than Johannes Kepler (I see it's linked correctly later in the article)
  • "concluding that about "1.4 to 2.7 percent" of all sun-like stars" why does the percentage range have to be in quotes? Later in the same sentence, "expected to have earthlike planets "within the habitable zones of their stars"," why does this have to be quoted? Could it be replaced with simply "within the CHZ"?
  • the final sentence of the 1st paragraph of "Solar System estimates" needs a citation
  • "and global warming inducing atmospheres" hyphen between warming-inducing? Also, link global warming, glaciation, albedo, cloud albedo (maybe fit a link to Ice-albedo feedback somewhere too?), relative humidity
  • "This estimate has often been cited by subsequent publications." source?
  • "combining high obliquity and orbital eccentricity" link to axial tilt and orbital eccentricity (I see the latter is linked twice later, but should be linked at 1st occurrence)
  • "Applies to planet with" -> planets
  • consider linking luminosity at the 2nd occurrence (would be far away from the 1st link in the lead)
  • 'Various complicating factors, though, including the individual characteristics of stars themselves, mean that extrasolar extrapolation of the CHZ concept is more complex." source?
  • "Some scientists argue that the concept of a circumstellar habitable zone is actually limited to stars"
  • link binary system; does the existence of a binary systems always extend the CHZ when compared to a single-star planetary system?
  • "Michael Hart proposed that only main-sequence stars of spectral class K0 or brighter could possess habitable zones, an idea which has been extended in modern times" that last clause makes me wonder when Hart proposed his theory
  • link red-dwarf habitable zone, tidal heating, climate model, space weather, magnetosphere, stellar evolution, helium, metabolism
  • "Given that this new equilibrium lasts for about 1 Gyr," rather than have the unknowing reader sent to Byr, how about including parenthetically (1 billion years)
  • "The origin of water on Earth is still unknown, possible sources include" think a semicolon works better than a comma here
  • "put a habitable moon so close to astar that" -> a star?
  • "Later study revealed temperatures analogous to Venus ruling out any potential for liquid water." comma after Venus?
  • consider putting a {{nowrap}} template around 70 Virginis b, 16 Cygni Bb and other similar names to avoid unsightly line breaks
  • "Gliese 876 b, discovered in 1998, and Gliese 876 c, discovered in 2001, are both gas giants discovered in the habitable zone" too many "discovered"
  • "around Gliese 876. although" fix punctuation
  • link gas giant
  • check ending punctuation in figure captions per WP:Caption
  • "existence has recently been put into doubt" when is recently? "The planet is currently listed as unconfirmed" as of when?
  • "and colleagues" is a friendlier version of "et al." that is probably more appropriate in the article text for a general encyclopaedic audience
  • "the Earth Similarity Index (ESI)" don't need to define acronyms that aren't used later in the text
  • "located 49 ly from Earth" here the abbreviated form of light years is used (and linked again), but it's spelled out in previous and later instances
  • "The discovery of two planets orbiting in the habitable zone of Kepler-62, by the Kepler team was announced on April 19, 2013." something's wrong with the grammar/flow here
  • "Many argue that an orbit" sounds weaselly
  • the Drake equation is linked, but perhaps Drake should be linked as well; link search for extraterrestrial intelligence
  • this article refers to "Wow! reply", but our article on the subject calls it Wow! signal
  • "The concept of a habitable zone is criticized by Ian Stewart and Jack Cohen in their book Evolving the Alien" please give year of publication of this book for context
  • per WP:SEEALSO, several of the "See also" links should be removed, as they are already linked in the article
  • please consider use a flexible, browser-dependent column width setting for the references (like colwidth=30em); it's currently hard-coded to be 4 columns, which looks rather thin on my monitor setting (and for many others, I suspect)
  • the references need to be tweaked for consistent presentation; please audit the following:
  • display of author names (see "James Kasting" vs. "Strughold, Hubertus" vs. "Hart, M. H."); note that sometimes author names are abbreviated, even though their full names are available from the cited source
  • journal article titles should be consistently either title case or sentence case; be careful to ensure that if sentence case is used, to capitalize terms that require it (like "Kepler M-dwarfs")
  • page range format: compare "1602–6" vs. "1279–1297"
  • why two "et al."s in ref #82?
  • need to be consistent in how many author names are given before et al.; compare ref #85 vs. ref#112 vs. ref#126
  • ref #123 consists of only a Russian-language title … how about an author, indication of language, accessdate, publisher, etc.?
  • page numbers for ref#128?
Response
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I apologize for the mistakes I made wholeheartedly. Some of the mistakes were inserted subsequent to the rewrite by well-meaning authors who did not clean up after themselves, and as the FAC nominator it is my job to clean up after those changes. However, I stand by statements that appear to be weaselly. The ambiguity is deliberate; unlike in the case of anthropogenic global warming, it is not possible to cite any study that qualifies these terms further. The only thing that is evident immediately is that many scientists believe life as we know it can emerge on worlds with Europa with the ingredients for life coming from elsewhere, with a few scientists believing in the existence of radically different biochemistry with different life requirements. I will fix the other mistakes that you identified with regards to the MOS. Wer900 • talk 20:02, 30 June 2013 (UTC)[reply]

I fixed many of the errors in the article with AWB, including doubled wikilinks. However, I think that it is important to retain links to important subjects at the end, just to centralize them after a reading of the article. Wer900 • talk 03:50, 1 July 2013 (UTC)[reply]

Comments by Nergaal

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  • "an support liquid water at the surface" I would also add: and therefore is the location with the highest probability of encountering habitats where life is sustainable (in essence that is the main point of the CMZ term)
  • "To many" what? Scientists? Astronomers? Average folks?
  • "has been estimated to be anywhere from 500 million[4] to over 150 billion." in the Milky Way? Observable Universe?
  • "numerous planets have now been discovered in the CHZ" this is a bit skewed. when was the first planet discovered in this zone? (first confirmed planet was only about 15 years ago)
  • "to greatly outnumber planets": terrestrial planets or also super-Jupiters?
  • "In subsequent decades" does this refer to the first reference in the 50s?
  • the intro image is terrible. if you try to click and zoom on it you cannot read anything
  • the intro doesn't address clearly the location of the zone for a single star or a binary, or ternary one
  • I think the "Goldilocks zone" term can be mentioned in the intro since it might be more common to some non-experts
  • for some reason I think that the third paragraph is a bit overly represented (it discusses the stuff in a small section at the end and the last paragraph in the first section). I want to say that this could be trimmed slightly and moved to the correct sections (for example the radioactive decay is not discussed in the actual article)
  • I think the determination section could receive a better representation in the intro; for example to a casual reader it would be useful to explain that the CMZ in the SS has earth close to the center, and extends until close to Venus, and may extend past Mars and Ceres.
  • "While the entire orbits of the Moon" isn't the Moon completely within the chz?
  • submitted papers???? wtf? this is a FAC, so a peer-approved paper is a minimum requirement; these guys might be right but until reviewers give ok they can't even be mentioned in a note of a FA.
  • intro could also say that a star 4 times of luminous as the Sun would have the CMZ located at twice the distance (or 4 times less luminous, half the distance)
  • stellar evolution: how soon will the Earth fall out of the habitable zone?
  • "15 millibars" what is the pressure on Mars? what planet in the SS has such a low ground pressure?
  • "could render water unable to form a liquid" huh? this sounds like BS or an over-simplification. liquid water can exist at any pressure given a certain temperature. what constrains does the statement include?
  • "the Hill radius of the planet so that they are not pulled out of orbit of their host planet" not sure how this works. you mean a satellite of the moon would not be habitable?
  • "cannot have habitable moons" i would stay away from such clear-cut statements, and replace them with "are highly unlikely to have habitable moons"
  • " to astar" space
  • "the fraction of stars with planets in the CHZ" does this refer to main-sequence stars only? or all stars? including binary systems?
  • "about "1.4 to 2.7 percent" of" is this the latest number? and how many planets does this mean for the MW?
  • " planets were discovered. " add year; "ne of the first discoveries was 70 Virginis b," add year again
  • " to themselves possess " rephrase
I implemented most of these recommendations and those of Sasata, but I think the submitted articles are okay, especially considering that they are written by reputable scientists with long histories of publication in planetary astrophysics, and that the criteria they specify are not used in any other place by the article. Wer900 • talk 19:57, 2 July 2013 (UTC)[reply]
  • fix the "Gas giant planets in the habitable zone" link
  • "KOI-1686.01" should also be discussed
  • " the first super-Earth" put in the parenthesis how much bigger than earth is this
  • mention the Gliese 667 C system, and finish the super-earth section with a statement along the lines that the number of reports of such planets is rabidly growing in the last several years (i.e. so to leave the reader the impression that the section may look very different in a couple of months)
  • please put a mini-definition of a waterhole in parenthesis (region region in the radio spectrum not absorbed by atmospheric water)

I really like the article otherwise. Nergaal (talk) 06:53, 1 July 2013 (UTC)[reply]

Mostly done, although I had added another image which was later removed. Wer900 • talk 21:54, 4 July 2013 (UTC)[reply]

Oppose! Umh yeah, after a month I come back to see that most of my comments I gave after spending a few hours reviewing the article have not been fixed. Nergaal (talk) 01:19, 3 August 2013 (UTC)[reply]

Comments by Cryptic C62

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  • "planetary-mass objects with sufficient atmospheric pressure can support liquid water at the surface." Shouldn't this say "at their surfaces"?
  • "To many scientists, studying objects in the CHZ appears to be the best way to estimate the scope of life in the universe and locate extraterrestrial life." Let's try to rewrite this without weaselling, eh? "Studying objects in the CHZ may be the best way to estimate the scope of life in the universe and locate extraterrestrial life."
  • Ref 20 "Rare earth" needs page numbers, either in the citation or using {{rp}}
  • Ref 130 "Evolving the Alien": see above
  • Why are there so many external links? Some of these look like they should be citations, which violates WP:EL: "Most external links should present different details from citations." I strongly suggest cutting this list down. The larger it is, the less useful it becomes.

Meep. --Cryptic C62 · Talk 18:05, 24 July 2013 (UTC)[reply]

    • Done, except for page numbers and external links. I am still waiting for page numbers (I do not have those particular books), and as for external links the link list has already been reduced dramatically, and we have a particularly long article here. Another reviewer has stated his reluctance to trim more links. Wer900 • talk 23:21, 26 July 2013 (UTC)[reply]

Comments by Hamiltonstone

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  • The main section "Determination of the circumstellar habitable zone" begins with this: "Whether a body is in the circumstellar habitable zone of its host star is dependent on both the radius of the planet's orbit (for natural satellites, the host planet's orbit) and the mass of the body itself." Shouldn't this general introductory sentence specify three key variables rather than just these two? Isn't the third key variable the energy output of the star? hamiltonstone (talk) 13:05, 28 July 2013 (UTC)[reply]
  • There is a whole table of at times quite variable estimates regarding the solar habital zone, but there should be some discussion of these in the text. The table needs to be referred to by the text.
  • Having just explained that there is a range of estimate regarding the zone, and tabulated those, there's something wrong with the next sectin having this: "For example, while the Solar System has a circumstellar habitable zone centered at 1.34 AU from the Sun..." We don't really know this with such precision - it is one (perhaps leading) estimate. Suggest it be rewritten as "For example, if the Solar System..." etc hamiltonstone (talk) 13:11, 28 July 2013 (UTC)[reply]
  • The article suddenly moves up a level in its ideas at this point: "On the other end of the spectral scale, Michael Hart proposed that only main-sequence stars of spectral class K0 or brighter could possess habitable zones, an idea which has been extended in modern times with the concept of a tidal locking radius for red dwarfs. Within this radius, which is coincidental with the red-dwarf habitable zone, it has been suggested that the volcanism caused by tidal heating could cause a "tidal Venus" planet with high temperatures and no ability to support life". I'm afraid a lay person isn't going to follow the rapid evolution of the argument here. Needs an extra sentence or two and the logic needs explaining. First of all, it seemed to me that Hart's general idea expressed in the sentence (that the range of stars that can have CHZs can be narrowed) is superficially contradicted by the idea that a star so different from the sun as a red dwarf could have a hab zone. The two sentences at least should be disconnected. Then you need to explain why a tidal locking radius is relevant (or even what a tidal locking radius is. I don't immediately associate tidal locking with tidal heating, so i thought I had encountered a second non-sequitur in the para. Then, why is this radius concidental with the hab zone?? And why would it be a "tidal Venus"? Why not a "tidal Earth"? And if it cannot support life, as the sentence concludes, why is this even in an article about CHZs? As you can see, this para lost me! :-) hamiltonstone (talk) 13:19, 28 July 2013 (UTC)[reply]
  • Some of the explanatino appears to lie in a later section, so some of the issues could be addressed with a reordering.
  • "Moving a moon closer to a host planet to maintain its orbit would create tidal heating so intense as to eliminate any prospects of habitability". This makes it sound as though one is planning a massive engineering project. Try "A moon close enough to a host planet to avoid this problem, however, would experience tidal heating so intense as to eliminate any prospects of habitability".

Delegate comments -- after remaining open almost six weeks there appear to be too many unaddressed comments for consensus to be achieved any time soon, so I'll be archiving this shortly; pls review and/or action all comments before considering another nomination here, which in any case cannot take place before the usual two-week break per FAC instructions Cheers, Ian Rose (talk) 01:34, 3 August 2013 (UTC)[reply]

The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
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