Talk:Proxima Centauri b/GA2

GA Review
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Reviewer: CheChe (talk · contribs) 11:01, 25 February 2017 (UTC)

Hello again, CheChe here, I'm planning to review this article and will probably finished by the end of the weekend. I've got high hopes for this nomination after it came so close last time. Thanks goes to MartinZ for notifying me of this renomination, I hope I don't disappoint!

Oh, before I forget, I would like to ask permission to make minor copyedits while I'm reviewing. Would that be ok? —♫CheChe♫ talk 11:01, 25 February 2017 (UTC)
 * Yes, it would be OK. —MartinZ (talk) 11:05, 25 February 2017 (UTC)


 * CheChe, I believe I've fixed all of the issues. —MartinZ (talk) 14:00, 26 February 2017 (UTC)

Great, fantastic work. We're almost there, but there are still a few issues:
 * On the 'triple star system' issue: I agree that this does not need to be covered in depth here, but I think there's still a problem. The fact that the star is in a triple star system is not obvious, and as a reader, it's jarring to suddenly find this out in the middle of a sentence that is explaining the metallicity of the star. Fixing this would be a simple as adding "... which is in a triple star system" to the first sentence (or something similar).
 * ✅. —MartinZ (talk) 15:48, 26 February 2017 (UTC)
 * About the signal being measured in days: I understand that the source used days. My specific issue with this sentence is that it isn't clear what it is trying to tell the reader. The significance of the length of a signal has not been explained, and the reader is left confused as a result.
 * Should we just remove the sentence? —MartinZ (talk) 15:53, 26 February 2017 (UTC)
 * Actually yes, that seems like the best course of action. —♫CheChe♫ talk 16:08, 26 February 2017 (UTC)

Other than those I think we're actually done now. I was worried about the selfsource because it seemed like an exceptional claim, but as I noted, others seem to have supported this claim so I think it's ok. Sorry to have put you through all that other referencing stuff too: your responses where very thorough and that's appreciated a lot. —♫CheChe♫ talk 15:20, 26 February 2017 (UTC)

Seems like everything is in order. I'm going to do one quick re-read to make sure everything still makes sense, but then it should be a pass. Thanks for everything. —♫CheChe♫ talk 16:08, 26 February 2017 (UTC)

Okey-dokey, it's a pass. Well done, MartinZ, for helping with this last push. Happy editing! —♫CheChe♫ talk 16:19, 26 February 2017 (UTC)

Summary
This article is generally well written and informative. The clarity of the writing has significantly improved since last review, but a number of notable issues remain in this department. Other than that the only significant issue is with verifiability. Beyond minor issues with the referencing format, there are several sources that do not seem to support the content. Unfortunately this means the article cannot be passed at this time.

As with the previous nomination, I think this problems should be relatively simple to solve. For these reasons I am putting this nomination on hold for now.

Writing and compliance with Manual of Style
 The prose is usually clear and concise (I have made some copyedits), but is let down by the exploration section. There is a lot of repeated information in this section. It could probably be condensed into just two paragraphs, which would make it clearer and more concise. The following prose issues also need to be addressed:
 * ✅. —MartinZ (talk) 11:02, 26 February 2017 (UTC)

 There are potential issues with the lead section. The lead is meant to be an overview of the important information on the article. Given this, it seems odd that there is no mention of physical characteristics, or anything relating to the sections on future observations. Less pressingly, there seem to be an unnecessary number of references for this uncontroversial piece of information: In August 2016, the European Southern Observatory announced the discovery of the planet. Since this is repeat/summery of information that appears later in the article, it would be ok to drop all the references.
 * (Characteristics 1): Although the meaning is clear to me, 'maximum doppler shift' is inaccurate: there is only one measured doppler shift. This probably to be rephrased.
 * ✅. —MartinZ (talk) 20:25, 25 February 2017 (UTC)
 * (Characteristics 2): Triple star system? This should have probably been mentioned explicitly at some point prior to this.
 * ❌—it's covered more in‐depth on "Alpha Centauri" and "Proxima Centauri"—the article is about the planet, not the star(s), after all. —MartinZ (talk) 18:51, 25 February 2017 (UTC)
 * (Characteristics 4): This whole paragraph is just one sentence. Please break it up into more manageable chunks if possible.
 * ✅. —MartinZ (talk) 17:45, 25 February 2017 (UTC)
 * (Habitability 1): 'vaguely' is not a very specific word. Consider choosing something more concrete.
 * ✅. —MartinZ (talk) 17:57, 25 February 2017 (UTC)
 * (Habitability 1): Does the last sentence belong here? It doesn't seem to tell us much new.
 * ✅. —MartinZ (talk) 17:55, 25 February 2017 (UTC)
 * (Habitability 3): Consider fixing the clarify ([how?]) tag. Contribute to what?
 * ✅. —MartinZ (talk) 19:11, 25 February 2017 (UTC)
 * (Habitability 4): ...of the planet facing the star or diurnally in the equatorial belt (3:2 resonance rotation) . Please refactor this sentence not to use brackets. It's very confusing as it stands.
 * ✅. —MartinZ (talk) 17:49, 25 February 2017 (UTC)
 * (Habitability 5): This paragraph seems out of place. Is it possible it could be incorporated into one of the other paragraphs.
 * ✅. —MartinZ (talk) 17:28, 25 February 2017 (UTC)
 * (Discovery 2): Why is the signal is measured in days? This probably needs to be clearer.
 * ❌—the source measured the signal in days. —MartinZ (talk) 17:21, 25 February 2017 (UTC)
 * (Exploration 3): This paragraph doesn't seem to belong here. Is it needed at all?
 * ✅. —MartinZ (talk) 16:23, 25 February 2017 (UTC)
 * —removed the references; I'll fix the rest of the lead later. —MartinZ (talk) 15:44, 25 February 2017 (UTC)
 * I have now fixed the lead—there should be two sentences about the planets physical characteristics; also, a sentence already exists for "Future observations": "According to Guillem Anglada‐Escudé, its proximity to Earth offers an opportunity for robotic exploration of the planet with the Starshot project or, at least, 'in the coming centuries'." —MartinZ (talk) 13:56, 26 February 2017 (UTC)

 There is room for improvement in terms of layout. I feel like it would be best to merge the observations exploration sections, and rename it 'future observations' or something. At the very least the observations section needs to be renamed.
 * ✅. —MartinZ (talk) 16:55, 25 February 2017 (UTC)

 There is an issue a phrase that should be avoided. In (Exploration 1), 'recent' is a relative time phrase, please try to replace this with something that won't automatically make itself out-of-date.
 * ✅. —MartinZ (talk) 16:25, 25 February 2017 (UTC)

(N/A) Fiction.  (N/A) List incorporation.  

Verifiability & Original Research
  There are minor issues with the presentation of some sources. Please add a link to source [39] (Scientists say they've found a planet orbiting Proxima Centauri, our closest neighbor), and there are double-double quotes in reference [16] (Found! Potentially Earth-Like Planet at Proxima Centauri Is Closest Ever). Additionally, the following references are duplicates of each other:
 * ✅. —MartinZ (talk) 16:17, 25 February 2017 (UTC)

<li> One of the sources may be unreliable. <li> The following sources do not seem to support the content. I'm willing to bet I've missed something with some of these, but with the others, we either need a new source or we need to remove the content. <li>✓ Likely-to-be-challenged information is cited. </li> <li>✓ Statistics cited. </li> <li>✓ No original research. </li> <li>✓ No copyright violations / plagiarism. </li> </ol>
 * [50] and [53] (Breakthrough Initiatives)
 * ❌—they weren't duplicates; I have fixed their titles to make that clear. —MartinZ (talk) 16:07, 25 February 2017 (UTC)
 * [48] and [49] (VLT to Search for Planets in Alpha Centauri System - ESO Signs Agreement with Breakthrough Initiatives)
 * ✅. —MartinZ (talk) 16:10, 25 February 2017 (UTC)
 * [44] and [47] (Breakthrough Starshot)
 * ❌—they weren't duplicates; I have fixed their titles to make that clear. —MartinZ (talk) 16:14, 25 February 2017 (UTC)
 * [52] and [28] (Earth-sized planet around nearby star is astronomy dream come true)</li>
 * ✅. —MartinZ (talk) 16:15, 25 February 2017 (UTC)
 * [47] (Breakthrough Starshot), is probably not reliable: it's the company itself. Luckily it seems like [43] (Breakthrough Starshot: Mission to Alpha Centauri) can be used instead.</li>
 * ❌—I think the source can be used per WP:SELFSOURCE. —MartinZ (talk) 17:05, 25 February 2017 (UTC)
 * [34]a (The habitability of Proxima Centauri b - II. Possible climates and observability)
 * ❌—the text is supported by the source:
 * Article text ("a"), "However, Proxima Centauri b's orbital eccentricity is not known with certainty, only that it is below 0.35—potentially high enough for it to have a significant chance of being captured into a 3:2 spin-orbit resonance similar to that of Mercury, where a Proxima b day would be roughly equivalent to that of 7.5 Earth days;"
 * source, "the maximum possible eccentricity of Proxima b is 0.35", "an eccentricity above ∼0.06 would be sufficient to capture the planet into a 3:2 spin-orbit resonance similar to Mercury."
 * Article text ("b"), "Resonances as high as 2:1 are also possible";
 * source, "At higher eccentricities, higher resonances such as the 2:1 become possible as well."
 * Article text ("c"), "The European Southern Observatory estimates that if water and an atmosphere are present, a far more hospitable environment would result. Assuming an atmospheric N2 pressure of 1 bar and ∼0.01 bar of CO2, in a world including oceans with average temperatures similar to those on Earth, a wide equatorial belt (non-synchronous rotation), or the majority of the sunlit side (synchronous rotation), would be permanently ice-free;"
 * Article text ("d"), "Liquid water may be present only in the sunniest regions of the planet's surface in pools either in an area in the hemisphere of the planet facing the star or—if the planet is in a 3:2 resonance rotation—diurnally in the equatorial belt."
 * source ("c" and "d"), "We find that a broad range of atmospheric compositions allow surface liquid water. On a tidally-locked planet with sufficient surface water inventory, liquid water is always present, at least in the substellar region. With a non-synchronous rotation, this requires a minimum greenhouse warming (∼10 mbar of CO2 and 1 bar of N2)."
 * [32]a (Numerical simulation of possible surface temperatures on Proxima b (synchronous rotation))
 * ✅. —MartinZ (talk) 19:20, 25 February 2017 (UTC)
 * [29] (Life on a tidally-locked planet)
 * —removed "a", but kept "b" and "c" because they support the text:
 * Article text, "'In this case, it is expected that any habitable areas would be confined to the border region between the two extreme sides, generally referred to as the terminator line, since it is only here that temperatures might be suitable for liquid water to exist';"
 * source, "More likely a circular belt between the two sides—a sort of 'twilight zone'—could be the place for life to evolve and flourish".
 * Article text, "A large portion of the planet may be habitable if it has an atmosphere thick enough to transfer heat to the side facing away from the star"; **source, "The constant air circulation would actually circulate the temperatures extensively and extremes in temperature would mitigate."
 * [25] (A Detailed Study of Opacity in the Upper Atmosphere of Proxima Centauri)
 * ✅. —MartinZ (talk) 10:20, 26 February 2017 (UTC)
 * [24] (The Solar Neighborhood. XXXI. Discovery of an Unusual Red+White Dwarf Binary at ~25 pc via Astrometry and UV Imaging)
 * ❌—text is supported by the source: Article text, "apparent magnitude of 11.13"; source, "Because Proxima is very bright at optical wavelengths (V [i.e., apparent magnitude] = 11.13)."
 * [20]b (Proxima b By the Numbers: Possibly Earth-Like World at the Next Star Over)
 * ❌—because it supports the text: Article text, "confirmed the existence of Proxima Centauri b"; source, "An Earth‐like alien planet orbiting a star known as Proxima Centauri—Earth's closest stellar neighbor—has been identified by astronomers from the European Southern Observatory (ESO)."
 * [14]b (The habitability of Proxima Centauri b: I. Irradiation, rotation and volatile inventory from formation to the present)
 * ❌—text is supported by source:
 * Article text, "'However, Proxima Centauri b's orbital is not known with certainty, only that it is below —potentially high enough for it to have a significant chance of being captured into a resonance similar to that of Mercury, where a Proxima b day would be roughly equivalent to that of 7.5 Earth days [emphasis added]';"
 * source, "'we can reproduce the observed upper limit (, given by Anglada‐Escudé et al. 2016) ... Finally, if the orbit is still eccentric as might be the case here, trapping into a resonance, such as the  resonance of Mercury, becomes possible (Goldreich & Peale 1966). [emphasis added]'."
 * [12]c and d (The exoplanet next door). Maybe these are supposed to cite the article itself, rather than the news story about it?</li>
 * —changed the text supported by "c", but kept "d" because it supports the text: Article text, "The planet may be within reach of telescopes and techniques that could reveal more about its composition and atmosphere, if it has any."; source, "But researchers are excited because, at just 4.25 light-years away, the planet may be within reach of telescopes and techniques that could reveal more about its composition and atmosphere than that of any other exoplanet discovered to date." —MartinZ (talk) 21:43, 25 February 2017 (UTC)

Topic Coverage
<ol> <li>✓ Addresses main aspects of topic. </li> <li>✓ Stays focused. </li> </ol>

Illustrations
<ol> <li>✓ Images present if possible. </li> <li>✓ Correct copyright tags. </li> <li>✓ Images relevant. </li> <li>✓ Captions appropriate. </li> </ol>

Other

 * ✓ Neutral point of view.
 * ✓ Stable.
 * Some previous review issues have not been addressed (restated elsewhere in this review).
 * ✓ No technical issues.