Talk:TRAPPIST-1/GA1

GA Review

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Reviewer: Robminchin (talk · contribs) 21:03, 3 March 2023 (UTC)

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

1. It is reasonably well written.

   a. (prose, spelling, and grammar):

   After a few iterations (see below) to clear up some individual points of confusion, this standard was reached.

   "The faint radiation at short wavelengths that TRAPPIST-1 emits has been measured with the XMM-Newton satellite" would be better referring to X-rays, which most people have heard of, rather than "short wavelengths".

   True, but here we also consider hard UV radiation not just X-rays. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   I still think it would be better to write out "X-ray and ultraviolet" in that case Robminchin (talk) 03:29, 5 March 2023 (UTC)

   Done, the source does not specify which one but from context it seems clear these are examples. Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   "Slightly larger than Jupiter, its radius is 11.9% that of the Sun." would be better reversed, i.e. "Its radius is 11.9% of that of the Sun, making it slightly larger than Jupiter".

   Done. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   Use lc=y with {{as of}} to get lower case

   Done. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   "The Sun will leave the main sequence", not "its main sequence"

   Done. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   "the existence of gas planets more than 4.6 times as massive as Jupiter at an orbital period of 1 year, and of a planet more massive than 1.6 Jupiter masses at 5 years can be ruled out" should be all singular or all plural. It should also be "with an orbital period" (or "with orbital periods")

   Done, I think. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   "The inclinations of the orbits ... They are highly circular" – "They" here refers to the inclinations, when the fact referenced refers to the orbits.

   Done. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   The text discusses orbits in terms of inclinations from the ecliptic, while the table presents what must be inclinations from the pole. It doesn't really matter which convention is used, but it should be the same one.

   Can't do that w/o having a way to convert from one to the other, and I don't have a source for the pole/ecliptic angle to convert. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   I've looked through the Agol et al. paper and worked out what is being said here. The reference to inclination relative to the ecliptic confused me, but the table is inclinations relative to the plane of the sky (i.e. the normal way of talking about inclinations in astronomy). It might be better to talk about dispersion in inclination (the phrase used by Agol et al.) than inclination relative to the ecliptic. I also notice that Agol et al ddau that their result "implies that the TRAPPIST-1 planetary orbits are extremely flat, even flatter than the Galilean moons that have a dispersion in inclination of 0.25°", which is a tighter constrain on the dispersion than the 1° from Satyal & Cuntz 2019 currently mentioned, so it works probably be worth using this instead.

   Changed this accordingly; perhaps we can say "less than one tenth of a degree"? Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   From the numbers given by Agol et al., That would seem accurate.

   Done. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   "The resonances make the planets go alternately ahead and behind in their orbits over the resonance periods, in greater amounts than simple estimates indicate, something which makes studies of the system easier" I doubt this is going to help anyone who doesn't already know what an orbital resonance (link to this article) is understand what is going on here. The resonances enhance the exchange of angular momentum between the planets, resulting in variations – earlier or later – in their transit times (in front of TRAPPIST-1) that can be measured. This makes possible the derivation of masses and densities for the planets that would otherwise be impossible. Note that it is the combination of resonances and transits, not just resonances, that enables this analysis.

   Do you think your formulation The resonances enhance the exchange of angular momentum between the planets, resulting in variations – earlier or later – in their transit times (in front of TRAPPIST-1) that can be measured. might work as a rewrite? Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   That might work, yes.

   Did a rewrite. Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   To say that tidal locking "can imply that the rotation of a planet and its revolution around its star are synchronised" is wrong – this is what tidal locking means, not something it implies.

   According to tidal locking it means that the planet's rotation is stable, which is not the same thing as synchronization - 3:2 resonances are stable but not synchronized. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   I see what you're saying. I think 'implies' is the wrong word here though.

   Rewrote this a bit. Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   "Other processes that can act to prevent synchronous rotation are triaxial torques of the planets, which would allow them to enter 3:2 resonances." From the paper cited, this is about the intrinsic triaxial deformation of the planet – not triaxial torques, and not a process.

   Rewritten. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   "higher wavelength" -> "longer wavelength"

   Done. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   "but at least" has the idiomatic meaning of "but there is some good in this bad situation", which I don't think is intended here

   Rewritten. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   "radiation" in non-technical English normally refers to radioactive decay products, rather than electromagnetic radiation. While the usage here is not wrong, you might want to use, e.g., "infrared light" for better comprehension.

   I see, but the problem is that light specifically refers to human-visible radiation. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   Infrared light (and ultraviolet light) are both commonly used, e.g [in NASA's "Tour of the Electromagnetic Spectrum]. The light article on Wikipedia says that 'visible light' or 'light' used without a qualifier that refers to human-visible light, but infrared light – with the qualifier – is perfectly acceptable, as its use by NASA shows.

   Done. Jo-Jo Eumerus (talk) 15:30, 8 March 2023 (UTC)

   "three or four planets ... are located inside the habitable zone" is accompanied by two lists of three planets (containing four planets in total). If the lists are correct, there are three planets in the habitable zone: e, f and one of d or g, depending (presumably) on the definition of the habitable zone used. It might be worth including a reference to the Habitable Exoplanets Catalog (https://phl.upr.edu/projects/habitable-exoplanets-catalog), which uses definitions of habitability beyond just whether a planet is in the habitable zone (nb, this isn't required for the 'broad coverage' in the GAN criteria, it's just a suggestion)

   I prefer to leave detailed discussion on which planet is habitable to the individual planet articles. Yes, which one(s) are habitable is an unsettled question. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   Fair enough, but that the text says "three or four" planets are in the habitable zone but then contradicts itself by giving two options of three planets each still needs to be addressed.

   Did a rewrite, but I really don't know how to formulate this one. Jo-Jo Eumerus (talk) 15:30, 8 March 2023 (UTC)

   "Additionally, given that the planets are most likely tidally locked, water could become trapped on their night side and unavailable to support life" appears to be using "tidally locked" to mean synchronised, in contrast to earlier.

   Rewritten. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   It's probably worth mentioning at the start of the habitable zone section that the habitable zone for the TRAPPIST-1 system is much closer in to the star than the habitable zone of the Solar System is to the Sun because the star is much smaller and cooler (any decent astronomy text book that discusses habitable zones should be usable as a reference for this).

   Done but with a different reference. I think the wording can be improved, however. Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   The sentences "Its planetary system was discovered by a team led by Michaël Gillon, a Belgian astronomer[290] of the University of Liege,[13] in 2016,[80] during observations made from the La Silla Observatory, Chile,[229][291] using the TRAPPIST telescope. Anomalies in the light curves[aj] measured by the telescope in 2015 led to the discovery of TRAPPIST-1b and TRAPPIST-1c and a third planet." are taking about the same event twice, using different dates. Ref 80 gives a date of 2015, not 2016 for the discover – 2016 is the when the discovery was announced. This needs to be re-worked into a single narrative.

   Rewrote this a bit. Jo-Jo Eumerus (talk) 15:30, 8 March 2023 (UTC)R

   In the Formation history section, it should probably be included in the footnote that 'clearing the neighbourhood' is part of the IAU criteria in the definition of a planet in the Solar System (see the IAU resolution linked by the source cited)

   Expanded a bit, do you think that it works now? Jo-Jo Eumerus (talk) 10:05, 11 March 2023 (UTC)

   For Trappist-1d, "it may be at the inner edge, or beyond, the habitable zone" is confusingly worded, as "beyond the habitable zone" would imply past its outer edge. Looking at the source cited, they think planet d has a semi-major axis between 0.033 and 0.093 AU, while they define the HZ as 0.024 to 0.049 AU, so they are actually saying that it is either within or beyond the outer edge. This is because what they thought was planet d in the 2016 paper cited here turned out to be multiple planets. This source shouldn't be cited here, as its conception of planet d has been superseded by later work.

   Changed, but I kind of wonder if there is a synonym for "beyond" that doesn't mean "inside". Jo-Jo Eumerus (talk) 10:05, 11 March 2023 (UTC)

   It still seems confusing to me. Possibly re-writing to something like "it is close to the inner edge of the habitable zone, but whether it has liquid water or has suffered from a runaway greenhouse effect that would render it non-habitable is dependent on detailed atmospheric conditions" would reflect what Turbet et al. 2020 say.

   That seems to be a better formulation; I've put it in. Jo-Jo Eumerus (talk) 12:07, 15 March 2023 (UTC)

   It looks like the references for the mass and the bolometric luminosity in the infobox have become confused. These are given as being from reference [5], Lienhard et al. 2020, but are actually from the same table in reference [6], Agol et al. 2021, as the radius. As this is a simple labelling error, I've just gone in and fixed it.

   Thanks, these data tables are a nuisance to maintain. Jo-Jo Eumerus (talk) 12:07, 15 March 2023 (UTC)

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

   This was fine.

2. It is factually accurate and verifiable.

   a. (reference section):

   References were fine

   b. (citations to reliable sources):

   All verified.

   c. (OR):

   A few issues were identified and successfully addressed (see below)

   Brown et al. 2021 (reference 1) is a citation of the paper describing the catalogue, which does not actually contain the information (RA, Dec, proper motions, etc.) that it is being cited as verifying. This is to be found in the GAIA catalogue, which is linked from Brown et al. The actual catalogue should be cited.

   I see. Is this or this the page to cite? Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   The link should be to the actual archive where the data can be accessed, i.e. [1]. It would be good to put in something like |at=Search using name "2MASS J23062928–0502285"| in the cite template to tell people what they have to do to access the entry for TRAPPIST-1 in the catalogue.

   See, that's the thing - I don't see a search function anywhere. Does the parameter on Template:Cite Gaia EDR3 do the job? Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   Odd, I see a Search tab at the top of the page. I didn't know about that template, but it sounds ideal. This is what it returns for TRAPPIST-1: Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

   I've put it in, but apparently it says nothing about the absolute magnitude and distance? Jo-Jo Eumerus (talk) 15:44, 6 March 2023 (UTC)

   The parallax gives the distance (this might be worth a footnote): distance in parsecs = 1/parallax in arcsecs (this is the definition of a parsec). With the apparent magnitude (from Costa et al. 2006) and the distance, the absolute magnitude can be calculated as noted a couple of comments down. These are simple calculations using well-known formulae (should probably be referenced to a basic astronomy text-book).

   I have to confess that I am not familiar with these formulas. Do you know them? Jo-Jo Eumerus (talk) 10:05, 11 March 2023 (UTC)

   Actually, it appears the calculation is being done by {{Starbox astrometry}} from the parallax, giving the distance of 12.47 pc in the infobox at the top of the article.

   I see, although that doesn't resolve the magnitude thing. Jo-Jo Eumerus (talk) 12:07, 15 March 2023 (UTC)

   Costa et al. 2006 does not verify the radial velocity. Some other items for which this reference is cited (the apparent magnitudes) are in the table on page 1240, which should be listed alongside page 1234 in the citation.

   I think I got this? Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   I think you missed the first one (V band). Looking at how the citations are done, you could actually use just p=1240 for all of the magnitudes and keep p=1234 for the spectral type.

   Resolved. Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   The footnote explaining the calculation of the visible luminosity starts with the absolute magnitude, but only the apparent magnitude had been given previously. It should include the calculation of the absolute magnitude. Also, I get 18.32 rather than 18.4 for the absolute magnitude, based on the distance from GAIA, and thus a higher value for the visible luminosity; it looks like this calculation used the older distance from Costa et al. 2006 and needs updating.

   I did try to see if Gaia DR3 has the absolute magnitude, but it doesn't seem like it; do you know of a source I could use? Commented this part out in the meantime. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   You've got the distance from GAIA DR3, which gives you the distance modulus, μ = –5 log₁₀(d_pc) – 5. This is the difference between the absolute and apparent magnitudes, so you can get the absolute magnitude using M_V = m_V – μ. (Not to be confused with μ for proper motion, astronomy ran out of Greek letters apparently) As long as this calculation is footnoted it should be fine as a basic calculation. Robminchin (talk) 03:29, 5 March 2023 (UTC)

   See above re Gaia citation. Jo-Jo Eumerus (talk) 16:38, 5 March 2023 (UTC)

   "TRAPPIST-1's seven planets ... are named in alphabetic order according to their discovery and distance from TRAPPIST-1" doesn't quite make sense and isn't fully verified. They are either named in alphabetical order according to their discovery, with this happening to fall out as also being in order of distance from TRAPPIST-1, or vice-versa. The source cited says "Conveniently, all planets in all systems are lettered in alphabetical order according to their distance from the parent star(s)", which implies – but doesn't verify – that they are named by discovery and that this has conveniently aligned with the distances from the start of the systems they are studying. A better source is wanted here

   Rewrote this one. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   "Observations with the Atacama Large Millimeter Array telescope have found no evidence of a circumstellar dust disk, implying that if it does exist it is of low mass. It is thought that most of the solid material around TRAPPIST-1 was converted into planets." The use of "low mass" here, while it is used in the source doesn't really convey anything out of its context. The source does not verify the second sentence – it only raises this as a possibility, not what the authors (or anyone else) thinks had happened.

   Rewrote this. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   d. (copyvio and plagiarism):

3. It is broad in its coverage.

   a. (major aspects):

   This was fine.

   b. (focused):

   This was fine.

4. It follows the neutral point of view policy.

   Fair representation without bias:

   A small number of points needed clarification; these were successfully addressed.

   The statement that "systems with multiple planets like TRAPPIST-1 might not be widespread", while referenced, seems to be at odds with the statement in Delrez et al. 2022 that: "With an effective temperature of 2850 ± 75 K (Sect. 3), LP 890-9 is the second-coolest star found to host planets after TRAPPIST-1. Interestingly, all these systems – including LP 890-9 – are multi-planet systems, in line with the observation that compact multi-planetary systems should be a relatively common outcome of planet formation around low-mass stars (e.g., Coleman et al. 2019; Miguel et al. 2020; Mulders et al. 2021)." It seems there is either a need for clarification or that there may be a dispute here that should be described.

   Expanded on this a bit. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

   The statement "The resonances continually excite the eccentricities of the TRAPPIST-1 planets, preventing their orbits from becoming fully circular" is at odds with the earlier statement that "The inner two planets' orbits may be circular".

   Not sure how to formulate this one ... it's a "how circular" kind of deal. Jo-Jo Eumerus (talk) 12:24, 4 March 2023 (UTC)

5. It is stable.

   No edit wars, etc.:

   No edit wars.

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):

   No issues with this.

   Doesn't affect pass/fail for GA, but I noted that both of the ESO image of light curves (Curvas de luz de los siete planetas de TRAPPIST-1 durante su tránsito.jpg and Curva de luz de TRAPPIST-1 que muestra los eventos de disminución de la luz causados por el tránsito de los planetas.jpg) are tagged as 'superseded' on Wikimedia Commons as png versions are now available.

   Done. Jo-Jo Eumerus (talk) 10:05, 11 March 2023 (UTC)

   b. (appropriate use with suitable captions):

   Media were informative and relevant.

7. Overall:

   Pass/fail:

   Congratulations, this is a good article.

(Criteria marked are unassessed)