Talk:TRAPPIST-1

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natural satellites of the exoplanets

Would these even be possible or offer more or potentially equal chances of habitability or possibilities of liquid water or ocean worlds

Any satellites of any of these 7 planets would necessarily be much smaller than the planets, and therefore would not likely have liquid water. A body needs enough mass and gravity to hold an atmosphere. No atmosphere, any liquid water evaporates and is lost. One of the reasons these planets are exciting is that they are the right size and temperature to have liquid water.4.31.13.17 (talk) 19:08, 24 February 2017 (UTC)

merge all planet pages onto star page

Should be moved because b, c and d articles all are the same, with little variations and little detail. --MarioProtIV (talk) 21:17, 13 May 2016 (UTC)

Wait. There will be more data coming up regarding the planets with follow up studies.Quantanew (talk) 04:20, 15 May 2016 (UTC)

These articles have barely been touched since these comments. Some numbers have been updated (and are now seriously out of date) but they are still pretty little stubs repeating information already in this article. Lithopsian (talk) 22:19, 22 February 2017 (UTC)

Closest transiting planets?

Is this the closest star with transiting exoplanets known?--Roentgenium111 (talk) 17:03, 28 June 2016 (UTC) One of the closest at least. Quantanew (talk) 13:50, 30 June 2016 (UTC)

Nope... Proxima Centaury b is the closest known exoplanet, 4.2 light years from earth. See List of nearest exoplanets (there are at least 11 "potentially habitable" exoplanets, on 38 confirmed and 78 total, closer than those in Trappist-1 system)— Preceding unsigned comment added by 62.18.143.111 (talk)

I was talking about transiting exoplanets.--Roentgenium111 (talk) 19:59, 23 February 2017 (UTC)

Alpha Centauri Bc "On 25 March 2015, a scientific paper by Demory and colleagues published transit results for Alpha Centauri B using the Hubble Space Telescope for a total of 40 hours.[99] They evidenced a transit event possibly corresponding to a planetary body with a radius around 0.92 R⊕." HTH Kiore (talk) 06:40, 24 February 2017 (UTC)

Okay, but this is hardly a known planet. The paper does not even dare to give it a label like "Bc", which seems to have been a WP invention... --Roentgenium111 (talk) 16:29, 24 February 2017 (UTC)

add specific gravity to planets list

When somebody gets this data, would be nice to see the specific gravity of each of the planets where available. (And the relation to Earth's since that's really our only frame of reference...) --Enorl76 (talk) 19:13, 22 February 2017 (UTC)

That will probably need to wait for radial velocity observations to be complete. Kortoso (talk) 23:22, 23 February 2017 (UTC)

Make this page about the system rather than the star

Given that the NASA announcement is about the system as a whole rather than the star, and planets being of high importance, I suggest that we make this page about the system rather than the star. The title would then be something like "The TRAPPIST system" . -- Sharanbngr (talk) 19:24, 22 February 2017 (UTC)

It's normal to name articles after stars, including where the system is the main focus. Rothorpe (talk) 19:34, 22 February 2017 (UTC)

(edit conflict) That is highly atypical for Wikipedia articles on exoplanetary systems. It's fine as it currently is, being about the star with details about the associated system. Separate articles for the planets may follow once they become notable enough. — Huntster (t @ c) 19:36, 22 February 2017 (UTC)

I wasn't aware about the existing protocol. Thanks for the clarification Sharanbngr (talk) 19:40, 22 February 2017 (UTC)

It's good to have consistency among the exoplanetary systems, but note that this "protocol" is inconsistent with how we treat our own system: The article Sun doesn't even mention all of its planets, which are detailed only in Solar System. --Roentgenium111 (talk) 16:17, 24 February 2017 (UTC)

Order of planets wrong

Artist's concept of what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star.

Some of these planets were discovered a year ago so the "artist's concept" image you're using is wrong. Compare it with the table of data, planet d is the farthest one out. Enough people are spreading this confusion, I hope you get it corrected here. 207.161.172.171 (talk) 19:45, 22 February 2017 (UTC)

It's shameful that even the NASA artist got it wrong. Planet d is the farthest one out, the order is b, c, e, f, g, h, d. 207.161.172.171 (talk) 19:51, 22 February 2017 (UTC)

Or is it the chart data and article on planet d that are wrong?

TRAPPIST-1, stellar object
TRAPPIST-1 b, planet, semi-major axis: 0.0111±0.0003 AU
TRAPPIST-1 c, planet, semi-major axis: 0.0152±0.0005 AU
TRAPPIST-1 d, planet, semi-major axis: 0.0214+0.0007−0.0006 AU
TRAPPIST-1 e, planet, semi-major axis: 0.0282+0.0008−0.0009 AU
TRAPPIST-1 f, planet, semi-major axis: 0.0371±0.0011 AU
TRAPPIST-1 g, planet, semi-major axis: 0.0451±0.0014 AU
TRAPPIST-1 h, planet, semi-major axis: 0.063+0.027−0.013 AU

207.161.172.171 (talk) 20:06, 22 February 2017 (UTC)

Today's Nature paper named them in order of increasing orbital period, with b the 1.5 days planet, and h the ~20 day planet. So either the authors have it wrong, or The planets are designated in the order of their discovery here is wrong. Currently TRAPPIST-1d seems to be about the planet that is designated g in the paper. Gap9551 (talk) 22:02, 22 February 2017 (UTC)

Exoplanets are named in order of their discovery. However, in this case it is the same as the order of distance from the star, partly because the planets were not all discovered at different times. Somewhat (but not entirely) coincidentally, the first three planets discovered were the inner three, then the outer four were discovered (or at least announced) together, so the orders all match up. Describe away ...Lithopsian (talk) 22:16, 22 February 2017 (UTC)

That's not correct in the original nature paper planet d was the current planet g. They changed the name and the order. Quantanew (talk) 01:22, 23 February 2017 (UTC)

The new Nature paper says These signals correspond to four new transiting planets, named, respectively, TRAPPIST-1d, TRAPPIST-1e, TRAPPIST-1f and TRAPPIST-1g, suggesting that it is h, not g, that corresponds to the old d. But the orbital period was quite uncertain in the 2016 Nature paper so maybe it wasn't entirely clear which planet they saw then (apart from b and c). Gap9551 (talk) 15:17, 23 February 2017 (UTC)

No substitute for reading the paper I suppose :) It describes that the two transits originally used to identify "TRAPPIST-1d" were from different objects. Further observations showed that the "different objects" were four planets now named d to g. TRAPPIST-1h is described later, somewhat tentatively, on the basis of a single transit seen from Spitzer. I suppose it is somewhat a matter of semantics whether you describe d to g as four new planets (and minus one planet previously named d), or three new planets (going from 3 to 6 planets). Overall, the paper describes 7 planets where previously there were 3, but it isn't quite true to say that the four extra ones are d to g or that "old d" is now called h. Lithopsian (talk) 15:37, 23 February 2017 (UTC)

Metallicity

The metallicity of "0.04 ± 0.08" makes no sense (makes it sound likely to have an impossible negative metallicity), and calling it "109% the solar amount" when the Sun is listed at 0.0122 sounds wrong both mathematically and in terms of significant digits. Capybara (talk) 20:09, 22 February 2017 (UTC)

Negative metallicity is not impossible at all, it just indicates having less heavy elements than our Sun.Mihaiam (talk) 20:35, 22 February 2017 (UTC)

See the entry on metallicity. Stellar metallicities are typically cited as [Fe/H] or [M/H]. This is logarithmic and relative to the sun, so a star with 1/10th the metal content (relative to hydrogen) of the sun would have [Fe/H] = -1.Dab8fz (talk) 00:12, 23 February 2017 (UTC)

Aha, that makes sense, sorry for misunderstanding. But it's still misleading to quote it at "109% of the solar amount" when the error indicates between 96% and 113%. How about changing that to just "with a metallicity similar to the sun's."? Capybara (talk) 18:51, 24 February 2017 (UTC)

4–5 trillion years

When the article says 4–5 trillion years it means 4-5.000.000.000.000? -Theklan (talk) 20:18, 22 February 2017 (UTC)

Theklan, yes, trillion (short scale). Dwarf stars have extremely long and stable lives. — Huntster (t @ c) 20:30, 22 February 2017 (UTC)

Thanks Huntster! Just making the translation for Basque Wikipedian and wondering if I had to write down billion instead of trillion. -Theklan (talk) 20:38, 22 February 2017 (UTC)

Sorry but, hasn't the universe only existed for like 8 billion years or something? Socialistboyy (talk) 21:38, 23 February 2017 (UTC)socialistboyy

Socialistboyy, see age of the universe. It is about 13.8 billion years. — Huntster (t @ c) 01:49, 24 February 2017 (UTC)

Is it a red dwarf?

The first occurrence of "red dwarf" is here more than halfway through the article: "red dwarf stars are subject to frequent, intense flares". It's not clear whether this statement even pertains to TRAPPIST-1. - Brianhe (talk) 23:58, 22 February 2017 (UTC)

The star is indeed a red dwarf, or at least a very massive brown dwarf. The spectral type is M8.2 +/- 0.1, so it's right in the expected range for flare stars.

• The star is red (no blue light, little green light). The star is young and very unstable. The planets are all closer to the star than Mercury. Thus one side is lock to the star. How is this earth like? I know politics has spin, but science is not where spin should be. "Habitable zone." label is joke.Telecine Guy (talk) 05:08, 23 February 2017 (UTC)

@Telecineguy: "Habitable zone" is indeed a potentially misleading term, but it has some sense to it. It excludes large regions of every system where people think planets are uninhabitable simply based on where they are. Within the zone, a lot of things have to go right besides just location -- remember, Venus and Mars are Earthlike planets near the border of the habitable zone. But the point is that based on what little is currently known you actually have to go there, measure temperatures, even dig through the soil and look for life before you can say they are definitely uninhabitable.

I would like to see more about whether large moons are possible for planets in these orbits around red dwarfs, since I would think that a large moon could tidally lock the planet onto itself and leave it with normal day and night. Certainly NASA thinks moons are possible - see File:NASA-RedDwarfPlanet-ArtistConception-20130728.jpg (if we find a bit more suggestion we might even use it as an image here). The moons themselves, if large enough, might even be habitable; or one of the transiting planets might actually turn out to be a double planet. Providence has granted us this fascinating system, but it's up to us to see what we can make out of it. Wnt (talk) 13:30, 23 February 2017 (UTC)

• Red dwarfs are far more variable and violent than the Sun. Red dwarfs are often covered in starspots that can dim their emitted light by up to 40% for months at a time, a stable ones variable is only, what 10% or 5 %. Our sun variable output is about 0.1 %. The planets here are not "Earth like" other than maybe is size, but that is where it ends. Mars is not Earth like, its gravity is too weak, Mars did not have enough gravity to hold on to its water or atmosphere. Gravity on Mars is so low a person could not "walk" on Mars, they would need to hop like men on the moon did. Words have meaning and "Habitable zone" has lost its meaning, just has honesty has been lost on this topic. What is the definition of "Habitable zone"? What does the average person think it means? Telecine Guy (talk) 06:01, 24 February 2017 (UTC)

Inclinations

As far as I know, the inclinations of these planets are all close to 90 degrees because they were all found by transiting the star. They are in other words inclinations relative to a plane perpendicular to the Earth-TRAPPIST1 axis. If you have a handy source for this you should explain it.

Also, it makes me wonder... is the TRAPPIST-1 star's rotation axis exactly 90 degrees (give or take at most a few tenths) perpendicular to the Earth-TRAPPIST1 axis? Or is it further off? (If it's further off does that mean there are probably dozens of other planets around the dwarf that don't transit?) Wnt (talk) 00:00, 23 February 2017 (UTC)

I wonder if the rotation axis of the star can be measured. You'd probably need to measure Doppler shifts on different sides of the star disk, which the star may be too small for. But likely the axis will be perpendicular to the plane in which the planets orbit. If anything is known about the axis orientation it would be interesting to add it to the article. I doubt there are many more planets at larger inclinations, at least nearby the star. The whole system is very "flat", all planets transit within 0.42 stellar radii from the middle, based on semi-major axes and inclinations. (The orbital period gives the orbital velocity, which, combined with the transit duration, tells us if a planet is transiting the star near the middle or closer to the edge on either side.) Non-transiting planets near the star would also have had a noticeable gravitational effect on the transit timing variations (that were used to estimate the planet masses). Gap9551 (talk) 15:38, 23 February 2017 (UTC)

The rotational axes of stars does not always correlate with the orbital planes of their planets. Kortoso (talk) 23:26, 23 February 2017 (UTC)

Alternative version

TRAPPIST-1
The Ultra-Cool Dwarf Star

Today's top story on ITN and Google revolves (literary) around an Ultra-Cool Dwarf Star. I was immediately struck by the term "ultra-cool" dwarf star and got a quite different picture in my mind of what ultra-cool was. A quick Google picture search confirmed this view. So here is the alternate version of this new celeb. :) cart-Talk 13:37, 23 February 2017 (UTC)

Earth-Like?

I think the term "earth like" may be better re-stated as 'earth-sized'. The term 'earth-like' would seem to mean a plant that is, well, like the earth. That is: it rotates (e.g. isn't tidally locked to the primary), has an atmosphere (that wasn't stripped away by the primary), and would likely support earth-type life (which the article states (in two places) as being un-likely.

We have a long way to go before we can say any more about any exoplanet than its size and mass. Kortoso (talk) 23:28, 23 February 2017 (UTC)

We do know that the TRAPPIST-1 planets are likely tidally locked. Also, the atmospheres of b and c have already been studied (though not conclusively) in the current paper. --Roentgenium111 (talk) 16:06, 24 February 2017 (UTC)

They haven't discovered it fully yet I think.....!!!

Dlritesh (talk) 11:50, 7 March 2017 (UTC)

Is there water on the surface?? Dlritesh (talk) 11:51, 7 March 2017 (UTC)

Discovery date of TRAPPIST-1

When was the star itself first observed? Was it known of before the first three planets were discovered in 2015? If not, how did the astronomers know to focus their gaze on that patch of sky? 2A02:C7F:DA15:9100:7C32:8C43:7135:BE4A (talk) 17:18, 23 February 2017 (UTC)

The star was "known" in the sense that it existed in the catalogues of previous sky surveys. I believe it was first observed by the 2MASS survey (along with many, many other stars). It did not get any attention until the first planets were observed.Dab8fz (talk) 17:48, 23 February 2017 (UTC)

Trappist-type planets and history of astronomy

Speculation I know - but 'entities on such planets' who are in a position to develop the science of astronomy will have a (local)heliocentric concept of their solar system from the start, rather than 'the pre=Copernican-Earth-centric system' that once prevailed (a simplification for convenience). Jackiespeel (talk) 19:15, 23 February 2017 (UTC)

Very confusing planetary data statistics on this page vs the planet-specific one

Title says it all. For example TRAPPIST-1d is stated in the table to have a mass of 0.41±0.27 M⊕ (giving a maximum of ~0.68 M⊕), while on the article for TRAPPIST-1d it is stated to be in the ballpark of 1.7 M⊕, much higher than what this article claims. The radius is another point of dispute, with the table stating it as 0.772 ± 0.030 R⊕ (upper bound of ~0.80R⊕) yet the article states the radius as around 1.16 R⊕. Admittedly these numbers are still very ambiguous, but it would be nice to be consistent between the two groups of data. TRAPPIST-1d is the only case where this issue is pretty prevalent, all the other planets have stats common to each other as far as I can tell. I would edit one to state data that matches the other but at this point I am unable to tell from the sources which of the two is the more accurate, regarding the large error bars inherit in this discovery.

EDIT: the way these articles are usually structured this article shouldn't even be delving into too much detail as to the planets, and instead should just have names and perhaps a sentence or two with the bulk data in the planet specific article. Caelus5 (talk) 00:04, 24 February 2017 (UTC)

The data in the new Nature paper are the most accurate available. Gap9551 (talk) 02:49, 24 February 2017 (UTC)

The article on TRAPPIST-1d was probably originally created based on the information in the first Nature paper by Gillon et al., published in May 2016. The two transits on which the original '1d' candidate was based turned out to be due to two different objects, so that candidate has been dropped altogether in the 2017 Nature paper. I suspect the article TRAPPIST-1d may need to be updated using data from the more recent paper. --Robert.Allen (talk) 03:00, 24 February 2017 (UTC)

Regarding coverage of the planets in the system, it is a highly unusual and surprising planetary system because of the large number of earth-like planets (rocky and many in the habitable zone), so I don't think providing more detailed information on each of these in the main article is out of place. It is helpful to include a detailed summary all the planets for purposes of comparison. --Robert.Allen (talk) 03:00, 24 February 2017 (UTC)

Okay, thanks for the swift reply. Judging by this I take it the TRAPPIST-1d article is the one in need of updating, is it not? Caelus5 (talk) 04:24, 24 February 2017 (UTC)

Yes. --Robert.Allen (talk) 05:02, 24 February 2017 (UTC)

Doesnt matter much if we might be wrong with some of the Math,

After we explore our Solar System.. The first Star we going too after that.. is that one.. We'll learn more then.. — Preceding unsigned comment added by 81.155.215.141 (talk) 06:54, 25 February 2017 (UTC)

TRAPPIST-1 System

I created an article on TRAPPIST-1 System article, but it needs major expansion. Star system section in this article needs to be moved. I ask for assistance. FriyMan ^talk 13:10, 27 February 2017 (UTC)

FWIW - the newly suggested TRAPPIST-1 System article created by User:FriyMan seems unnecessary at this time - the present articles (ie, TRAPPIST-1; TRAPPIST-1b; TRAPPIST-1c; etc) seem sufficient to describe the TRAPPIST-1 star and exoplanetary system imo - however - Comments Welcome from other editors of course - in any case - Enjoy! :) Drbogdan (talk) 15:01, 27 February 2017 (UTC)

I agree, we probably really only need one article. The star itself is mainly notable because of its planets. Probably better to keep the information in one place for now. --Robert.Allen (talk) 16:10, 27 February 2017 (UTC)

Yes. See section #Make this page about the system rather than the star above. I'm going to be bold and redirect that article back to this one as being highly premature in its creation. — Huntster (t @ c) 16:15, 27 February 2017 (UTC)

Red versus brown dwarf: does anyone have a figure for the lithium, etc.?

In a tribute to the universal moronicy of Man, I haven't yet laid hands on that locked-up Nature article. We ought to have a red vs. brown discussion - in the article, but here might be a place to start. Some of the conversations above suggest the star could be a brown dwarf. But my impression is a brown dwarf is distinguished by a lack of lithium burning, so that a star older than 100 million years with lithium is a brown dwarf. True, our articles go on to suggest that some stars may be defined as brown dwarf because they do lithium burning but nothing else - they therefore lose their lithium despite being brown dwarf - but only given a mass of > 65 Jupiter masses. TRAPPIST, as it happens, is "0.08 solar masses +- 0.009" = 0.071 to 0.089 solar masses = 74 to 93 Jupiter masses. So it is close enough to this boundary that an independent measurement of lithium seems informative. Brown dwarfs can be "up to 80 Jupiter masses" according to our article, and can be spectral class M, so this isn't that easy to figure out, mind. M8V is a class typical of the smallest and dimmest red dwarfs. Anyway, I'd like to see some description of what about the star suggests it's >= 500 million years old, whether its long predicted life is based on a solid knowledge of which type it is and so on. Wnt (talk) 01:13, 28 February 2017 (UTC)

Gillon et al 2016 : High resolution optical spectroscopy failed to detect significant absorption at the 6,708 A line of lithium (ref 36), suggesting the star is not a very young brown dwarf, rather it is a very low-mass main-sequence star [which is fusing H and has already burned all of its lithium]. "This is in agreement with its thick disk kinematics, its slow rotation (projected rotational velocity vsini = 6±2 km s^-1), its moderate activity, and its reported photometric stability, all of which point to an age of at least 500 Myr (ref 13)." [I've omitted some of the other refs they cite. I have not yet come across a figure for the spectrum.] --Robert.Allen (talk) 02:55, 28 February 2017 (UTC)

If you look at [1] Fig.2, you will see that the lack of lithium together with the known temperature puts a lower limit on the age. Ruslik_Zero 19:38, 4 March 2017 (UTC)

I know this section is intended to suss out the purely scientific definition of whether this is a red dwarf system, but I should point out that many reliable sources state it as such, which is the measure by which our article should follow. As a sampling: NASA, NASA, Time, Popular Mechanics, Centauri Dreams, Business Insider, European Southern Observatory, The Daily Telegraph, Universe Today, Financial Times, and I could keep going with prominent reliable sources. Surely this warrants labelling it as such in the article? — Huntster (t @ c) 04:34, 28 February 2017 (UTC)

I don't really disagree with you, but it is interesting that neither of the two Nature papers from the Gillon group refer to TRAPPIST-1 as a "red dwarf", rather they call it an "ultracool dwarf". Either the authors themselves chose to call it that, or the Nature reviewers required them to. Presumably all of these web pages you have linked are ultimately based on the Gillon papers, so maybe somewhere along the line one or more of these subsequent authors decided to discard scientific caution and call it a red dwarf and others followed suit. --Robert.Allen (talk) 07:15, 28 February 2017 (UTC)

I can't deny there is a consensus for a red dwarf, but this article should go into scientific detail. If in business "it's not what you know but who you know," then in science "it's not what you know but how you know." The more we can figure out about the history of this journey the better the story we can write about it. Wnt (talk) 02:06, 1 March 2017 (UTC)

Artist's impression/Artist concept

Inasmuch as there don't seem to be any 2MASS photographs of TRAPPIST-1, I'm fine with artist's impressions and artist concepts, but we might need to fine tune the nomenclature. The lead illustration is based quite closely on transit data; the others feature suitable embellishments (which lies quite firmly in the venerable Chesley Bonestell tradition of Space art). For that matter during the Space Race itself "Artist's impression" was standard NASA lexicon. NASA employed artists four years after its founding, and for good reason!

http://newatlas.com/how-are-planets-painted/42763/

kencf0618 (talk) 22:45, 1 March 2017 (UTC)

Water loss

It's too bad, although not that surprising, that the fact that these planets may not have water was pulled from the lead [2]. This source [3] concludes that one or two of the planets *may* have water, depending on what models you prefer to use, and what starting composition you feel like using. Given that those researchers felt it necessary to write a paper arguing that water is not completely out of the question, that's anything but a compelling reason to remove any mention of doubt of it from the lead. And, a pet peeve of mine: many readers won't understand that "habitable zone" =/= "habitable". Maybe some alternative wording would be more palatable? Geogene (talk) 00:49, 2 March 2017 (UTC)

@Robert.Allen: Geogene (talk) 00:50, 2 March 2017 (UTC)

You failed to provide a reference for your statement, so I removed it. If we can find a reference that supports it (other than a random blog post), we should include it. Such a critique might be published in the near future. In any case, we should not formulate our own critique based on sources that don't mention TRAPPIST-1. That would constitute original research. The reference we have, Gillon et al 2017, states on p. 458 that the authors ran a three-dimensional climate model (ref 26, developed for another red dwarf, Proxima Centauri b). Gillon et al assumed the TRAPPIST-1 planets are tidally synchronous (and also apparently that they have earth-like atmospheres) and deduced that planets e, f, and g could harbor water oceans on their surface. The same model results in a runaway greenhouse scenario for planets b, c, and d. They also cite Bolmont et al 2016, implying they have taken UV irradiation from the star into account, but few details are provided. --Robert.Allen (talk) 06:32, 2 March 2017 (UTC)

There are two estimates, one fifty times higher than the other. Certainly we should mention both, though not necessarily treating them as definitive. Wnt (talk) 17:49, 2 March 2017 (UTC)

I read Snellen's 'News & Views' item in the same issue of Nature. It may be be what we need for the lead. I've tried adding something general to the end of the second paragraph based on it. We can always add more specific arguments to the body of the article. --Robert.Allen (talk) 19:43, 2 March 2017 (UTC)

I see it's been removed as "redundant padding", which I suppose is probably true. --Robert.Allen (talk) 03:46, 3 March 2017 (UTC)

I don't think so, but if @Kencf0618: is going to hype the hell out of this article, there's probably enough of them to do it. Geogene (talk) 00:18, 4 March 2017 (UTC)

Wait, what? Please clarify. kencf0618 (talk) 00:38, 4 March 2017 (UTC)

Sorry, my meaning there should be clarified. In my experience, there are some types of articles that will be hyped and that can't be helped. Articles involving the possibility of alien life is one of those types. In this case, there appears to be controversy over whether any of these planets should be expected to have water on them, given hydrodynamic(?) escape and the radiation environment they're apparently being bathed in. It's not clear what the majority viewpoint is from the limited sources available, but as I expected one is being downplayed in the article in favor of the other. Geogene (talk) 00:48, 4 March 2017 (UTC)

I thank you for your explanation. Media reports aside, the standard nomenclature from the scientists involved use "Earth-sized" rather than "Earth-like," AFAIK. We await more data from the astronomers, and more Wikipedia nuance regarding this habitability zone and that. kencf0618 (talk) 01:26, 4 March 2017 (UTC)

We still have a lot to look for where the water estimates are concerned. When two vary by a factor of 50, I gotta wonder. When the difference between Earth and Mars is supposedly the magnetic field and the potential values of magnetic fields on the TRAPPIST planets aren't discussed in either of those two papers, I gotta wonder. I think it is a fair expectation that the planets will turn out to be unsatisfactory in some clear way, but not to know is a very exciting thing. We live on the one planet in the Cosmos that was sculpted by the loving hand of the Creator, and/or the anthropic principle, to be a homeworld of living things. The rest ... we have to find out about. Wnt (talk) 01:19, 4 March 2017 (UTC)

Coordinate system of planetary data

The inclination value 89° looks very strange for such synchronized system. What is the coordinate system? It must be not analog of heliocentric coordinates for the central star, but some other coordinates. Anton Kopiev (talk) 18:01, 3 March 2017 (UTC)

The inclinations of exoplanet orbits (and stellar rotation axes) are given relative to our line of sight, where 90 degrees indicates the orbit is exactly along the line of sight. Planets which transit have inclinations near 90 degrees. Dab8fz (talk) 05:49, 6 March 2017 (UTC)

Science Outreach

Science outreach posted on an astronomical project's official website is hardly irrelevant. If the viral LIGO Chirp is relevant, so is this; the graphic novel does a good job of laying out the basic scientific facts, albeit in an anthropomorphic context. kencf0618 (talk) 01:05, 4 March 2017 (UTC)

If it's that educational, then I won't oppose a specific link pointed directly to the graphic novel in the "Further Reading" section. I oppose mentioning in the article body unless reliable independent sources are discussing it. And, I oppose a link to other speculative fiction, or any compilation of speculative fiction, in the "further reading" section because it's not clear that those works are of sufficient educational value and are being factchecked. It is somewhat unusual that the discovery team appears to be publishing SF about their star on their webpage, but I contend that not all of that needs to be linked here. Geogene (talk) 01:09, 4 March 2017 (UTC)

Lack of lithium does itself prove that is a true star. Any object with a mass >0.065 than that of the Sun will burn hydrogen (and lithium) for some time but for it to be a star it needs to be more massive than about 0.072 Sun's masses to sustain this hydrogen burning. Ruslik_Zero 17:01, 4 March 2017 (UTC)

@Ruslik0: I'm not sure why you added this comment here, but since you did, I will reply here. The TRAPPIST-1 article currently says optical spectroscopy fails to detect lithium suggesting it is a main-sequence star rather than a very young brown dwarf. Use of the word suggest follows almost exactly what we find in Gillon et al. 2016. These authors always refer to the star as an "ultracool dwarf", not a red dwarf. Clearly at 0.08 ± 0.009 M☉, it is a borderline case. However, we could add some more details which the Gillon et al. 2016 article lists in support of the idea. --Robert.Allen (talk) 18:27, 4 March 2017 (UTC)

Sorry, the comment was intended for a section above. Ruslik_Zero 18:58, 4 March 2017 (UTC)

I think it's clear that the Google Doodle stuff might be relevant to that page, but it's not relevant to the star itself. A company that makes a quick drawing for any given day's headline shouldn't get a mention in every single Wikipedia article about every single headline from every single day! I haven't decided about the novel yet, but I took the tag off it - we know there's a disagreement and should work it out here, no need to have big ugly tags about a disagreement we already know about. Wnt (talk) 01:31, 4 March 2017 (UTC)

Fair enough. There is an intersection of science outreach, mass media and social media reaction to major scientific discoveries, and Wikipedia policies, after all. kencf0618 (talk) 01:44, 4 March 2017 (UTC)

(ec) OK, I looked at the site -- despite some suggestions above, I so far see no evidence that this site has anything to do with the discovery team. I don't see any "lepithec" on either Nature paper or anywhere else in our references section! Until I see evidence to the contrary, I think this is just some guy who could draw well and realized there was a ".one" TLD with a name to be taken. Now, we could have a link if the site is educational and useful, or properly reference and mention it if it is "notable" i.e. mentioned by secondary sources about TRAPPIST ... so far I'm not greatly convinced. If Lepithec himself is notable (in the Wikipedia policy sense) and has an article anywhere on Wikipedia of course it can be detailed there. Wnt (talk) 01:50, 4 March 2017 (UTC)

Formation

How did 7 near Earth sized objects form around a red dwarf with years that last only a few Earth days? It is not mentioned in the article. It is also not mentioned in the nebular hypothesis page on how such systems could form. Also, why is it not mentioned anywhere of the possibility that "exoplanets/planets" are just evolved/evolving stars and the modern edifice of astrophysics is misguided at best? How (myth)-busted does the nebular hypothesis (and all its variants that assume stars to be mutually exclusive of planets) need to get before it is trashed?Trilliant (talk) 15:21, 8 March 2017 (UTC)

It's probably too early to say much about the formation of the system. Gillon et al 2017 state that the masses and orbital parameters of the seven known planets are too uncertain to permit reliable predictions of the long-term dynamical evolution of the system. However, the simulations they ran did suggest that tidal heating might be strong enough to affect the planets' energy budgets and geological activities. --Robert.Allen (talk) 01:11, 9 March 2017 (UTC)

These objects have measured masses which are far too low to enable fusion in their cores, so they are unambiguously planets. Dab8fz (talk) 20:16, 10 March 2017 (UTC)

Planetary parameters

Yes, the initial discovery of the planets was through the transit method. This technique is not useful for determining the mass of these planets, but usually only their radius. What's missing here is how the mass of these planets was derived. Was this data gathered at the same time? Later? Is it still being refined? Kortoso (talk) 20:57, 9 March 2017 (UTC)

They can determine their mass from the differing time of transit, combined with radial velocity differences. exoplanetaryscience (talk) 23:21, 9 March 2017 (UTC)

Tidal locking and development of life

In the "Tidal locking" section it is written that "All seven planets are likely to be tidally locked (one side of each planet permanently facing the star), making the development of life there "much more challenging... Tidally locked planets would typically have very large temperature differences between their permanently lit day sides and their permanently dark night sides, which could produce very strong winds circling the planets. The best places for life may be close to the mild twilight regions between the two sides, called the terminator line."
The questions are the next:
1) Why tidal locking will produce strong winds? For my opinion, the winds will be formed only when one side is heated (or cooled) at the first time; once the pressures are aligned, the air flow should stop. I.e. if both sides are constantly "hot" and "cold", how the wind can be formed?
2) For my opinion, the best place for life in the case of tidal locking are the dark sides, and not the terminator line. The "dark sides" are not really dark, so as they have several other planets visible in the sky as big "moons", which will illuminate the "dark sides" by a reflected light, which is much brighter than the light from a single Moon in our sky. In addition, the dark sides will be protected from UV and X-ray irradiation, which again makes them a better place for life. Krasss (talk) 22:07, 10 March 2017 (UTC)