Talk:List of exoplanet extremes

Recent changes

I recently changed the record on the most distant exoplanet to be those around SDSS J1004+4112, but this change keep being reverted by reasons that i deem irrelevant. I say these exoplanets will remain, they are valid additions to this list, and if no one gave importance to these planets for so long, six years after they were discovered, I will. 21 Andromedae (talk) 00:42, 5 January 2025 (UTC)

In order to aswer this, I will copy the rest of the conversation from my talk page. There is even (a little) more within the edit summaries comments (the beginning): Stevinger (talk) 13:36, 7 January 2025 (UTC)

I will post here the beginning from the edit summaries (rogue planets part): Stevinger (talk) 22:19, 13 January 2025 (UTC)

22:43, 1 January 2025 21.Andromedae: these are the true most distant exoplanets, even though they are not orbiting any star. Stevinger (talk) 22:21, 13 January 2025 (UTC)

03:26, 3 January 2025 Stevinger: did you see the extragalactic planets page says the SWEEPS ones are the first confirmed ones? Stevinger (talk) 22:21, 13 January 2025 (UTC)

13:20, 3 January 2025 21.Andromedae: ??? Stevinger (talk) 22:25, 13 January 2025 (UTC)

13:37, 3 January 2025 21.Andromedae: Extremes from Earth's viewpoint: Indeed Wikipedia was claiming SWEEPS-11b and SWEEPS-04b to be the most distant exoplanets, but since Wikipedia is not a reliable source, i would not consider this. Also, i removed this claim from there and included these planets as confirmed discoveries. Stevinger (talk) 22:26, 13 January 2025 (UTC)

19:50, 3 January 2025 Stevinger: The rogue planets can also be explained by primordial black holes. Stevinger (talk) 22:26, 13 January 2025 (UTC)

14:08, 4 January 2025 21.Andromedae: The source actually meant to say that some of the objects could be primordial black holes, and other could be free-floating planets. It doesn't mean that all of the objects observed are micro black holes, which would be impossible from a mathematical point of view. Stevinger (talk) 22:28, 13 January 2025 (UTC)

18:37, 4 January 2025 Stevinger: exchanged the most distant again. The rogue planets are not individually confirmed. More important, trusting IAU, the rogue planets do not fulfill the exoplanet definition of IAU. Stevinger (talk) 22:29, 13 January 2025 (UTC)

21 Andromedae to Stevinger on 23:39, 4 January 2025 (UTC): The planets around SDSS J1004+4112 are to be the most distant exoplanets discovered. I don't see why being not "individually confirmed" would be a reason to remove them, and the IAU definition can't be (and is not) strictly followed throughout the entire article, it still has flaws, is incomplete and solar-system centric. Excluding these planets because this definition says they are not, when there is an universal consensus that small rogue planets (less than Jupiter's mass) are planets, won't improve the page. It could be useful to use the IAU definition as a moderator in some cases e.g. when there is no consensus on whether object X is a planet or (sub) brown dwarf, but exceptions might be needed sometimes. Stevinger (talk) 13:38, 7 January 2025 (UTC)

Ok, final round. Back to SDSS J1004+4112: I see your point about 'individually confirmed'. I meant that for none of the objects we can be sure it is a free-floating planet and that we cannot repeat the microlensing event, but it is likely some are free-floating planets, indicating there are some. I also see that you regard low-mass free-floating planets as exoplanets. Here, it is getting interesting again. I am sure this is not universal, since I have read differently. But if you have a few references on this 'universal consensus that small rogue planets (less than Jupiter's mass) are planets', this would be great, because it would improve the Rogue planets page. Until then, yes, I would like to stick to the most commonly used definition of exoplanets on the Exoplanet page saying: 'Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or whatever name is most appropriate).'

If the 'IAU definition can't be (and is not) strictly followed throughout the entire article', then we have to decide whether this is wanted. I used it as reason not to accept Proplyd 133-353 as largest exoplanet, and thus recommend to use it here. Stevinger (talk) 14:51, 7 January 2025 (UTC)

For Proplyd 133-353 it is a different case, as there is not a consensus among astronomers that large, Jupiter-sized planets that could have formed like stars (this is often used as the criterion for distinguishing planets and sub-brown dwarfs), are planets, and, as i said, the IAU definition could be used for these cases, but common sense should dominate. Also, these are the references: [1] [2] [3] [4] [5] [6], as well as the news media and the average reader. 21 Andromedae (talk) 15:33, 7 January 2025 (UTC)

Thank you for the links. I assumed we are using the IAU definition stricly after you put GP Comae Berenices b as most dense, despite it likely formed like a white dwarf. Why I doubt the consensus that small rogue planets are exoplanets is universal is because I read somewhere that as you confirmed heavy free-floating planets could have formed like stars and that small ones (<0.5 MJup) or similar could have formed in disks around the free-floating planets (as such disks are known to exist). Then these secondary objects would have never been in orbit around a star or brown dwarf, as there host object would be a sub-brown dwarf. They don't need to be ejected from star's disks and would not fulfill the current definition of exoplanet either. Yes, this is not clear. Yes, it could be different. But I assumed this is the reason we have a IAU's Commission F2: Exoplanets and the Solar System and why the official working definition of exoplanet is updated from time to time. Stevinger (talk) 18:45, 7 January 2025 (UTC)

It should be reasonable to keep these rogue planets, therefore. 21 Andromedae (talk) 01:07, 8 January 2025 (UTC)

? therefore ? Stevinger (talk) 01:25, 8 January 2025 (UTC)

I understand now, why you wrote therefore, after reading it again. I mixed up sub-brown dwarf with free-floating planet close to the end (likely because they are used so interchangable these days, as IAU also mentioned), what made it almost impossible to understand. I am quite confident you agree high-mass rogue planets could have formed like a star. You mention a 'universal consensus that small rogue planets (less than Jupiter's mass) are planets'. What I meant is, that for a single object you find below a Jupiter mass or so you cannot be sure it formed like a planet either. If it formed around a free-floating planet ejected from a disk, it could be an exomoon. Take e.g. DH Tau Bb. If it is confirmed to exist it is a 1 MJup exomoon. If it is ejected by interaction, ... it seems to be a 1 MJup exoplanet. So for high mass objects you can't be sure if the free-floating planet formed like a star or a planet, for low-mass ones you can't be sure if it formed like a planet or a moon. This seems a decent reason to use the current IAU working definition as suggested in the conclusion topic below. Stevinger (talk) 03:40, 10 January 2025 (UTC)

I will post here the beginning from the edit summaries (stellar remnants part): Stevinger (talk) 21:59, 13 January 2025 (UTC)

20:09, 3 January 2025 21.Andromedae: Stellar characteristics: Neutron stars and white dwarfs are not stars Stevinger (talk) 22:02, 13 January 2025 (UTC)

00:13, 4 January 2025 Stevinger: not a big deal, since it seems clear what the categories are, but why should a neutron star or white dwarf not be a star? Stevinger (talk) 22:03, 13 January 2025 (UTC)

00:44, 4 January 2025 21.Andromedae: That is because neutron stars and white dwarf no longer produce nuclear fusion in their cores, most definitions exclude them as stars. Stevinger (talk) 22:04, 13 January 2025 (UTC)

13:14, 4 January 2025 Stevinger: I have only seen definitions without fusion, yet. I assume the reason is either that compact objects are just part of the stellar evolution or because otherwise protostars and pre-main-sequence stars wouldn't be stars either. Please also see other sources, e.g. https://science.nasa.gov/universe/stars/types/ or e.g. a book on compact objects https://books.google.de/books?id=cCDlBwAAQBAJ&pg=PA1 giving in the introduction, paragraph 2: 'Neutron stars are the smallest, densest stars known.' Stevinger (talk) 22:05, 13 January 2025 (UTC)

14:05, 4 January 2025 21.Andromedae: Stellar characteristics: Leave it the way it is, because that is correct and the way it was is not. Also, see the definition of ESA about a star https://esahubble.org/wordbank/star/. Even the IAU agrees, their definition of exoplanets include "that orbit stars, brown dwarfs or stellar remnants", so the most accurate is to separate neutron stars and white dwarfs from true stars. Stevinger (talk) 22:06, 13 January 2025 (UTC)

18:51, 4 January 2025 Stevinger: To clarify: Stars need to fuse at some point in their life, yes. Your ESA source: 'stars eventually generate sufficient pressure and temperature ... for hydrogen fusion to begin', so objects are stars before. If you click on the 'deaths' link (3rd paragraph), you find: 'The burned-out star, called a white dwarf' in the first paragraph. If you go to https://esahubble.org/wordbank/white-dwarf/ you even find 'a pair of white dwarf stars' in the text. Every currently fusing object is a star, indeed. Stevinger (talk) 22:11, 13 January 2025 (UTC)

18:57, 4 January 2025 Stevinger: I have to correct that. Every currently hydrogen or higher elements fusing object is a star. That does not mean every object not fusing at the moment is not a star. Objects just have to fuse these elements during their lifetime. So ESA, NASA and the book are consistent. The IAU likely emphasized 'stellar remnant' to clarify that second generation planets formed around stellar remnants can be/are planets. This does not mean stellar remnants / compact objects are not part of the stellar evolution. Stevinger (talk) 22:11, 13 January 2025 (UTC)

21 Andromedae to Stevinger on 23:39, 4 January 2025 (UTC): Also, about including stellar remnants as stars, the ESA's definition explictly say that stars need to fuse hydrogen or a heavier element, other minor excerpts or external pages that (barely) contradict the official definition therefore are not relevant. An external page could be written by other person with a different opinion for example. Assuming the IAU discounted them as stars because of X or Y isn't a valid argument as well. I'm not here to discuss whether compact objects are stars or not, but to consider that some definitions agree that degenerate stars are stars, but others not. This mean that the most appropriate way to deal with is to put them into a separate category, and let what "everyone agrees to be a star" in the category of stars, as i tried to did. Stevinger (talk) 13:38, 7 January 2025 (UTC)

21 Andromedae to Stevinger on 00:06, 5 January 2025 (UTC): In short, putting the "quasar microlensing rogue planets" as the most distant planets, and separating stellar remnants from true stars, due to lack of scientific consensus on they being a star are improvements and therefore should not be reverted again. Rather than reverting it back with (weaker) arguments again and again, try to include the possibility that you were wrong all along and that it might be better to just let it go. Also, don't discuss in edit summaries after two replies (or even one), as it might disrupt the edit history and even cause an edit war. Instead discuss in the talk page or in the user's talk page. Stevinger (talk) 13:39, 7 January 2025 (UTC)

I considered to be wrong, that is why it was interesting. Because it would have meant lots of pages are not accurate and would need an update. If stellar remants wouldn't be stars and a star needs to actively fuse hydrogen to be a star, the following pages, likely among others, would have needed an update:

Star: 'A star is a luminous spheroid of plasma held together by self-gravity.', 'A star's life begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and trace heavier elements.', 'A star shines for most of its active life due to the thermonuclear fusion of hydrogen into helium in its core.', 'At the end of a star's lifetime as a fusor, its core becomes a stellar remnant', 'Stellar nucleosynthesis in stars or their remnants creates almost all naturally occurring chemical elements heavier than lithium.'.

Stellar evolution: 'Nuclear fusion powers a star for most of its existence.', 'If a white dwarf forms a close binary system with another star', 'These stars, known as neutron stars'.

White dwarf: 'If a white dwarf star accumulates sufficient material from a stellar companion to raise its core temperature enough to ignite carbon fusion, it will undergo runaway nuclear fusion, completely disrupting it.'

Neutron star: ' Surpassed only by black holes, neutron stars are the second smallest and densest known class of stellar objects', 'Asteroseismology, 'a study applied to ordinary stars, can reveal the inner structure of neutron stars by analyzing observed spectra of stellar oscillations.', 'A neutron star is composed mostly of neutrons (neutral particles) and contains a small fraction of protons (positively charged particles) and electrons (negatively charged particles), as well as nuclei. In the extreme density of a neutron star, many neutrons are free neutrons, meaning they are not bound in atomic nuclei and move freely within the star's dense matter, especially in the densest regions of the star—the inner crust and core. Over the star's lifetime, as its density increases, the energy of the electrons also increases, which generates more neutrons.'

Compact object: 'Although compact objects may radiate, and thus cool off and lose energy, they do not depend on high temperatures to maintain their structure, as ordinary stars do.', 'The stars called white or degenerate dwarfs are made up mainly of degenerate matter', 'In certain binary stars containing a white dwarf', 'there is a limiting mass for neutron stars: the Tolman–Oppenheimer–Volkoff limit, where these forces are no longer sufficient to hold up the star.'

T Tauri star: 'T Tauri stars are pre-main-sequence stars in the process of contracting to the main sequence along the Hayashi track, a luminosity–temperature relationship obeyed by infant stars of less than 3 solar masses (M_☉) in the pre-main-sequence phase of stellar evolution. It ends when a star of 0.5 M_☉ or larger develops a radiative zone, or when a smaller star commences nuclear fusion on the main sequence.'

Protostar: 'A protostar is a very young star that is still gathering mass from its parent molecular cloud.', 'The phase begins when a molecular cloud fragment first collapses under the force of self-gravity and an opaque, pressure-supported core forms inside the collapsing fragment. It ends when the infalling gas is depleted, leaving a pre-main-sequence star, which contracts to later become a main-sequence star at the onset of hydrogen fusion producing helium.'

Pre-main-sequence star: 'A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.' Stevinger (talk) 14:13, 7 January 2025 (UTC)

Back to the sources / references:

I thought NASA including the objects would help https://science.nasa.gov/universe/stars/types/

There are also books on compact objects https://books.google.de/books?id=cCDlBwAAQBAJ&pg=PA1 (edited by experts from NA and Europe) giving in the introduction, paragraph 2: 'Neutron stars are the smallest, densest stars known.' Not a missed sentence, as followed by: 'Like all stars, neutron stars rotate ...'

The IAU states indeed: 'that orbit stars, brown dwarfs or stellar remnants' in their definition. However, one could say something happens to Humans, animals or children as analogon. This emphasizes it happens or happens in a special way to children, but does not mean children are no humans.

ESA says: 'A star is an approximately spherical body of plasma, which is held together by its own gravity and prevented from collapsing by the energy generated inside it by the fusion of hydrogen into helium.' but it is followed few sentences later by: 'Unlike planets, stars eventually generate sufficient pressure and temperature at their core for hydrogen fusion to begin.' Yes, stars need to fuse at some point, otherwise planets could be stars.

Not sure what you mean by external page regarding ESA. You emphasize 'ESA's definition' on https://esahubble.org/wordbank/star/.. Yes, the page saying 'The burned-out star, called a white dwarf' in the first paragraph is in the news section at https://esahubble.org/news/heic0703/, but the one saying 'a pair of white dwarf stars' in the text is on the very same wordbank: https://esahubble.org/wordbank/white-dwarf/ all on the ESA page.

So, I disagree to 'separating stellar remnants from true stars, due to lack of scientific consensus', as there seems to be no disagreement among sources. (The only source I could find fast stating differently was a Forbes article in which Forbes says it is only the opinion of the author it does not represent Forbes.) If you have additional sources saying stellar remnants are no stars, it will get very interesting and we need to change a lot. Stevinger (talk) 14:37, 7 January 2025 (UTC)

See space.com, National Geographic, coolcosmos.edu and BBC all of which use determinants for stars that exclude stellar remnants. These other Wikipedia pages may be improved in the future. 21 Andromedae (talk) 16:41, 7 January 2025 (UTC)

You might have to give a direct example. I read major parts of the first two and can't find your example.

The National Geographic seems to rather support my points: 'a star enters what is known as the relatively brief T Tauri phase. (next paragraph) Millions of years later, when the core temperature climbs to about 27 million degrees Fahrenheit (15 million degrees Celsius), nuclear fusion begins.', so objects are stars before fusion. 'The red giant phase is actually a prelude to a star shedding its outer layers and becoming a small, dense body called a white dwarf. White dwarfs cool for billions of years. Some, if they exist as part of a binary star system, may gather excess matter from their companion stars until their surfaces explode, triggering a bright nova.' They 'become' white dwarfs and these can be part of a binary star system. If you click on the link on white dwarf btw National Geographic explains that (white dwarfs) 'These ancient stars are incredibly dense'.

Space.com was given first written by an astrophysicist. Here I found what you might have meant: 'Armed with the Hertzsprung-Russell diagram, we can see what truly defines a star: it's an object that lives on the main sequence of that diagram. It's an object that burns hydrogen and steadily evolves along that narrow strip connecting its brightness to its temperature. Things that exist outside that strip are either giants attempting to fuse heavier elements in a futile attempt to stay burning, or dead and decaying remnants like white dwarfs and neutron stars.' However, a paragraph before it says: 'Once hydrogen fusion ends inside of the core of a star, it moves off the main sequence and evolves in different directions. Large stars become red giants, which occupy their own positions on the Hertzsprung-Russell diagram. Other stars might zigzag back and forth, alternating between blueness and redness as heavy elements attempt to fuse deep in their hearts.'. Earlier also ' Instead there is a stripe running diagonally that the vast majority of stars live on. This stripe runs from the dim, red end to the bright, blue end. (new paragraph) This stripe is known as the main sequence, and stars that burn hydrogen in their cores (the primary fuel source for the vast majority of a star's life)'. What is likely meant by 'truly defines' is not that they currently fuse, but that are able to fuse in their life, which is nicely explained by the original definition given much earlier: 'First off, a decent enough astrophysical definition of a star is: any object that is sufficiently massive that it can ignite the fusion of elements in its core due to the gravitational pressures inside the object itself.' This is fulfilled by any star, just born or cooled all the way down it could cool so far (age of universe).

I just read the first two, also just partly. But they don't contradict that stellar remnants are stars. I do this because given above 'These other Wikipedia pages may be improved in the future.', but changing them to say stellar remnants are not stars would not improve them! Stevinger (talk) 19:14, 7 January 2025 (UTC)

As i said, what matters is what the page explictly. Whether some other page in the same domain is treating substellar objects as stars is not really relevant, these pages could have been written by other persons. Also, white dwarfs can't fuse elements in their core, so they don't fullfy the definion of stars given by these sources, that is obvious, so they DO CONTRADICT that stellar remnants are stars, this is obvious as well. 21 Andromedae (talk) 01:14, 8 January 2025 (UTC)

Do you really think National Geographic ('star ... millions of year later ... nuclear fusion begins') and Space.com ('once hydrogen fusion ends ... other stars zigzag back and forth', 'stars that burn hydrogen in their cores (the primary fuel source for the vast majority of a star's life') would have contradicting passages with regard to their definition of star in the very SAME article (no external page citations here)? The definition does not contradict that stellar remants are stars is what is obvious for me. Stevinger (talk) 02:37, 8 January 2025 (UTC)

The "children" example is not valid, as denying the antecedent can be either valid or invalid, in this case is valid, but in other cases it may not. Anyway, this is not what i wanted to discuss, but to note that many sources will not consider stellar remnants as stars and distinguishing both classes is therefore necessary. 21 Andromedae (talk) 16:53, 7 January 2025 (UTC)

I am not saying they should't be distinguished. If you tell me stellar remnant you don't talk about T Tauri stars. If you tell me star, you could talk about stellar remnants or T Tauri stars. Stevinger (talk) 19:19, 7 January 2025 (UTC)

I am writing so much btw because you are a very active user, which is great. And also because the link you recommended me says: 'Many editors ... forget this aspect of the core Neutral Point of View policy, often interpreting "neutral" as "no judgement". Wikipedia founder, Jimmy Wales, stated early in the project development that presenting all views as equal is not the goal of Wikipedia.' Stevinger (talk) 14:40, 7 January 2025 (UTC)

I think this discussion should just die, and my changes should be in the article. 21 Andromedae (talk) 15:36, 7 January 2025 (UTC)

Jumping in here to point out that's not how wikipedia works. Decisions are made based on consensus. I recommend both of you having a look at WP:CONTENTDISPUTE if you can't reach an agreement yourselves. Editing the article to make the changes being debated, without consensus, could be considered edit warring. Ultraodan (talk) 15:55, 7 January 2025 (UTC)

Answer striked. 21 Andromedae (talk) 16:05, 7 January 2025 (UTC)

A third opinion appear to be the best since a consensus can't be achieved, or simply one side could give up and search other pages to edit. 21 Andromedae (talk) 16:19, 7 January 2025 (UTC)

After reading your answers, I am also not sure if we can still solve this alone in a consensus. I was previously more optimistic and was not trying to get you upset. So, if you don't want 'to give up' (I don't think you meant your sentence this way), then please feel free to get running any open third opinion procedure wikipedia usually uses. Stevinger (talk) 19:27, 7 January 2025 (UTC)

Listing this at WP:3O sounds good, I'll leave it for one of you to list. Ultraodan (talk) 06:34, 8 January 2025 (UTC)

it is listed. Stevinger (talk) 04:31, 14 January 2025 (UTC)

Response to third opinion request:

We would use the definitions that you'd find in a standard astronomy textbook. The IAU definition characterizes the mainstream scientific consensus as to the definition of exoplanets, which excludes rogue planets:

The current working definition of an exoplanet, as amended in August 2018 by IAU Commission F2 “Exoplanets and the Solar System”, reads as follows: Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars, brown dwarfs or stellar remnants and that have a mass ratio with the central object below the L4/L5 instability (M/Mcentral<2/(25+621)≈1/25) are “planets”, no matter how they formed. The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System, which is a mass sufficient both for self-gravity to overcome rigid body forces and for clearing the neighborhood around the object’s orbit. Manuductive (talk) 11:57, 21 January 2025 (UTC)

@Stevinger I noticed that you re-posted your Active Disagreement to WP:Third opinion. Please let me know if there was something missing from my comment. Or, if you are interested in hearing what more people have to say, perhaps you could consider tagging this page with a Request for comment. Manuductive (talk) 05:58, 22 January 2025 (UTC)

@Manuductive thank you for asking and writing a response/third opinion on rogue planets. There was an additional disagreement whether neutron stars and white dwarfs are stars, why I re-posted it (without the rogue planets). @21.Andromedae just wrote: 'There are good sources suggesting stars need to have nuclear fusion at their core, and some good sources suggesting the opposite. Therefore it is needed to make a distinction between what is considered a star (red dwarf, G-type star, red giant...), and what is sometimes considered a star (degenerate stars), for making everything secure and neutral.' I argue this seemingly existing ambiguity what a star is is not existing, that stars do not presently have to fuse and that pre-main-sequence stars, main-sequence stars, red giants, white dwarfs and neutron stars are all types of stars. A third opinion would be helpful, thank you. Stevinger (talk) 17:54, 22 January 2025 (UTC)

References

Conclusion?

Thefore, should the current "most distant" planets (SWEEPS-11 and SWEEPS-04) be exchanged to those around the pulsar SDSS J1004+4112, and a difference between stars and stellar remnants be treated as distinct in the "Stellar charactetistics" section? I honestly think yes, and for the latter, there are a plenty of sources that also make this distinction, while for the former, i think all the reasons given for not adding this planet are now gone. 21 Andromedae (talk) 16:30, 8 January 2025 (UTC)

Of course, if you have 5 lines to explain to a person asking what a star is you start to explain the average star and how similar it is to the Sun as happened here. - Please see above a detailed response if anyone wants to read it, I tried to convince 21.Andromedae. - I read e.g. your source of National Geographic. And it is nicely consistent with stellar remnants being stars ( 'The red giant phase is actually a prelude to a star shedding its outer layers and becoming a small, dense body called a white dwarf.', 'Stars spend 90 percent of their lives in their main sequence phase'). I personally think we should trust NASA, listing them as star types (https://science.nasa.gov/universe/stars/types/) and an approximately 400 page book on stellar remnants/compact objects (https://books.google.de/books?id=cCDlBwAAQBAJ&pg=PA1 (edited by experts from NA and Europe) giving in the introduction, paragraph 2: 'Neutron stars are the smallest, densest stars known.' Not a missed sentence, as followed by: 'Like all stars, neutron stars rotate ...') more than reading a definition of them out of the media trying to explain what a star is in general or what a stellar remnant is.

The objects around SDSS J1004+4112 are either rogue planets or primordial black holes, likely a mixture of it, possibly more of them being rogue planets. According to the IAU working definition of exoplanet rogue plaents/free-floating planets are currently not exoplanets. They or parts of them might be in the future if the definition is adapted, but they also might not if additional knowledge might suggest otherwise. (At least the reason of not being a planet according to the working definition is still there). Stevinger (talk) 01:09, 9 January 2025 (UTC)

I just say:

• What the source says explicitly is more important than what it says implicitly. The quoted paragraphs actually contradict that stellar remnants are stars. Stellar remnants do not have life on the main sequence. I also don't think we should give preference to some sources and instead maintain a neutral point of view.
• The IAU definition isn't is an absolute truth. What is said by the IAU has been already ignored to classify what is a dwarf planet, in favour to more up-to-date sources, and i think this should be applied here as well. Instead of relying on their incomplete and solar-system centric definition, we should define what is a planet based on the consensus in most sources: If the majority of sources classify X as a planet, treat X as a planet. If IAU said X is not a planet, ignore it in favour to the majority of sources. If there is no consensus among sources, or if none classify X as a planet, however, it become valid to use the IAU definition. In short, it is unfair to remove an object from the list because a single definition says it is not a planet.

21 Andromedae (talk) 13:40, 14 January 2025 (UTC)

• You are again mixing up things. Your first example from space.com written by an astrophysicist says: 'First off, a decent enough astrophysical definition of a star is: any object that is sufficiently massive that it can ignite the fusion of elements in its core due to the gravitational pressures inside the object itself.' If you can name a white dwarf or neutron star that didn't fuse on the main-sequence then I am impressed. I do not say we should not consider some sources (some are just more clear than others in their statements). None of your sources contradicts that neutron stars and white dwarfs are stars. Some sentences seem to, but they are actually not. As you only give full sources, no paragraphs or even lines you mean, it is very hard to discuss on the topic. All sources above (given) are consistent is my point. A neutral point of view is good, but from the link you send me: 'Many editors, especially new ones, forget this aspect of the core Neutral Point of View policy, often interpreting "neutral" as "no judgement". Wikipedia founder, Jimmy Wales, stated early in the project development that presenting all views as equal is not the goal of Wikipedia'.
• Sure, the IAU working definition is called working definition because it will be updated, as already happened. Interesting you give a Solar System example, as the definition is too 'solar-system centric' in your point of view. In the topic above you gave me 6 examples of publications that deal with free-floating planets. However, all 6 are from microlensing surveys. Even if all microlensing publications would accept free-floating planets as exoplanets IAU's Commission F2: Exoplanets and the Solar System has to consider thousands of other publicaitons for their working definition. I think this working definition should be used for now. But even if I follow your arguments 'If there is no consensus among sources ... it become valid to use the IAU definition', you should agree that there is no consensus among all thousands of publications and exoplanet (sub)communities. You can't even claim the majority thinks your way. This is why a working definition is helpful, it clarifys the current state of consensus (in the ideal case). Btw, you say it is unfair, but I did not remove a single object from the list because the definition says it is not a planet, but 'Rogue planets around SDSS J1004+4112' (as given). Each of them could be a primordial black hole or a free-floating planet and the microlensing event cannot be repeated. Stevinger (talk) 03:50, 15 January 2025 (UTC)

  • Stellar remnants do not have a main sequence life and don't fuse heavier elements; except National Geographic, all sources i gave (including space.com) use the present tense, they imply a star must be fusing hydrogen in the present. Hence stellar remnants are not star, they are not fusing.
  • It is definitively not ideal to disregard a low-mass free-floating planet, while a star stripped to its bare core should be considered one. I am against defining a planet based on a single definition, instead base it on the consensus among sources, if most sources consider X as a planet, it is a planet, and vice-versa. Actually, i believe this list could also consider all planetary-mass objects in the NASA Exoplanet Archive; this list is closely related to the archive and its significance justify this privilege. Their definition would also consider objects closer to a massive planet than a brown dwarf or star, e.g 2M1207b.

  21 Andromedae (talk) 14:29, 19 January 2025 (UTC)

  • Your first statement is wrong. Space.com defines stars as 'First off, a decent enough astrophysical definition of a star is: any object that is sufficiently massive that it can ignite the fusion of elements in its core due to the gravitational pressures inside the object itself.' No time frame given here. The source does NOT imply stars must be fusing hydrogen in the present. On the contrary it says: 'and stars that burn hydrogen in their cores (the primary fuel source for the vast majority of a star's life' Please don't run in circles with already answered questions/statements.
  • What counts as a planet is difficult. E.g. a low-mass brown dwarf could be stripped of some material and then be a regular planet. Or don't you agree on that? Or do you? There are borderline cases like 2M1207b, for which we simply might not know enough to know what it is. Then a definition is helpful, why not use the IAU working definition. You write 'this list could also consider all planetary-mass objects in the NASA Exoplanet Archive; this list is closely related to the archive and its significance justify this privilege.' Let's follow this idea then, to consider what NEA considers. Please see the Exoplanet Criteria of the NASA Exoplanet Archive that has the privilege of being trusted. It states as second criterion 'The planet is not free floating'. I suggest we follow this.

  Stevinger (talk) 02:54, 20 January 2025 (UTC)

  To clarify, a stellar remnant doesn't have a main sequence lifetime; its lifetime starts after its progenitor fades away. And to sum up everything, there is a collection of excerpts of the sources above, suggesting stellar remnants are no stars:

  From BBC:
  

  Stars get their energy from fusion [...] hydrogen atoms fuse together to fuse helium, helium atoms to carbon etc., remnants do not fuse.
  stars eventually begin to run out of hydrogen in their cores, remnants don't run out of hydrogen.
  

  From Sky and Telescope: A star is formed mostly of hydrogen and helium, and neutron stars are just made up of neutrons, while white dwarfs are neutrons and unbound atomic nuclei.
  I would also cite a dictionary of physics that state stars generate nuclear energy, that is, energy via nuclear fusion at their core. As stated above, remnants of stars can't fuse. Another definition alleged to have been researched over 200M research papers also say that stars are hot balls of gas that generate energy.

  21 Andromedae (talk) 14:43, 19 January 2025 (UTC)

  Neutron stars and white dwarfs are indeed not on the main-sequence. But all of them were, so had time on it.

  BBC (beginners guide stars): 'stars eventually begin to run out of hydrogen in their cores'. This already happened to the stars that are neutron stars and white dwarfs. Yes, they do not fuse hydrogen anymore.

  Sky and Telescope: Neutron stars do not consist solely of neutrons (please see Neutron star#Structure or neutron star cross-section).

  Dictionary of physics (quick reference): This is a two line quick reference. Nuclear fusion isn't the only way to generate energy. Yes neutron stars and white dwarfs do not fuse hydrogen anymore.

  One more definition: This is as you write an alleged review of 200M research papers. While a task with a lot of potential to help, this is an AI project. One of the strongest weak points of AIs is that it is not very helpful with references. In the past AI were regularly creating fake references when asked to add some to text. Please provide few research paper references that describe stars as hot balls of gas that generate energy if you are convinced it is reliable.

  I would like to summarize that you claim sources 'imply' a star must be fusing hydrogen in the present, while the source (space.com) says at least in one occasion differently ('and stars that burn hydrogen in their cores (the primary fuel source for the vast majority of a star's life' ). And that several sources are 'suggesting' neutron stars and white dwarfs are no stars (from semantics; we were speaking about these two kinds of objects!). I provided an expert source (~400 page book on stellar remnants/compact objects https://books.google.de/books?id=cCDlBwAAQBAJ&pg=PA1 (edited by experts from NA and Europe)) giving in the introduction, paragraph 2: 'Neutron stars are the smallest, densest stars known.' Not a missed sentence, as followed by: 'Like all stars, neutron stars rotate ...'. Please provide a reliable source that this is not the case, if you still consider neutron stars and white dwarfs not to be stars. Stevinger (talk) 04:05, 20 January 2025 (UTC)

  There are good sources suggesting stars need to have nuclear fusion at their core, and some good sources suggesting the opposite. Therefore it is needed to make a distinction between what is considered a star (red dwarf, G-type star, red giant...), and what is sometimes considered a star (degenerate stars), for making everything secure and neutral. I gave a rather good source, that is, the ESA Definition, as well as other sources that are still reliable. I would consider that degenerate stars aren't actually their progenitor (which would imply that they have never been main sequence, subgiant...), they are just what's left, the rest of the star faded away in the supernova or planetary nebula, and is now making Earth's elements. 21 Andromedae (talk) 11:51, 22 January 2025 (UTC)

  You are contradicting yourself a bit and seem to accept that ESA contradicts themselves. Let me try to explain:

  You talk about sources suggesting stars need to have nuclear fusion at their cores and give red giants as example of fully accepted stars. If you go to the Red giant page you find there three different types of stars. Two of them (red-giant branch stars and AGB stars) do NOT fuse in their core, but in shells around inert cores. This is a good example why you can't take any source for what a star is as a word by word definition.

  The ESA definition as you call it speaks of fusion of hydrogen into helium. This would mean again that parts of the red giants fusing e.g. helium are not stars according to how you understand it. In addition they write: 'Unlike planets, stars eventually generate sufficient pressure and temperature at their core for hydrogen fusion to begin.' This shows that stars are stars before they fuse hydrogen, again not consistent with how you understand ESA.

  There is an easy solution to this. The ESA definition as you call it says: 'A star is an approximately spherical body of plasma, which is held together by its own gravity and prevented from collapsing by the energy generated inside it by the fusion of hydrogen into helium.' This sentence says stars need to be able to fuse hydrogen into helium. But is does NOT say they need to do it right now. This allows pre-main-sequence stars (fusing in the future), red dwarfs and G-type stars (fusing right now), red giants (partly fusing right now or fusing higher elements), white dwarfs and neutron stars (stopped to fuse) all to be stars. I am not saying any of the references (especially ESA) are unreliable, but non of your references contradicts that all of these stars in the previous sentence are stars!

  Just for completeness: No, white dwarfs and neutron stars are not progenitors to main-sequence stars. Not sure, what you mention there. Stevinger (talk) 17:38, 22 January 2025 (UTC)

  For red giants, fusing in outer shells would be analog to fusing in the inner core, this does not mean red giants aren't stars either according to the ESA definition. Straw man arguments aside, ESA's sentence quoted in bold imply a star is fusing hydrogen now; this can be easily inferred by the present tense used: prevented from collapsing by the energy generated inside it by the fusion of hydrogen into helium., they are saying the fusion occuring in the core prevent it from collapsing; otherwise the star would implode because of gravity, and degenerate stars can't fuse. 21 Andromedae (talk) 23:27, 22 January 2025 (UTC)

  Well, it might imply a lot. But would you e.g. conclude from a sentence, 'a balloon is prevented from collapsing by air or helium sealed inside.', that only an inflated balloon is a balloon or only more precisely a sealed one? I still don't understand why you try to read what is implied to be a white dwarf or a neutron star according to ESA from the star page, instead of directly going to the corresponding pages of ESA: 1) White dwarf: 'Earth-like planets in the atmospheres of a pair of white dwarf stars' or 'In 2006 Hubble was the first telescope to directly observe white dwarfs in globular star clusters, which astronomers reported as the dimmest stars ever seen in a globular star cluster.' 2) Neutron stars: 'Due to extreme pressure, the electrons and protons present in normal matter fuse together with the result that these exotic stars are composed almost entirely of neutrons.' or 'In 1997 Hubble provided the first direct look, in visible light, at an isolated neutron star. The telescope’s results showed the star is very hot (670 000 degrees Celsius at the surface)'. This is consistent with NASA star types including white dwarfs and neutron stars. Stevinger (talk) 09:08, 23 January 2025 (UTC)

Now i think it's time to send checkmate. If all stellar remnants are stars according to your argument, then stellar black holes are also stars, as they were generated when a massive star die. Imagine this, a black hole being considered a star. 21 Andromedae (talk) 22:47, 14 January 2025 (UTC)

We were talking about neutron stars and white dwarfs, after you wrote: '20:09, 3 January 2025 21.Andromedae: Stellar characteristics: Neutron stars and white dwarfs are not stars'. Followed by the introduction of stellar remants by you: '14:05, 4 January 2025 21.Andromedae: Stellar characteristics: ... Even the IAU agrees, their definition of exoplanets include "that orbit stars, brown dwarfs or stellar remnants", so the most accurate is to separate neutron stars and white dwarfs from true stars.' and soon later: '21 Andromedae to Stevinger on 23:39, 4 January 2025 (UTC): Also, about including stellar remnants as stars ...'. I admit to maybe being lazy writing 'stellar remnants' instead of 'neutron stars and white dwarfs' following your example, but I did not claim that all stellar remnants are stars. That was just now introduced by you and then used as a new argument. Stevinger (talk) 04:16, 15 January 2025 (UTC)

Your argument in past edit summaries was that a star just need to fuse elements in its lifetime, not to fuse in the present. If so, a stellar black hole is a star, because it used to fuse hydrogen in the past. 21 Andromedae (talk) 14:34, 19 January 2025 (UTC)

I wrote: 'To clarify: Stars need to fuse at some point in their life, yes. Your ESA source: 'stars eventually generate sufficient pressure and temperature ... for hydrogen fusion to begin', so objects are stars before. If you click on the 'deaths' link (3rd paragraph), you find: 'The burned-out star, called a white dwarf' in the first paragraph.' Any object needs to have enough mass to be able to fuse hydrogen at some point to qualify for a star (brown dwarfs e.g. don't). You told me how the name is in wikipedia: denying the antecedent. This is not the same as any object that fused hydrogen is a star. See e.g. the last paragraph of Stellar evolution#Supernova. Objects can leave behind no black hole remnant. These objects are then an example for being no star, while they used to fuse hydrogen. Again, we were talking about neutron stars and white dwarfs as examples of stars. Stevinger (talk) 02:34, 20 January 2025 (UTC)

The IAU definition that Wikipedia should use for exoplanets specifically says that exoplanets orbit stars, brown dwarfs or stellar remnants. If it's agreed that white dwarfs and neutron stars are "stellar remnants", then it seems extraneous to this talk page to discuss whether they're also "stars". Manuductive (talk) 05:59, 23 January 2025 (UTC)

@Manuductive Yes, it seems extraneous. But the categories under 'Title' in the list in the stellar characteristics section are the problem. @21.Andromedae suggested categories I regard as misleading and I suggested categories 21.Andromedae regarded misleading (Mine were e.g. 'Hottest star with a planet' and 'Hottest non-compact star with a planet', which is wrong if pulsars aren't stars). Even trying to find a neutral version would likely just shift the disagreement to another page's talk page or might have led to a lot of changes. Stevinger (talk) 09:22, 23 January 2025 (UTC)

I'd be interested if you could list the categories that you each are proposing. The mainstream scientific consensus seems to put stellar remnants in a distinct category from stars. The IAU glossary states that A star is a ball of plasma – atomic nuclei separated from their electrons – that is held together by its own gravity, and prevented from collapse by inner pressure that is the consequence of nuclear fusion processes in the star's core regions.. It goes on to say that the word "star" is taken to include ... stellar remnants (emphasis added), but that seems to just be an acknowledgement of the common usage, which differs from the scientific usage. The glossary entry for "stellar remnants" clearly states that Stellar remnants are very compact compared to stars. This suggests that IAU does not consider stellar remnants to be "stars". Manuductive (talk) 11:56, 23 January 2025 (UTC)

@Manuductive Thank you for the IAU link. I am, however, fairly convinced it is the other way round.

But first things first. Stellar remnants in general are unlikely considered to be stars, as they contain stellar black holes. This is why the orbit stars, brown dwarfs or stellar remnants in the IAU definition is important. Otherwise blanets around black holes, if they are found, would not be planets according to definition.

As said I am fairly convinced the general "star" definition in the IAU link is the scientific usage one and the fusion version is the common one. Reason:

• General "star" version is e.g. present in: A) Textbooks on stellar remnants: Introduction, paragraph 2: 'Neutron stars are the smallest, densest stars known.' Not a missed sentence, as followed by: 'Like all stars, neutron stars rotate ...'. B) ESA glossary and press releases: 'Due to extreme pressure, the electrons and protons present in normal matter fuse together with the result that these exotic stars are composed almost entirely of neutrons.' or In 1997 Hubble provided the first direct look, in visible light, at an isolated neutron star. 'The Hubble results show thestar is very hot (1.2 million degrees Fahrenheit or about 670 thousand degrees Celsius at the surface)'. C) NASA press releases and star type pages: The corresponding NASA press release: 'The Hubble results show the star is very hot, and can be no larger than 16.8 miles (28 kilometers) across.'. Neutron stars and white dwarfs are included as star types in the star type pages.
• Fusion version is e.g. present in: A) Most kinds of news organizations: BBC beginners guide stars or Sky and Telescope. B) Dictionaries: dictionary of physics. C) Star in a Wordbank/Glossary: ESA or IAU.

The space.com article by an astronomer shows the situation nicely. On the one hand it says: 'we can see what truly defines a star: it's an object that lives on the main sequence of that diagram. It's an object that burns hydrogen and steadily evolves along that narrow strip connecting its brightness to its temperature.' This is good, because a non-fusing planet cannot be a star. However, fusion is not unique among objects. Brown dwarfs can fuse deuterium and some lithium. And another thing is different, they only fuse in a tiny part of their lifetime. It is not good to define an object is currently fusing, otherwise the vast majority of brown dwarfs wouldn't be brown dwarfs (not fusing at the moment). That a definition is better based on another property also for stars is shown in the space.com article, as the astronomer gives a real definition almost right at the beginning: 'First off, a decent enough astrophysical definition of a star is: any object that is sufficiently massive that it can ignite the fusion of elements in its core due to the gravitational pressures inside the object itself.' If defined by mass being sufficient there are no problems with brown dwarfs fusing only a tiny part of their lifetime and for stars: Protostars are massive enough that they fuse in the future, some stars fuse right now, white dwarfs and neutron stars are massive enough that they fused in the past (indeed few exceptions exist also for this definition).

@21.Andromedae is probably right, that most likely the majority of sources have the fusion version, as news articles and dictionaries will likely be more in number. - Or one could try hard to find neutral categories for this list. - I was pushing for the general "star" version, as it is the scientific usage one. If this is not the goal for wikipedia, then I was indeed 'wrong all along'. Please recommend what to use. Stevinger (talk) 05:53, 24 January 2025 (UTC)

You might be doing a bit of Wikipedia:Synthesis there. Here is a good source by Ethan Siegel that gives a conclusive answer: https://medium.com/starts-with-a-bang/neutron-stars-white-dwarfs-brown-dwarfs-and-more-arent-actually-stars-ef24b8959b94 Manuductive (talk) 13:35, 24 January 2025 (UTC)

I see your points. I know the newer publication of the same topic of Ethan Siegel in Forbes. I actually counted these in the widest sense to news organizations, as Forbes even states 'Opinions expressed by Forbes Contributors are their own'. Siegel also published similar articles 'Surprise: the Big Bang isn’t the beginning of the universe anymore', which was at least partly critizised for its reasoning (and being closer to his PhD in theoretical cosmology). I suggest to instead consider the work of a scientist, that unfortunately recently passed away, Norman K. Glendenning. I emphasize it is not about credentials, but about experience in the field of neutron stars and white dwarfs. While Ethan Siegel worked mostly on cosmology, Glendenning had about 45 publications on Neutron stars. In a recent, how do you say, epitaph Norman K. Glendenning was praised by the American Institute of Physics as follows:

'During his long and fruitful career, he repeatedly defined new directions of research in the overlapping areas of nuclear physics and relativistic astrophysics. He was the first to propose the existence of a solid crystal in the core of neutron stars, consisting of a mixture of quark and hadronic matter. This mixed phase might account for such observed phenomena as “starquakes” in pulsars and could even cause isolated neutron stars to spin up rather than spin down. Based on detailed numerical studies, Norman and collaborators were able to predict several astrophysical signals that could signal the existence of quark matter in the centers of neutron stars. These signals are detectable with radio telescopes and x-ray satellites and have attracted tremendous interest in the physics and astrophysics community. The notion quark astronomy has been coined in the literature for this kind of research.'

This person wrote the 389 pages book I earlier mentioned, which series is edited by 6 other scientists, partly being directors of astrophysical institutions in Europe and USA. It says about the objects of interest:

Neutron stars: Page 1: 'Neutron stars are the smallest, densest stars known.' and 'Like all stars, neutron stars rotate ...'. Page 3: 'The constituents of neutron stars - leptons, baryons and quarks - are degenerate. They lie helplessly in the lowest energy states available to them. They must. Fusion reactions in the original star have reached the end point for energy release - the core has collapsed and the immense gravitational energy converted to neutrinos has been carried away. The star has no remaining source of energy to excite the fermions. Only the Fermi pressure and the short-range repulsion of the nuclear force sustain the neutron star against further gravitational collapse - sometimes.'

White dwarfs: Page 57: 'white dwarf, a star whose high surface temperature (8000 K) makes it appear white.'

There are other examples, but this is getting too long. This book on compact stars clearly contradicts Ethan Siegel's articles. Based on the much larger experience of Norman K. Glendenning in the field of compact stars and the 6 editors of this series not objecting to publish it this way, I recommend to trust this book (also consistent with NASA and ESA press releases, star type pages, ... the IAU general sense "star" term, ...). Stevinger (talk) 04:43, 25 January 2025 (UTC)

You make a good case for there being more of a scientific consensus around the broader definition. Encyclopedia Britannica says the white dwarf is a "faint star"[7] and the neutron star is a "compact star".[8] I posted an announcement about this discussion at Wikipedia_talk:WikiProject_Astronomical_objects#Classification_of_rogue_planets,_white_dwarfs,_and_neutron_stars Manuductive (talk) 12:04, 25 January 2025 (UTC)

We ended up getting a decent reply over at that thread. Manuductive (talk) 16:29, 27 January 2025 (UTC)

I suggest considering the opinions of both scientists rather than a single one; Wikipedia don't take sides except in very specific cases. 21 Andromedae (talk) 17:45, 26 January 2025 (UTC)

please see: Wikipedia does pass judgement Stevinger (talk) 13:40, 27 January 2025 (UTC)

This page say If a view is the majority view of a broad consensus of scientists, then we say so. This is not the case for when there is some people say a thing, other people say another in similar quantity (the exact situation about degenerate stars being stars); an example of where it would be valid is about not considering Pluto a planet. 21 Andromedae (talk) 16:59, 27 January 2025 (UTC)

The page also says 'If a view is a minority view of some scientists, scientists who are respected by the mainstream that differs with them on this particular matter, then we say so. And if a view is held only by a few people without any traditional training or credentials, and if that view is dismissed by virtually all mainstream scientists, then we can say that, too.' Is there any other source than Ethan Siegel that white dwarfs and neutron stars are not stars? (not implied or suggested by sentences, but clear sources) Stevinger (talk) 22:34, 27 January 2025 (UTC)

There are also other scientists suggesting stellar remnants are not stars, the Britsh Astronomical Association says a star spent most of its life as a main sequence star, de-classifying degenerate stars to be stars. Furthermore, well-known dictionaries like the Cambridge Dictionary and the Collins Dictionary also use fusing hability of stars to classify them as such, their definition is less accurate, "burning gas" instead of "fusing plasma", but still imply a star fuse elements, with the use of the present tense showing it is fusing now. 21 Andromedae (talk) 17:59, 26 January 2025 (UTC)

White dwarfs are even shown in the single plot presented in the 'What is a star?' of Britsh Astronomical Association.

Collins Dictionary: 'star ... radiates energy ... usually derived from thermonuclear reactions in the interior'. Collins Dictionary: White dwarf: 'white dwarf ... one of a large class of small faint stars of enormous density ... It is thought to mark the final stage in the evolution of a sun-like star'. Collins Dictionary: Neutron star: 'neutron star ... a star that has collapsed under its own gravity to a diameter of about 10 to 15 km.' Stevinger (talk) 13:48, 27 January 2025 (UTC)

This strengthes the case of where there is no consensus about their classification, and considering "stars" only what all (or the majority of) sources consider to be stars would be the most appropriate. White dwarfs were added in the plot because they're relevant for stellar evolution, that doesn't necessarily mean they are considering white dwarfs to be stars. As i said before, most of these sources aren't written by a single person, and people with different opinions can wrote dictionary entries. 21 Andromedae (talk) 17:07, 27 January 2025 (UTC)

No, it does not. If Collins says usually derived from reactions and the definition of white dwarf and neutron star in Collins is a star, then there is a clear consensus in this source they are stars.

Yes, white dwarfs in the plot not necessarily means white dwarfs are stars, equally your reason (90% of objects on main-sequence, time on main sequence, ...) does not mean white dwarfs are no stars. Stevinger (talk) 22:40, 27 January 2025 (UTC)