Talk:WR 104

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Looking for subject-matter expert: Opening angle?[edit]

I want to add this text to clarify the analysis:

"The Earth would only be in danger if the actual angle of the star's pole relative to the Earth is less than half the opening angle."

Can a subject-matter expert confirm that that statement is obviously accurate to an astronomer, that is, "opening angle" doesn't have some weird and different meaning in astronomy than it does in geometry?

Rolf H Nelson (talk) 21:49, 20 December 2015 (UTC)

HI Rolf

I don't have a wiki edit account (no time unfortunately) so will reply like this. Note that I work in quite a few different fields, and the WR stars have taken a back seat over recent years so I am not fully up do date with the latest papers.

The most usual definition of "opening angle" is as you have it in the article. It might be easier to just say "Earth would only be in danger if it lies along a line-of-sight within the opening angle of the eventual GRB (that is, the star lies pole-on to Earth to within half the opening angle)."

Even then Earth so far from WR104 as to be at the extreme end of the dangerous range for GRBs (although exactly what this range is depends on still further unknown factors).

You should also mention somewhere that while the pole-on orientation is supported by imaging studies (starting with my work), this interpretation was not backed up by spectroscopy. Studying the radial velocity excursions of certain stellar lines, my colleague Grant Hill at Keck decided that the inclination was more like 30degrees:

Just how to reconcile these conflicting data from two different (but on the surface of it valid) approaches is not yet clear. Or at least, that was the way things stood a couple of years back and I have not looked into it lately.

I also think this statement: "WR 104 is believed to have sufficient spin to create a small possibility of such a hypernova" significantly overstates the case. Really, we don't know. It is very hard to measure rotation velocies for WR stars like these. Statistically, it is hugely unlikely that WR 104 can create a GRB, simply because GRBs are very very rare in metal rich old galaxies like ours. WR104 is also in a binary that has fingerprints of past mass exchange, so this makes it all but impossible to know what might have happened to the stellar spins.

In summary, although I know of no way to categorically rule out the potential for harm from WR104, the odds are extremely long that this is something we need to worry about.

Cheers Peter Tuthill — Preceding unsigned comment added by (talk) 23:42, 20 December 2015 (UTC)

Thanks! Rolf H Nelson (talk) 00:43, 1 May 2016 (UTC)
Yeah thanks! I would however really like to see these "facts" and arguments in a scientific paper. Then we can refer to such a paper. Is it really true that the Wolf-Rayet star has a high metallicity? It should be fairly easy to measure I would say. Other scientists predicts it to go hypernova, not just supernova. What are they basing that on? RhinoMind (talk) 22:32, 25 July 2016 (UTC)
Besides, what you explain is a long list of unknowns. From this we cannot conclude any "unlikely-ness". We can only conclude uncertainty. RhinoMind (talk) 22:39, 25 July 2016 (UTC)
Maybe I should mention that I am also an astrophysicist myself. I personally dislike mentioning title or "rank" in any discussion of this nature. Because it is in total opposition to the nature of scientific thought. We should discuss and argue with content, logic, facts and published papers. And that is no matter "who" we are. RhinoMind (talk) 22:43, 25 July 2016 (UTC)
Actually RhinoMind, this whole text should be argued from WP:NPOV. The current document fails because it is not neutral, to complex, and easily overstates the nature and importance of WR 104. Whist the influence on the Earth for its distance is interesting, it is trivial and needlessly over-speculates the facts. (Gamma 2-Velorum is a much more worrying progenitor to damage life on Earth. Another is Betelgeuse, but its uncertain distance makes this more uncertain.) The text isn't supposed to be a scientific paper but readable to the average Wikipedia reader. Sorry, this article really needs to be severely culled. Arianewiki1 (talk) 15:27, 20 January 2017 (UTC)
I think I understand why you want it culled. But it is important to be aware of this article's history. Previously there were much speculative info about the cataclysmic potential of this WR star. Probably because it has received quite some attention in popular media. That in itself makes it a notable system. We tried to up the quality of information and stick to science as much as we could and I beleive that we have mostly succeeded in that. Generally speaking, I believe that this is the most constructive approach to issues like this. Yes, some culling could be done, it is not a finished nor perfect article. Are the examples you mention possible GRBs? I don't think so from the top of my head? RhinoMind (talk) 03:47, 21 January 2017 (UTC)
The greater astrophysical problem is theory versus observation. General readers can't tell these differences, and when stating things as fact when they are speculative and compete with multiple theories. GRBs are exactly that, as there are many unknowns or uncertainties. There is nothing wrong is saying "astronomers are uncertain" or are conflicted. Expanding all the "what ifs" basically unnecessary, though leaving a brief path of further investigation might be far more useful. (Both these examples are not good GRBs, but there proximity means the fluxes of gamma-rays might be. However the opinions of there possibles vary wildly in the literature.) Arianewiki1 (talk) 06:37, 21 January 2017 (UTC)
Hi. I think most of the clutter in the "doomesday section" came about because we were so lucky that one of the original academic authors (Tuthill) posted some replies and elaborated on the doomesday scenario on this pages TalkPage some time back (before my time around). And editors - understandably - wanted to preserve and incorporate these remarks somehow in the article itself. If you read the original paper, there is also some elaboration on the scenario, but not as much as Tuthill's comments here. Just to your information. As you, I wouldn't mind if the uncertainty aspect was emphasized more, but no matter how it is done, we need to at least provide some information about why WR 104 has been considered a possibly dangerous star, whether it actually is or not. While I am not the biggest fan of the current state of the "doomesday section" as is, I can live with it. RhinoMind (talk) 01:42, 22 January 2017 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:WR 104/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Last edited at 20:32, 24 February 2015 (UTC). Substituted at 10:07, 30 April 2016 (UTC)

Solid scientific refs needed[edit]

Whether or not a GRB from WR 104 will pose a danger to life on Earth is an unresolved matter. Some tabloid refs have been playing alot with potential cataclysmic scenarios and a few journalists have decided that WR 104 is unlikely to pose a danger. This "unlikely-ness" is not backed up by the scientific facts we have about WR 104. Here are the reasons:

  • The Wolf-Rayet star will with 100% certainty go bang. The question is when. And science has even predicted that it is right now. "Right now" in an astrophysical context that is. I haven't seen any science on WR 104, that doesn't predicts it to go hypernova. And hypernovas means long-duration GRBs. We at least know that much about cosmic GRBs. They are not complete enigmas anymore.
  • In estimating the level of subsequent potential danger, the alignment of the rotational axis of the GRB progenitor is vital. Scientists have estimated the rotational axis of the Wolf-Rayet star to be aligned with the general rotational axis of the binary system of WR 104 and hence directed towards Earth. New spectroscopic measurements however, leave room for the stellar axis to be as much as 30-40 degrees off, but I am not aware of any precise measurement. This means that Earth is very likely to be hit by a polar radiation cone of gamma-rays (and subsequent radiation) when WR 104 goes bang. (GRB-radiation cones are about 20 degrees wide mostly)
  • We miss scientific refs on a GRB scenario of WR 104, which takes the distance in to account. Apart from the magnitude of the blast, the distance is for obvious reasons also very important.

As long as there are no scientific model calculations to refer to, we can only say that it is "unclear" if the GRB from WR 104 will pose any danger to life on Earth. RhinoMind (talk) 22:22, 25 July 2016 (UTC)

Remember WP:TRUTH and WP:OR. As long as there are "no scientific model calculations to refer to", we can say nothing. Simply describe what reliable and verifiable sources are saying. The main reference used in the article says a GRB is "highly unlikely". It doesn't even use the word hypernova and you'll have to work very hard to find it in any scientific paper about WR 104. The fact that you need to explain your own arguments for the likelihood of a GRB and the likelihood of it hitting Earth show exactly what shouldn't be going in a Wikipedia article. Lithopsian (talk) 10:03, 26 July 2016 (UTC)
"Nothing" in this context is "unclear" or "unknown". To say it is unlikely is original research that is not backed up by any science. Tabloid journalists is not a credible source in this case. So, as you also point out, we can say "nothing". To conclude that it is "unlikely" would require some serious calculations and more facts and measurements of the nature of the Wolf-Rayet star in WR 104. Something this article clearly lacks.
What is "the main source of this article"? Could you be more specific? I cannot engage in a discussion, if I don't know what source you are referring to.
(personal stuff) I think you should pack away your rudeness and try to act more mature if you want to contribute with anything. I find it idiotic that you choose to bash me because I actually document stuff, while other editors have been making original research and being overly casual in their work. RhinoMind (talk) 15:44, 26 July 2016 (UTC)
I would like to point out that a typical mistake made by journalists (and sometimes mediated by astronomers too) is how chance and probability works. If a scenario has many unknowns or requires a specific string of events, there is a tendency to conclude that the scenario is "unlikely". That is wrong. That is not how probability and chance work. This comes down to basic mathematics. All that can be said and concluded is that "we don't know". Again (as above) this is not an "argument" I made up for the occasion, I am just saying what is already well-known in the fields of mathematics or astrophysics for that matter. Whenever a sceintist omits the scientific language in the mediation of a scientific subject, information is lost and the chance of misunderstandings rises. RhinoMind (talk) 17:13, 27 July 2016 (UTC)
IMO if an event requires a specific string of events, each of which seems improbable, then the scientists are justified in stating that the event is unlikely. That said, if there's a good source saying it is not likely, or specifically that it is unknown whether it is likely or unlikely, then we can add that in. But the current mainstream view among scientists seems to be that the event is unlikely, rather than that the probability cannot be even guessed at. Rolf H Nelson (talk) 03:55, 29 July 2016 (UTC)
Hi. It is an important discussion and of fundamental importance to the understanding of what science really is. As I pointed out it is a very common misunderstanding to conclude an unlikely-ness, when things are really unknown. What you call "improbable" is not improbability in the mathematical sense of this word. It is just to say that only a small number of X objects shows Y behaviour, but we do not know enough about this specific object to tell if belongs to this small number of X objects. It is lack of knowledge. To see why you cannot work with mathematical probabilities like you (and others) do, I can give a general explanation, without using complicated mathematical language. Every event in the world, specifically every prediction of any event in this world, can be broken down into an endless strings of sub-events in an endless variety of ways even, all depending on how you as an observer choose to view and describe it. This mean that the calculation of the probability that this event would take place, would depend on how you as an observer would choose to describe, understand and explain this event. This is meaningless, as it can lead to endless differences in the probability. QED. Extra: Following this argument through you could even reach to the conclusion that the probability that any event would occur is zero. The real world does not work by a "string of events" scenario, that is not how reality works, because reality does not have a meta-script and reality does not have a specific goal to reach. RhinoMind (talk) 16:34, 29 July 2016 (UTC)
Whenever every-day language is mixed with science, problems can arise. This is a commonly occuring example of that. RhinoMind (talk) 16:46, 29 July 2016 (UTC)
Another, slightly different example to explain how misunderstanding can arise, is this: Think of a person who is an albino (or anything rare within a larger group). If you cannot see and doesn't know anything about this person, and you where asked: "Is this person an albino or not?" you would probably say "no", because thinking of the larger group of all humans, the chances that a randomly picked person is albino is slim. If you discuss the issue further, you would probably say that "but there is a chance that this perosn is". If then asked: "Well then, what are the chances that this person is an albino?", you would then have to reply that "the chances are slim and it is highly unlikely". This is all good and solid, but in the real world the person is either an albino or he/she is not. Your probablity and chance talk only applies to your observational model and not to the real world. Even if said person is an albino, you would still argue the way you do, because you simply have lack of knowledge. When we describe the world and events in reality, we are likewise making use of a model-description. This example exposes a common misalignment between reality and the abstract models we make. And it exposes the problems of using probabilties and chance. RhinoMind (talk) 17:37, 29 July 2016 (UTC)
I personally disagree with the criticism of what I regard as conventional mainstream Bayesian probability models, but this is WP:NOTAFORUM. If the scientific community believes something is unlikely, we'll report that it's unlikely. If there's a strong source that believes it likely or strongly believes that its probability can't currently be meaningfully classified by anyone, we can report that too. Rolf H Nelson (talk) 03:59, 1 August 2016 (UTC)
Exactly. If it takes more words than the article itself to join the dots then we shouldn't be saying it. We should simply report what reliable sources say on the subject. With "reliable" in my book not including press releases, definitely not including media articles mangling or hyping those press releases, and just about including "blogs" by published professionals. Lithopsian (talk) 11:05, 1 August 2016 (UTC)
Thats is a silly argument to bring along in this case. It shows that you haven't cared to investigate what the original disagreement was about. My long posts are not an attempt to join any dots, as I am not the one trying to make a synthesis of anything. On the contrary. RhinoMind (talk) 01:48, 3 August 2016 (UTC)
Hi, yeah had the thought about WP:NOTAFORUM myself actually, but felt I at least needed to explain myself. Anyway, many many pages on WP would need a change in this regard if editors had the same level of insight in to how science and probability works, so I am not in tears over this page. I have to add though, that "the scientific community" does not believe it to be "unlikely". They explains that we are lacking in knowledge, which - as I think I explained earlier - could not be extrapolated to say that it is "unlikely". I have however, added missing information to the page, so things have gotten a perspective and I will not press on for this at the moment. RhinoMind (talk) 01:43, 3 August 2016 (UTC)

Some journalists have spoken with mainstream scientists, found out from the scientists that WR 104 is unlikely to pose a danger, and then published magazine or newspaper articles accordingly. These published pop-science articles are suitable for inclusion in Wikipedia per WP:WEIGHT. In addition, blog postings from recognized subject experts are sometimes admissible, per WP:BLOGS. Rolf H Nelson (talk) 03:10, 27 July 2016 (UTC)

Hi. Yes I think we could re-include them in a secion of their own, called "In the press". Scientific sources are of course much more credible in their own right and I am currently working on supplying them. RhinoMind (talk) 03:20, 27 July 2016 (UTC)
Now re-included in a section of its own. RhinoMind (talk) 16:57, 27 July 2016 (UTC)

Nebula, binary system or the Wolf-Rayet star?[edit]

At the moment it is not clear what the scope of this article is. The box is a star-box and only describes the Wolf-Rayet star. For historical reasons WR 104 can mean both the WR star, the binary system or the WR nebula. The text in the article describes the total system, including the nebula. For clarity I suggest that we make a new separate page for the nebula, called the Pinwheel Nebula in the literature, and outfit it with a nebula-box. That is how other nebulae are handled. Then this page can perhaps describe the star system. Preferably with info on when the secondary star was discovered. And hopefully more about the stellar system facts. Radius, more data on the third star, etc.. RhinoMind (talk) 03:18, 27 July 2016 (UTC)

There is no fixed prescription, but clarity should be paramount although WP:NOTABLE obviously also applies. For multiple star systemms, things are fairly clearcut. If the companion is not sufficiently notable in its own right, then it should not get its own article (even if it is notable it doesn't have to get a separate article, redirects are good). In this case, I can't see that an "invisible" B-class main-sequence star in any way needs its own article. The starbox template fully supports multiple stars. The nebula is more difficult. Starboxes have no provision for nebula information. One example is the Homunculus Nebula around Eta Carinae, which has a separate article. It is also a far more notable object than the WR 104 nebula, visible in almost any telescope and with a name going back a long way. I wouldn't create a separate article in this case, the nebula is difficult to discuss separately from the stars that form it and the article is barely longer than a stub as it is. Lithopsian (talk) 11:00, 1 August 2016 (UTC)
"The nebula is more difficult" That was my main point of concern. I am not knowledgeable enough about the nebula to say if it is notable or not. I guess we leave it as is then? I am glad to learn that we can add information about the other two stars to the star-box, that solves part of the problem. RhinoMind (talk) 02:43, 3 August 2016 (UTC)
This following statement said above is quite wrong: "For historical reasons WR 104 can mean both the WR star, the binary system or the WR nebula." WR means Wolf-Rayet for the primary only, and the WR 104 comes from the 6th Catalogue of Wolf-Rayet's. The components follow those of single or double stars, in this case (as preferences by the IAU standards, CSI-23-17590 A, B or C, while the nebula is Ve 2-45. Collectively, it is more importantly known by the WR 104 label, so it is best to keep everything together here. Arianewiki1 (talk) 15:05, 20 January 2017 (UTC)
No it is not wrong. If you read up on the subject you would come to know that it was not until recently that it was discovered that WR 104 was a star and a binary system even. It used to be described and understood as a so-called "pinwheel nebula", now an obsol≈ete term. For this reason, "WR 104" is sometimes referring to the whole "nebula" (ie. the whole binary system) when mentioned in academic papers, even recent ones. A good start is to read the article on Wolf-Rayet nebulaes first.
While this doesn't change the conclusion here, it is valuable knowledge. RhinoMind (talk) 02:32, 21 January 2017 (UTC)
Eh? "If you read up on the subject you would come to know that it was not until recently that it was discovered that WR 104 was a star and a binary system even." Wow. Nice condescending attitude there, especially when you don't know me nor have any inkling of my depth of knowledge. (Relying on assumption rather than any evidence discloses more about you than me.)
As for saying "For this reason, "WR 104" is sometimes referring to the whole "nebula" (ie. the whole binary system) when mentioned in academic papers, even recent ones."
Um... Does it now? Designations usual depends on the background of the investigator. Funny. I look in the 6th Galactic WR Catalogue (1981) - which I own actually - and this isn't true as it states what I wrote above. The stars were designated in the Catalogue of Stellar identifier (CSI) in 1973, with the third component designated in 1981. WR 104 was first classified as such in this 1981 source. The nebula was discovered first by Velghe in 1956, though the WC8 classification was discovered in 1962. Most of the nebula observations appear in the IR, and most of these sources use IR designation the WR 104. Its binary nature was first found in 1974, and given as a variable star in 2001 (in the GCVS 76th Name list.)
Here the real evidence says your conclusion here is an un-referenced assumption, probably designed just to put me off the scent. Ergo, it is your statements that are wrong. (Henceforth, every thing you say on WR 104 cannot be trusted, because if you state falsehoods here, it augurs you do for everything you say. Yet you have the audacity to expect me to play nice. BS. You should be ashamed of yourself.) Arianewiki1 (talk) 07:49, 21 January 2017 (UTC)
I can't relate to what you talk about here. Just read the refs and sources in the article, that's all. It is neither condescending nor too much to ask that editors read refs and sources in an article. RhinoMind (talk) 02:01, 22 January 2017 (UTC)

Quite Messy Article[edit]

This article still needs a lot of work, as it if full of speculation and poorly cited material, which seems to be just from one solitary source. Much of the material is repeated several times throughout the document, making the whole text near impossible to read. Some is contradictory too.

The threat to Earth is interesting, but it is both overstated and discussed out of proportion to the actual reality. It read much like personal research and is not written from a necessary WP:NPOV. 70% could easily be culled, IMO.

Worst, the text reads in terms of absolutes when much of the story is conjecture. A supernova is the final event (absolute), but as the star has not gone supernova, the scientific truth is really an expectation (speculative.) I.e. It is likely or predicted to go supernova, but this is not written in stone. (It is also possible for example, that an accretion disk or super-wind could remove much of the outer radiative region into space, downgrading the mass so that it does go supernova or as a core-collapse-SN. The binary companion could change that too.)

Also the editor(s) here should stop the repeated use of 'supernova explosion'. (I have removed nine six of them!) Another is the repeated use of "destructive", which the term supernova already implies. Also these same editor(s) have used the same wrong terminology across multiple Wiki pages. By definition, a supernova is already a 'destructive exploding star', so why repeat it again (and again)? It is a simply a supernova or SN Type (whatever). Arianewiki1 (talk) 14:44, 20 January 2017 (UTC)

Hi. I would like to respond to your comments and will do so by numbering your paragraphs:
1. It is not spectacular news that articles on Wikipedia are in need of further work. You should be happy that there is an article in the first place. You do however, point to some areas were progress could be made and I especially agree on the repetitions that you mention (although "impossible to read" is a ridiculous overstatement, unless you are not able to read anything in the first place). The solitary source claim is ungrounded.
2. The threat to Earth topic is indeed interesting, in particular because it is the only GRB candidate that could potentially damage the ecosystems on the Earth. Correct me if there are others, please. The topic is more than interesting, it is also notable, because it has experienced intense attention in popular media. This is probably the most important reason for it to be elaborated on in the article. If you have better suggestion for a rephrasing, then just go ahead. Just be sure to keep every bit of information; a task that often turns out to be challenging for editors. If you want to cull anything, just be aware that you do it right and that the this topic has a history of editorial conflict - to put it in diplomatic terms.
3. If you have a source for your speculation about alternative outcomes, I think many people would appreciate that you put it in the article. If you are right, it would be great to read a bit about it.
4. Good copy-editing point here! But... the word "destructive" is sometimes referring to the ecosystems on Earth and not the self-imposed destruction of the star. In these cases, "destructive" is necessary to keep of course. It should be evident from the context what "destructive" is referring to.
To finish off, I would like to salute the editors of this article. The article is much much better than it was a year ago. Great work! RhinoMind (talk) 03:03, 21 January 2017 (UTC)
@Arianewiki1:Having gone through your edits so far, I can see that you have not added anything of value to the article, but have actually messed up a few things and made it worse, in particular the lede section. Every topic is adressed in the comments above. Will you revert yourself? RhinoMind (talk) 03:22, 21 January 2017 (UTC)
Nice condescending slight, but I will not bite. I will not be reverting anything unless you can defend actual errors or mistakes via this Talkpage. (That is how editing works here.) You obviously make the same mistake of many editors, by attacking the person instead of the debating text in the document. Arianewiki1 (talk) 08:04, 21 January 2017 (UTC)
Ok, I'll try. I would think the reasons were obvious, but maybe they are not. There are several issues. First, as already concluded in a discussion section above WR 104 is not just referring to the Wolf-Rayet star. The WR-abbreviation does not stem from the Wolf-Rayet star, but was introduced because WR 104 was categorized as a Wolf-Rayet nebula originally. And the pinwheel nebula categorization is archaic and obsolete in astrophysics. WR 104 is sometimes referred to as THE Pinwheel Nebula for historic reasons only. (please read the references and sources in the article to check facts here. It shouldn't be necessary to state this at all. Sorry.) Then there is the issues about cn-tags. Please don't put them in lede sections. Why not? Because lede sections only summarizes main points from the body. Usually. So please insert tags in the body if possible. Forgive me if I have overlooked some issues here, but I think these were the main concerns about your edits. RhinoMind (talk) 01:54, 22 January 2017 (UTC)
₨Nope. "WR 104 was categorized as a Wolf-Rayet nebula originally." WR 104 was catergorised by its spectra, the nebula was known beforehand. WR Nebulae were not known until the 1980s. Arianewiki1 (talk) 10:51, 22 January 2017 (UTC)
Put that in the Wolf–Rayet nebula article, with proper references. Please. RhinoMind (talk) 04:12, 23 January 2017 (UTC)
If your info here somehow affects this article and the history of WR 104 observation and catgorization, then please go ahead too. Just use proper references (and it is still a good idea to read those that are already up too). RhinoMind (talk) 04:15, 23 January 2017 (UTC)

WR designations[edit]

What happened? When did a WR designation change to be just a single component of a binary or multiple system? Without any references? The Galactic Wolf Rayet Catalogue which assigns WR designations certainly doesn't say that. Lithopsian (talk) 14:28, 23 January 2017 (UTC)

"What happened? When did a WR designation change to be just a single component of a binary or multiple system?" I didn't, the designation has always been this way. Clearly impossible to answer or reference, and plainly logical and sensible.
As for. "The Galactic Wolf Rayet Catalogue which assigns WR designations certainly doesn't say that." Well, what does the "Galactic Wolf-Rayet Catalogue" actually say? (Actual quote please.)
The first use of these designations come from the 6th Catalogue (1982), where 158 stars are listed. Only 18 are in binary systems, and these are sometimes defined WR binaries. The WR binaries are of special interest, because Massey in the early-1980s theorised that they all evolved from O-type stars, became Of stars then WR stars. (Evolution by others found the originally O+O type stars, become a WR+0 then Compact star+WR.)
Your interpretation seems to think the 6th Catalogue is a list of WR binaries, but there is NO statement in the 6th Catalogue nor any inference. (I have this Catalogue in my hand now, and no where can I find anything like your assumption.)
The 7th WR Cat says: "The VIIth Catalogue of Galactic Population I Wolf-Rayet (WR) Stars provides improved coordinates, spectral types, and bv photometry of known WR stars and adds 71 new stars compared to the VIth Catalog. This census of galactic WR stars has reached 227 stars (226 entries in this catalog), comprising 127 WN stars, 87 WC stars, 10 WN/WC stars, and 3 WO stars."[1]
This shows that the Catalogue comprises only Pop I WR stars, but binarity among this class of stars isn't considered. In the 7th Cat, there are designations that uses an additional letter. I.e WR 102l or WR 48a, but these are not components to the WR stars but newly discovered ones since the 6th Cat (1982)
Plainly the definition of a WR star is "A member of a class of stars, exceptionally hot stars with surface temperatures of 20,000-50,000K. Their spectra show strong broad-band emission lines : in WC stars, carbon dominates whereas in WN stars the dominant emission lines are of nitrogen." (Dictionary of Astronomy Mitton, 1991)
A Wolf-Rayet star is defined by its spectra, a catalogue of Wolf-Rayet must be simply based on that definition.
Examples: "So what is causing this spiral structure around WR 104? The star has a binary O-type star partner, so as WD 104 sheds its mass, the stellar winds spiral outward."[2] This infers WR 104 is the star in question not the system.
Forbes reports (saying the same thing): "Although WR 104, a Wolf-Rayet star some 8000 light years distant, has thus far remained largely quiescent, it is ripe to undergo a core-collapse supernova of the sort that could generate a seconds-long burst of gamma-rays that, in turn, might potentially wipe out a quarter of earth’s protective atmospheric ozone." [3]
The only sources I could find to support your notion is Peter Tuthill (which seems to be the earlier research for the Wiki article. I,e, "OK - firstly remember that WR 104 is a binary star system with two very massive stars." [4] It is probably just clumsy writing. Arianewiki1 (talk) 03:53, 24 January 2017 (UTC)
Just a short side notice: If a Wolf-Rayet OBJECT is characterised by its spectra alone (which I suspect is/was the case), then the WR designation must automatically comprise the entire WR 104 system. At least originally. Also several recent sources refer to the entire nebula as WR 104 (here is one: The Prototype Colliding-Wind Pinwheel WR 104) Generally: I prefer that editors read refs and sources in articles before engageing with them and we should use proper scholarly sources if we are to nitpick definitions as done above. RhinoMind (talk) 04:35, 24 January 2017 (UTC)
So are you're inferring that O-type stars are now WR-stars? Spectra are combined in such stars I.e. WC9d+B0.5V (+VB), but only one star is a Wolf-Rayet, whose components are resolved as a spectroscopic binary. The WR component is the generator of the spiral. Again, the spiral nebula is catalogued as Ve2-45. The WR is the one to first go supernova. Read the whole text of the 6th and 7th. Nothing like this is said or inferred. Arianewiki1 (talk) 09:35, 24 January 2017 (UTC)

Not going to hit Earth - pretty much certain now[edit]

The lede is misleading when it says

Some articles decide to reject the catastrophic scenario, while others leave it as an open question.

The articles cited that say it will hit Earth are dated around 2008, or they are based on these older articles. The ones that say it will miss are from 2009 onwards. So the variation in what the articles say is a result of a progression in understanding, not a variation in opinion about what is known. What happened is that spectroscopic observations now strongly suggest that it is tilted at an angle of 30°-40° and so any gamma ray burst can't hit us. See [5] and also [6]

There are other things that make gamma ray bursts unlikely too. They occur preferentially in metal poor dwarf galaxies. Ours is a larger metal rich galaxy. Our galaxy is about as large a galaxy as one can be and still have gamma ray bursts, but also metal rich and it is so far less likely to have them than most galaxies. For details see this paper ( which says "We find that only galaxies with present stellar masses below < 10^10 M☉and low metallicity reproduce the observed GRB rate."

See also this list of Gamma Ray Burst Host Galaxies ( Our galaxy has about 100 billion times the mass of the sun, so would have a figure of 11 in the log (M*/M?) column - at the time of the article they said they were all in dwarf galaxies - and there is currently only one example of a nearby GRB in such a large galaxy, GRB 080207 (

For all these reasons they seem unlikely to occur often in the Milky Way.

For details see Astrobiological Effects of Gamma-Ray Bursts in the Milky Way Galaxy (

Conclusion of that study was

The results in this work, and others found in the literature imply that GRBs may be uncommon in the Milky Way and may not pose a significant danger to the propensity of planets to host life in the Galaxy.

Robert Walker (talk) 17:52, 12 February 2018 (UTC)

Decided to "be bold" and just added an extra sentence: "However spectroscopic observations now strongly suggest that it is tilted at an angle of 30°-40° and so any gamma ray burst can't hit us." cited to the Universe Today source. Robert Walker (talk) 18:01, 12 February 2018 (UTC)