Talk:Betelgeuse

arXiv:2408.09089, not yet accepted for publication but something to keep an eye on. SevenSpheres (talk) 16:57, 20 August 2024 (UTC)

Nice. 21 Andromedae (talk) 17:00, 20 August 2024 (UTC)

And now a second preprint supporting a companion to Betelgeuse. SevenSpheres (talk) 02:24, 18 September 2024 (UTC)

@SevenSpheres and 21.Andromedae: And here's direct imaging of the companion from Gemini Observatory, announced today: Hidden neighbor: Astronomers confirm long-suspected companion star near Betelgeuse. The paper: Probable Direct Imaging Discovery of the Stellar Companion to Betelgeuse, The Astrophysical Journal Letters (2025) (link: https://dx.doi.org/10.3847/2041-8213/adeaaf -- that link doesn't seem to work at the moment, but should soon) Renerpho (talk) 17:51, 21 July 2025 (UTC)

Nice. 21 Andromedae (talk) 18:09, 21 July 2025 (UTC)

Here's the NOIRLab press release, with a bit more info -- including links to the two 2024 papers (1, 2) and acknowledgement that they were used to predict the companion's location. Renerpho (talk) 19:19, 21 July 2025 (UTC)

And here's the actual paper, submitted to arxiv on 21 July (to be published on 24 July): https://arxiv.org/abs/2507.15749 I think the fact that this is only a 1.5-sigma detection should be mentioned somewhere. Renerpho (talk) 02:34, 22 July 2025 (UTC)

We need to be careful with whatever we add to the article, about the properties of the companion, because the press releases (including that from NOIRLab themselves) contradict the paper in several points. For instance, where the NOIRLab press release says that the companion has an estimated mass of around 1.5 times that of the Sun, and it appears to be an A- or B-type pre-main-sequence star — a hot, young, blue-white star that has not yet initiated hydrogen burning in its core, the paper states: Assuming the companion is coeval with Betelgeuse with an age of 10 Myr, the companion has a mass of ∼ 1.6M⊙ and is likely a young, pre-main-sequence F-dwarf (that is, a relatively cold, yellow/white star). And the image from the press release does not appear in the paper. In fact, the images in the paper indicate the detection is of much lower significance, and they say so themselves ("1.5-sigma"). Also, the results presented here are not definitive, as the detection is at the limit of the instrument capabilities is something that should not be overlooked. We must not state this as a definitive discovery, and I don't think we should claim that Betelgeuse is definitely a binary at this time. Renerpho (talk) 02:49, 22 July 2025 (UTC)

Yeah, it is a shame that the media is overly-sensacionalist, saying that a less than 2 sigma detection is an ultimate detection and that the existence of Beletelgeuse B is now a fact carved in stone. That's why i do not trust anything from press relases and media without checking the paper first. 21 Andromedae (talk) 21:01, 22 July 2025 (UTC)

From the Spelling and pronunciation sub-section in the Ethnological Attributes:

"/ˌbɛtəlˈɡɜːrz/ BET-əl-GURZ – Martha Evans Martin, The Friendly Stars[200]

"The -urz pronunciations are attempts to render the French eu sound; they only work in r-dropping accents."

What Martin actually wrote was:

"Bet-el-gerz ́ "

Martin gave no key to the pronunciation, so the interpretations given in both IPA and English Respelling appear to be individual research at best, and possibly pure speculation. Also, the pronunciation attributed to Martin is simply not what Martin wrote. The statement about r-dropping accents may very well be true, but it is not supported by any citation. So I intend to delete the pronunciation, because it's not found in the cited reference, and the comment because it's uncited and has no relevance once the pronunciation is deleted.

Any objections? After about a week, if there are no valid objections, or actual citations in support of the material, I will delete it. 172.56.194.177 (talk) 22:57, 26 January 2025 (UTC)

I also think it should be removed if a source that properly verifies cannot be found. Remsense ‥ 论 17:19, 31 January 2025 (UTC)

Betelgeuse B is said to be tidally decelerated and is expected to collide into the giant star in 10 000 years, forming a red nova. I wonder if Betelgeuse B would scatter the other layers of the primary, leaving behind a bare core akin to cataclysmic variables. Pancakes321 (talk) 06:33, 22 July 2025 (UTC)

Someone with expert knowledge and a current source should fix the text —— Sbalfour (talk) 19:26, 17 November 2025 (UTC)

@Sbalfour: Where is the confirmation? Last I have seen is the paper by Howell and collaborators from July 2025, and IAU's naming of the possible companion in September 2025. The result from the paper is unconfirmed, as far as I am aware, but if that has changed in recent weeks then I'm all ear! Renerpho (talk) 23:25, 17 November 2025 (UTC)

@Renerpho: O’Grady, Anna J. G.; O’Connor, Brendan; Goldberg, Jared A.; Joyce, Meridith; Molnár, László; Johnson, Christian I.; Hare, Jeremy; Breivik, Katelyn; Drout, Maria R.; Moe, Maxwell; Calamida, Annalisa (10 October 2025). "Betelgeuse's Buddy: X-Ray Constraints on the Nature of α Ori B". The Astrophysical Journal. 992 (1): 107. doi:10.3847/1538-4357/adff83.{{cite journal}}: CS1 maint: unflagged free DOI (link) Richard-of-Earth (talk) 07:06, 21 November 2025 (UTC)

@Richard-of-Earth: This is a non-detection, right? Renerpho (talk) 11:38, 21 November 2025 (UTC)

@Renerpho They detected it and concluded it was likely a Young stellar object (YSO). See the last line of the abstract. I am not an expert nor even an amateur, so I do not care to edit the article. I just asked Google for the latest study on this star. Richard-of-Earth (talk) 17:58, 21 November 2025 (UTC)

@Richard-of-Earth: From the abstract: "we do not detect an X-ray source at the position of Betelgeuse ... we can place upper bounds within this range for most absorbing columns. Based on these considerations, we conclude that the companion to Betelgeuse is likely a low-mass YSO." That's a non-detection, which leads them to conclude that the companion, if it exists, must be a YSO (anything else would have been detected). I've added that to the article earlier today. Renerpho (talk) 18:03, 21 November 2025 (UTC)

I have since reverted my own addition though, after I noticed that this article was already in the article, in the sentence starting "In May 2025" (see its original publication here). Renerpho (talk) 18:10, 21 November 2025 (UTC)

My bad, I should have checked the article. I also did not realize the YSO companion did not qualify as part of a binary system. Why not? Richard-of-Earth (talk) 03:58, 22 November 2025 (UTC)

@Richard-of-Earth: That's a misunderstanding. The YSO would be the companion that makes this a binary system. The problem is, it's not certain yet that the companion actually exists. The direct imaging detected it at a low significance, and independent confirmation has not yet been possible. If the companion was something else, rather than a YSO, it may have been possible to detect it in X-ray. But YSOs don't emit a lot of X-rays... So, the negative detection in X-rays could mean one of two things: Either the companion is a YSO, or it does not exist. Renerpho (talk) 07:06, 22 November 2025 (UTC)

The article now (again) presents the companion as confirmed, based on a NASA press release which says as much. Yet the new paper still uses less certain wording: The occurrence and variation of this plasma appear consistent with the presence of a trailing and expanding wake caused by a companion star orbiting within the atmosphere of Betelgeuse; If the postulated and probably-detected companion to Betelgeuse is confirmed...

Siwarha is certainly a strong candidate with multiple lines of evidence (and an IAU name), but should we present it as confirmed? In any case the new evidence should be discussed in the "Companion star" section, not just in the lead. SevenSpheres (talk) 01:47, 6 January 2026 (UTC)

Go with the paper rather than the press release. Renerpho (talk) 01:52, 6 January 2026 (UTC)

Agreed. The same situation happened with that 'direct imaging' discovery, on which the press releases claimed the companion to be a fact carved in stone, but in reality was just an 1.5-sigma discovery. We shouldn't present the companion as confirmed when all the papers only point to evidences and none claim the companion as a fact. 21 Andromedae (talk) 16:10, 6 January 2026 (UTC)

This paper does not pick a radius but instead describes the radius changing over time during the dimming event. It seems the value of 640 R_☉ was just slapped into the starbox without an understanding of the context behind said value. Specifically, 640 R_☉ was the radius of the star before the dimming event if you look at figure A.1 and A.2, the radius does not return to the same size as before. Faren29 (talk) 17:56, 28 January 2026 (UTC)

The last points of both figues (after the dimming and subsequent increase in radius) are located at roughly 650 R_☉, so the radius return to the original state. 21 Andromedae (talk) 11:23, 29 January 2026 (UTC)