Betelgeuse

[[File:Betelgeuse_Plume_eso0927d.jpg|thumb|165px|Artist's illustration of Betelgeuse. Note its size compared with the Solar System, and its distorted look]]
{{Astronomy}}
{{hatnote|If you're looking for {{wpl|Beetlejuice||,}} Tim Burton's 1988 film starring Michael Keaton, you're not going to find a page about it on this wiki.}}
'''Betelgeuse''' is a bright [[star]] in the winter<ref group=note>Summer for those who live in the Southern hemisphere</ref> constellation of Orion. It's also its second brightest star after {{wpl|Rigel}} &mdash; despite having been classified as the brightest one, at least in visible light.

[[Fun:The Hitchhiker's Guide to the Galaxy|Ford Prefect]] comes from a small planet near it.

==Physical properties==
[[File:Betelgeuse pulsating UV (HST).jpg|thumb|left|165px|Four [[UV]] images of Betelgeuse showing irregular pulsations]]
Betelgeuse is a red supergiant star, an evolved high-mass star that has exhausted all the [[hydrogen]] at its core (see also [[Star#Beyond main sequence|stellar evolution]]) and is fusing there heavier elements before its final death as a luminous, bright-as-a-galaxy, supernova, and not only is one of the brightest stars of the sky, but also a very luminous and large one.

This star lies at a distance of around 640 light-years, being up to 150,000 times more luminous than our [[Sun]]<ref name=beetlejuice>[http://adsabs.harvard.edu/abs/2009AJ....137.3558S Red Supergiants as Potential Type IIn Supernova Progenitors: Spatially Resolved 4.6 μm CO Emission Around VY CMa and Betelgeuse]</ref> and has an ill-defined diameter (due to the fact that its mean density is ''very'' low, virtually a vacuum by Earth's standard as well as that it has both a very extended atmosphere and it's "boiling", covered by large convective cells &mdash; see images) that ranges between roughly 900<ref name="beetlejuiceboom">[http://adsabs.harvard.edu/abs/2016ApJ...819....7D Evolutionary Tracks for Betelgeuse]</ref> and 1,200 times the one of our daystar.<ref name="beetlejuice" /> This had led some astronomers to think Betelgeuse may be contracting,<ref>[http://adsabs.harvard.edu/abs/2009ApJ...697L.127T A Systematic Change with Time in the Size of Betelgeuse]</ref> but that contraction could not be real and simply be caused by said large convection-induced protrusions as the star rotates. 

Like many other red supergiant stars, Betelgeuse's brightness changes irregularly. However, as of late 2019-early 2020, it had abnormally faded, losing 1 magnitude (ie, becoming 2.5 times fainter), being no longer among the brightest stars in the sky,<ref>[http://www.astronomerstelegram.org/?read=13410 The Continued Unprecedented Fading of Betelgeuse]</ref> what fueled speculations of its supernova time coming soon despite astronomers thinking it still has a lot of years to shine (see further down). However, from February 2020 onwards, its brightness has stabilized and it has begun to slowly recuperate the lost one, astronomers thinking the cause of said fainting being both those brightness variations as well as large amounts of circumstellar dust produced by the star eclipsing it,<ref>[https://arxiv.org/abs/2002.10463 Betelgeuse Just Isn't That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse]</ref> until Betelgeuse became again as bright as in the past some months later<ref group=note>Since then, {{wpl|RW Cephei|other}} extremely large stars have been observed to suffer similar dimmings</ref>.

A considerable increase of brightness of Betelgeuse in 2023 had led some astronomers to think supernova time is coming soon, as the star would be on {{wpl|Carbon burning process|its last legs|.}} However, the same astronomers who have proposed that also think it could still be in an {{wpl|Triple-alpha process|earlier and much longer lasting nuclear burning phase,}} thus being destined to last much more time<ref>[https://arxiv.org/abs/2306.00287 The evolutionary stage of Betelgeuse inferred from its pulsation periods]</ref> as also noted in the next section.

A possible much fainter companion to Betelgeuse has been described in 2025. If such star (often named "Betelbuddy" or "Siwarha" ("her bracelet" in Arabic)) exists it orbits very close to the red supergiant and is likely young, [[Sun]]-like, still in formation having not initiated nuclear burning yet, and being destined to merge with Betelgeuse within some thousands of years.<ref>[https://arxiv.org/abs/2507.15749 The Probable Direct-Imaging Detection of the Stellar Companion to Betelgeuse]</ref><ref>[https://iopscience.iop.org/article/10.3847/1538-4357/adff83 Betelgeuse’s Buddy: X-Ray Constraints on the Nature of α Ori B</ref>.

==Woo==
The fact that the end is nigh for Betelgeuse has attracted a considerable amount of woo around it and the effects of its death on Earth. [[YouTube]] has quite a few videos about that, including that it would have blown up in [[2012_Apocalypse|2012]],<ref group=note>[https://www.youtube.com/watch?v=Ax77yzAKvRY Yeah, right]. Of course it's not justified why it's shining as usual years later{{nofact}}</ref> being as bright as a second Sun,<ref>[https://www.youtube.com/watch?v=79x3RcmkXCY Supergiant FAIL]</ref> as well as other warnings of that going to explode in any moment. Other pages are no less full of [[bullshit]], thinking Orion is far smaller than it actually is, and that Betelgeuse can be eclipsed by the Sun (it doesn't).<ref>[https://starviewerteam.com/2011/01/19/betelgeuse-ya-exploto-hace-590-anos-y-vamos-a-presenciar-un-segundo-sol-una-supernova-iluminara-el-cielo/ You fail Astronomy forever (in Spanish)]. Go [https://starviewer.files.wordpress.com/2009/08/aaaaaaaaa1.jpg?w=490&h=480 here] to save you time.</ref>

However, recent (2016) calculations suggest Betelgeuse still has ~100,000 years to live before going supernova,<ref name="beetlejuiceboom" /> with also the possibility of it exploding not as a red supergiant but as a smaller and hotter star instead.<ref>[http://adsabs.harvard.edu/abs/2013A&A...558A.131G Fundamental properties of core-collapse supernova and GRB progenitors: predicting the look of massive stars before death]</ref>

The Betelgeuse supernova is expected that will have a brightness comparable to that of the full [[Moon]], even outshining it and giving for a couple of months a spectacular light show. However, it will be 
mostly
 harmless and it's expected that neither the neutrinos, the UV/X-Ray/Gamma radiations, or its ejecta will affect [[Earth]] in severe ways from that distance, no matter what woo-meisters may say about ''much'' nastier effects — except perhaps messing with nocturnal animals that would confound the supernova with the Moon. It's also expected that it will leave behind a {{wpl|neutron star}} and not a [[black hole]], a gamma-ray burst being also highly unlikely.<ref name="beetlejuiceboom" />

==External links==
*Betelgeuse awaiting its fiery demise at {{wpl|Betelgeuse|the other wiki|.}}

==Notes==
{{reflist|group=note}}

==References==
{{reflist|2|80%}}

[[Category:Astronomy]]

Categories: Astronomy