When are you going to blog about the news that Betelgeuse is shrinking and might be getting ready to go supernova? (Might already have and the light hasn’t reached us yet…) Or did I miss a blog post?

Rich

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Update 2008: A new parallax derived from optical and radio observations now place Betelgeuse at a much greater distance of 640 light years, which gives a luminosity of 135,000 times that of the Sun and a radius of 4.4 AU (950 times solar). The optical angular diameter yields a closely agreeable 4.6 AU (996 times solar). The star is 87 percent the size of Jupiter’s orbit. Infrared observations at a wavelength 20 times that of visual light show Betelgeuse to be even bigger, 5.3 AU (just bigger than Jupiter’s orbit), the result of a diffuse surface and circumstellar matter. From the luminosity and temperature, Betelgeuse carries a mass of 20 Suns. With an age of 8.5 million years, it is a prime candidate to explode as a supernova. The star’s motion shows it to be a runaway member of the Orion OB1 association, particularly the subgroup that involves the stars up and to the right of the Belt.
Written by Jim Kaler 11/13/1998; updated 5/20/05; last updated 8/01/08.

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I emailed the BA with this news as soon as I saw it … seems he missed it.

“IVAN, that’s interesting, and new enough I hadn’t heard it. The HIPPARCOS distance was 140 pc, which is what I’ve been using for years.”

You didn’t get my email then which I sent months ago which was updating you on the new distance for Betelgeuse and its implications? (Ie. star being larger than at the closer distance)

Kaler’s stars website has updated the Betelgeuse figures as well.

Its meant to be non-italicised normal font after I finish quoting Imrryr Sorry.

If Betegeuse were very close to us, like [choose your star here] Centauri, what would it look like to us in the night sky? Moon-like? Seen in the day? what? what?

& Chris A responded :

“At the distance of Proxima Cen (1.30 pc), Betelgeuse (at 4.6 AU optical diameter) would still only span an angular diameter of 3.5 arcsec, about 17 times too small to be resolved with the unaided eye into a disk. However, a decent backyard telescope could see its disk quite nicely. Its magnitude would be about -10.4, which would make it about 7.5x fainter than a full Moon (at mag. -12.6).”

Won’t dispute that but rather aim to complement it by saying it would be very bright but still star-like object – probably with a strong red or ornage tinge and much much brighter than Venus or even a first crescent moon! Venus the “Evening” & the “Morning Star” at its brightest is minus four point four. Betelgeux at minus ten would be many times brighter but still a visual point source which I’d expect to scintillate or twinkle strongly esp.,when low in the sky and be easily visible anytime its up day or night.

It would be well and truly bright enough to cast shadows – even Venus can do that at its most luminous. Such a close Betelgeux would be a remarkable sight but also quite a source of light pollution …

Imagine the stories we’d make up about it & the scientific impact it’ds have.

We’d just want it to be a bit further away (like say 100 plus ly) when it goes supernova!

Imrryr said on November 20th, 2008 at 8:15 am :

“That picture and what it represents is quite awesome. Someone tell the two Voyager spacecraft to hurry up and encounter our star’s bow shock already!Here are distances to some of the main stars in Orion: Betelgeuse 640 light years, Bellatrix 243 lys, Alnitak 826 lys, Alnilam 1360 lys, Mintaka 919 lys, Saiph 724 lys, Rigel 775 lys. I’m sure that they will keep revising these for some time to come, but Alnilam (which is the center star in Orion’s Belt) is apparently the badass of the Orion constellation… at least when it comes to luminosity, that star is 112,000 times as luminous as our sun!”

The amazing brightness and range of stellar luminosities never fails to amaze me – I’ll admit to finding it hard to imagine something even twice as bright as our Sun let alone so many thousands or even millions of times brighter still! Eta Carinae being at nearly 5 million x the solar brightness takes my breath away.

Awe-inspiring beautiful image here.

Thanks for posting it & congrats to the team involved. :-)

Reminds me a bit of the UV image of Mira showing its comet-like (in appearance anyway) tail.

Stars are fantastic in UV aren’t they? Oh & they’re not too bad in visual light either!

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Trivial fact of the day : The brightest sky in Ultra-Violet wavelengths is Adhara or Epsilon Canis Majoris, a B2 II blue bright giant star located some 425 lightyears away. (James Kaler, ‘The Hundred Greatest stars’, Copernicus Books, 2002.) If bees do any star-gazing then Adhara would bee the brightest star they’d see!