Astrogator's Logs

New Words, New Worlds
Artist, Heather Oliver             

Distant Celestial Fires

In line with end-of-the-world prophecies linked to Maya calendars, there’s sudden noise on the Internet that Betelgeuse (the bright red star that marks Orion’s left shoulder) will become a supernova in 2012. The segue is that this will first give us Tattooine-like sunsets, then singe earth and all upon it.

Betelgeuse is a gas-shrouded red supergiant of about 20 solar masses whose circumference would extend to Jupiter and whose hydrogen fuel has run out. This does mean that its days are numbered and its end will be spectacular: when it explodes, it will be visible in broad daylight and will cast shadows as strong as those of the full moon. However, it’s easy to find out that Betelgeuse is about 600 light years away. So it’s not close enough to harm us (the radius for harm is 25 ly or less).  Furthermore, if the explosion becomes visible to us in 2012, the event actually happened sometime around 1400 CE. A more in-depth search also reveals that the star’s axis does not point in the direction of Earth, precluding a potentially lethal directed gamma ray burst.

Betelgeuse is a runaway: it started life as a hot blue star in the prolific stellar nursery around Orion’s belt. This region, which includes the famous nebula that forms the middle “star” of Orion’s sword, is still giving birth to new stars. So after Betelgeuse has dwindled to a neutron cinder, it may have a successor. But its death will change the shape of perhaps the best-known constellation – a reminder that in our universe everything is born and will die.

Adrienne Rich wrote her elegiac poem Orion before many details about Betelgeuse became known. Yet she knew more and said it far better than the apocalypse pornographers of the Internets:

Far back when I went zig-zagging
through tamarack pastures
you were my genius, you
my cast-iron Viking, my helmed
lion-heart king in prison.
Years later now you’re young

my fierce half-brother, staring
down from that simplified west
your breast open, your belt dragged down
by an oldfashioned thing, a sword
the last bravado you won’t give over
though it weighs you down as you stride

and the stars in it are dim
and maybe have stopped burning.
But you burn, and I know it;
as I throw back my head to take you in
an old transfusion happens again:
divine astronomy is nothing to it.
Pity is not your forte.
Calmly you ache up there
pinned aloft in your crow’s nest,
my speechless pirate!
You take it all for granted
and when I look you back

it’s with a starlike eye
shooting its cold and egotistical spear
where it can do least damage.
Breathe deep! No hurt, no pardon
out here in the cold with you
you with your back to the wall.

Images: Top, data-congruent rendering of Betelgeuse (ESO, L. Calçada); Bottom, Orion (Hubble ESA, Akira Fujii)

13 Responses to “Distant Celestial Fires”

  1. ZarPaulus says:

    Betelgeuse? Wasn’t that Ford Prefect’s homeworld?

  2. Athena says:

    Who’s he?

  3. Asakiyume says:

    Ever since I found out, in the dim reaches of childhood, that Betelgeuse would one day (or did, one day in the distant past) supernova, I’ve hoped that it would become visible sometime during my lifetime. What a thing to see!

    Pity is not your forte.
    Calmly you ache up there

    Love those lines.

  4. Asakiyume says:

    Also: Ford Prefect was a character from Douglas Adams’s The Hitchhiker’s Guide to the Galaxy and its sequels.

  5. Athena says:

    Thank you — I never read the Hitchhiker series.

    Yes, a supernova is an event of beauty and terror. I read a haunting story once, of a human research expedition reaching a planet whose civilization was extinguished by a nova explosion. The linguist ends up giving her/his life to decipher their script, so that they are not totally forgotten. I can’t recall the author and title right now, but the story has stayed with me.

  6. andy says:

    I’ve always found Orion to be an aesthetically-pleasing constellation, the star patterns somehow feel nicely balanced. Betelgeuse going supernova would be a fascinating event, but it would somewhat “ruin” the constellation.

  7. Caliban says:

    Beautiful stuff, especially the Rich poem.

    Not that it matters, but I think the distance for a biological catastrophe for a supernova is significantly larger than 25 l.y.. I’m sure there are different estimates, but the one I found in the literature was about 40 pc, or about 150 l.y., so we’re still safe.

  8. Athena says:

    Andy, I agree. Orion is a beautiful constellation and it would be sad to see it lose one of its brightest stars.

  9. Athena says:

    The Rich poem has been part of my core literature ever since I read it. I did not include two stanzas in the middle, to keep the focus on Orion. Her images remind me of Lucifer, Prometheus and all the other defiant half-gods.

    I’m sure you’re right about the distance for lethal supernova radiation. I think 25 ly is the estimate for type II supernovae, which is the expected outcome for Betelgeuse. No matter what, though, we would not have two suns in our sky (as was the title of several “news” items about this topic).

  10. r0ck3tsci3ntist says:

    I wondered if you would comment on the long predicted demise of Betelgeuse! Personally, I’ve been thinking about for a while now. On one hand I would love to see a supernova so close, but on the other I will mourn the loss of the Orion constellation like an old friend.

    As I’m sure you know, the eventual demise of Betelgeuse is something astronomers have seen coming for at least fifty years. The whole 2012 thing has just given scaremongers something to capitalize on.

    Now I haven’t looked into this recently, but as I understood it, Betelgeuse was not actually considered to be a star that was originally massive enough for a true supernova event. It was understood to be in the supergiant stage at the end of normal star development. It was thought to be originally not much more massive than Sol, our star, and that its voluminous outer layers would dissipate to form a “planetary nebula”. Of course, our knowledge is constantly evolving so it seems that we have gained new insight into this enigmatic object. Also, as I understand it, the it’s the mass and orientation of the star more than it’s proximity that determines the potential danger to earth. Eta Carinae, for instance, would pose a much greater threat, being much more massive and unstable. It’s also bound to go at any moment. Fortunately, earth seems to be out of its orientation as well. Which is good news, (for all that we could do anything about it). ;)

    That poem was sublime as well. I think, perhaps I would mourn the loss of Diana’s lover from the sky as much as the goddess herself.

  11. Athena says:

    I, too, will mourn the loss of Betelgeuse if it happens in my lifetime. At the same time, explosions of this kind liberate the heavier elements that play such a vital role in complex life.

    The average calculated mass of Betelgeuse is 20 solar masses, well above the 1.4 Chandrasekhar limit for it to become a type II supernova (and it doesn’t have a binary companion that’s cannibalizing it). The explosion type also dictates the distance across which its radiation would be lethal (the 25 ly I mentioned in the article). But as both you and I said, the orientation is equally crucial. Such an explosion is posited by some to have caused the Ordovician-Silurian extinction event, 450 million years ago.

  12. r0ck3tsci3ntist says:

    20 solar masses! Yes, definitely supernova material.

    I will miss our striding Egyptian/our noble hunter, but yes, his demise will seed the molecular clouds of the future.

  13. antibozo says:

    Ford Prefect was not specifically from Betelgeuse; he was from “a small planet somewhere in the vicinity of Betelgeuse”.