C-beams off the shoulder of Orion

By Phil Plait | October 15, 2010 7:00 am

Orion is a morning constellation right now, high in the sky if you get up early enough. The three stars making the belt are obvious enough, and just below it hangs his dagger*. The middle star in the dagger is not a star, but a star-making gas cloud of mind-numbing size. There is much to see in the vast sprawl of its 5000 cubic light year volume, including young stars, still going through the pangs of birth.

One of these is the strange object called Herbig-Haro 502: a newly-born star shooting twin jets of material, far, far out into the nebula itself. Its beauty is simply breathtaking, as you can see in this spectacular image from Hubble:


[Click to ennebulanate to the giant 3800 x 3800 pixel version.]

Against the background gas of the Orion Nebula, HH 502, as those of us in the know call it, is almost lost — it’s the star just to the left of center wrapped in what looks like pink gauze (the jets are easier to spot in the full-res version). This image is a tiny, tiny fraction of the entire nebula, but the detail is exquisite. You can trace the jets of gas quite a ways. In real terms, the whole object is roughly a light year — 10 trillion km, 6 trillion miles — end to end. Neptune’s orbit would be a razor thin slice of a pixel on this scale.

There’s a lot to see. If you look carefully, you can see arc-shaped features all over the place. These are bow shocks, like the shock wave off the nose of a plane moving faster than sound. That’s usually caused by winds of gas screaming off of stars and slamming into the gas around it. Really elongated ones can be seen, too, and those are associated with the material firing away from the star at HH 502’s center.

Those jets are interesting: they are focused by a disk of material around the star far too small to be seen on this scale. But magnetic fields and other forces collimate the outflowing gas into those narrow beams. The flow of gas (which I found in a paper from 2001) is probably something like 400 km/sec (250 miles/sec), fast enough to cross the entire width of the United States in 15 seconds. The total amount of gas in the jets is something like 0.0001 times the mass of the Sun. That may not seem like much, but it’s the same as dozens of Earths! There are knots and clumps of gas, and astronomers have judged their ages to be around a thousand years. The jets are probably older than that, but probably not by much; they’re a short-lived feature of young stars.

hst_hh502_coreI got a surprise when I zoomed in on the central star in HH 502. I’ve shown the detailed image here. I expected to see the jet go all the way down to the star, but it actually appears to curve around it! What the heck…?

It’s not clear what’s going on, but I think what’s happening is that close to the star is a dense disk of dust – stars form from these kinds of disks. The gas in the nebula itself is flowing; you can see that a lot of the bow shocks are aligned such that the gas must be flowing from the lower left to the upper right. If you look at the HH 502 central star carefully, you can see on the left is another bow shock, and there is a tear-drop shaped flow around it with the pointy end to the right. The edge of the shock pattern is bright, and curves around the star. The jet itself is fainter near the star, so our eye blends it with the curved edge of the shock wave. I’m not positive about this, but that’s what it looks like to me.

In larger images, the jets are not completely straight; they can be seen to curve, like a bow. If the star is moving relative to the gas in the nebula, it’ll blow the jets back a little bit, a little bit like the plume of a volcano gets blown by atmospheric winds.

All this makes me wonder if the Sun looked like this, once, 4.55 billion years ago. There’s some evidence we were born in a gas cloud like this one, with dozens or perhaps hundreds or even thousands of other stars. Were we once swimming in a miasma of hydrogen, oxygen, sulfur, and nitrogen? Did our Sun shoot out twin beams of matter, tossed around by interstellar currents, blasted by ultraviolet light from massive stars, slammed by subatomic particles from their stellar winds?

It’s funny how we can know so much about other stars, but stuck here, billions of years in the future, we only know a little bit about our own star’s birth. But observations like this one from Hubble let us, at least, take a small glimpse into our past.

Image credit: ESA/Hubble & NASA. And yes, I know this isn’t technically off the shoulder of Orion; it’s more off his hip. But who can resist quoting Roy Batty’s magnificent final speech if given the chance?

* When I was in grad school, a friend of mine would snort in derision every time someone said that. "Sure, a dagger," he’d say.

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (34)


    Phil Plait:

    Orion is a morning constellation right now, high in the sky if you get up early enough.

    A real astronomer does not go to bed until sunrise! 😉

    P.S. Referring to the footnote, that friend of yours has a dirty mind!

  2. Nice Blade Runner reference! I think I need to pull the DVD out and watch it again, it’s been a while.

    Agree that your friend has a dirty mind. I think I’d like your friend. :)

  3. Bigfoot

    Oh no, miasma is flaring up again!

  4. hhEb09'1

    @IVAN PS, so those would be beams from his dagger, not off his shoulder

  5. Sometimes I think the Hubble scientists are artists. What a beautiful color combination.
    I know that is very unscientific of me to focus on, but come on. The first impression is one of beauty and a lot of that is the colors.

  6. MartiniConQueso

    I think you’ll find that Batty’s C-Beams were glittering in the dark near the Tannhauser Gate. It was attack ships on fire off the should of Orion . . .

  7. Messier Tidy Upper

    @ ^ Non-Believer : Agreed. There’s an art to science and science to art.
    The folks at the Hubble Space Observatory have both, methinks. :-)

    Seconding 2. Larian LeQuella on the Blade runner ref. Awesome movie. :-)

    Orion is a morning constellation right now, high in the sky if you get up early enough.

    I’ve just stepped outside, its midnight-ish here. Orion has just risen along with the Pleiades & Hyades in Taurus and Sirius is just getting above the trees. (My horizon is obscured.) :-)

  8. ahhh brade arunner…. you no eat 2, 1 enough.


  9. if you could see what i’ve seen with your eyes!

  10. Messier Tidy Upper

    Incidentally BA, do you recall taking any images of planetary nebula NGG 6826?

    Entirely by co-incidence, I was reading an old ‘Astronomy’ magazine earlier today & noticed this caption :

    “A giant star’s final act is blow off mass and form a planetary nebula. At left is the inner portion of NGC 6826 showing the bright central star, an inner rim of newly ejected material, and two outer knots. The photo at the right shows the nebula’s outermost halo. The bright blobs are probably areas where the expanding gas is colliding with denser regions in the interstellar medium. Photo courtesy Philip Plait and Noam Soker, University of Virginia.

    Source : Page 27, James Kaler’s article (series) “The Coolest Stars” in ‘Astronomy’ magazine, May 1990, Kalmbach Publishing.

    So .. I know it was a long time ago now but Phil was that you? Or is there another Phil Plait doing astronomy somewhere? 😉


    PS. In case folks are wondering the coolest stars are the wonderful Mira variables and carbon stars. Nowadays, of course we’d have to add brown dwarfs to that list. That was one of a series by Jim Kaler that I very fondly recall reading and which helped really inspire my interest in astronomy & stellar astronomy especially – so neat connection there! 😀

  11. Blade Runner quote FTW!
    Thanks for the post :)

  12. OK, I swear I’m not one of *those* people–I’m only doing this because I love the movie so much. The actual quote is: “I’ve seen things you people wouldn’t believe. Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tanhauser Gate. All those moments will be lost in time, like tears in rain. [pause] Time to die.” — http://en.wikipedia.org/wiki/Tannhauser_Gate

    Nonetheless, the reference was nicely made, and instantly evocative. Thanks for the explanation on the central star, too–very cool.

  13. Bart

    For the non-native-English readers in the audience, Phil has managed to use both “bow” (b/ah/w [shock]) and “bow” (b/oh/w [shaped]) in the same article. Way to homograph those heteronyms, Phil!

  14. C’mon, folks, who you talking to here? Of course I know the quote. But we’re talking beams of matter in Orion! And since the beams are bowed back, they’re C-shaped.

    Perhaps this might help.

  15. John Baxter

    Re, the footnote. I must take a fresh look at Orion, with different expectations.

  16. rt

    For insight into our own Sun’s past, we just need to ask someone very far away to take a peek and get back to us…

  17. Paul

    We simply used air quotes while saying the word “dagger”.

  18. James Morasco

    Phil continues to shoot WIN beams from his blog. Another job well done sir.

  19. Gorgious, looks like something out of a comic book =)


  20. Chris Webb

    Exceptional post, Phil. Thank you.

  21. Joel

    I love the Orion nebula. There’s so much going on in there. (Still bugs me that The Fountain got it wrong, though). I was banging on about this a few days ago, but it still astounds me that the nebula, big and impressive though it is, is just a tiny bright and concentrated section of the Orion Molecular Cloud, the size of which truly beggars belief – it covers most of the area of the visible constellation in the sky!

    On the other topic, never heard it referred to as a dagger before. Sword, normally.

    What we can conclude from this is that Orion dresses to the right.

  22. Navneeth

    I feel a sort of sense of peace when looking at the image. It’s not just the wispy clouds and the pleasing colours — there’s something about seeing the lone star and imagining the activity amidst all that. And imagine all that happening in silence.

  23. Brian Too

    Article and comment thread is superb!

    Hubble gotchu!

  24. Crudely Wrott

    All this makes me wonder if the Sun looked like this, once, 4.55 billion years ago. There’s some evidence we were born in a gas cloud like this one, with dozens or perhaps hundreds or even thousands of other stars. Were we once swimming in a miasma of hydrogen, oxygen, sulfur, and nitrogen? Did our Sun shoot out twin beams of matter, tossed around by interstellar currents, blasted by ultraviolet light from massive stars, slammed by subatomic particles from their stellar winds?

    I’d say that of all the occasions when stars like ours and HH 502’s progenitor form, some of them are amenable to what we could recognize as life. I’m pretty sure that at some time in the past our sun spent some time spewing dust and chucks outward from its poles. I have come to learn that there are few places within galaxies that are not subject to radiation of various frequencies at different amplitudes. At some time in the past our sun was young. Probably exuberant and wasteful, too. It may have been more energetic than we think or it may have been less. With more examination of data that determination will be made someday.

    What is certain is that the data seem to show that there is nothing special about the sun and that most of the stars we can examine are also not special. The vast majority of them.

    Is there life out there? Well, what should one suspect of a field sown with seed; one plant?

    Twenty five years ago I managed to focus a cheap 400 mm refractor on this very place in the sky. The advantageous looking of the sky from the Wind River Mountains in Wyoming were so good that night . . . whoa! . . .

  25. Tony

    I can not find the definition of “ennebulanate” anywhere – Is this a made up word by astronomers?

  26. Mike

    @Tony, I was about to ask the same thing. While I realize the word “embiggen” is perfectly cromulent, “ennebulanate” is a bit silly. However, the more I repeat it out loud, the more I like it. Testing out neologisms on us Phil?

  27. Liisa

    Soooo, what you’re saying is that there are hot jets of “fluid” shooting out from Orion’s “dagger”? *snicker* This is why I love astronomy. Do I smell an SMBC comic?

  28. Phil,
    Bally et al have a more recent paper on these objects with some nicer HST images:

    they have multi-epoch images, so it would be nice to get a movie (e.g. http://sparky.rice.edu/~hartigan/movies/hh111jetc.gif)… but I don’t think anyone in our group has the expertise.

  29. Joel

    @26 Mike: Have a look back through the archives. Phil does this sort of thing a *lot*. All seems pretty cromulent to me.

  30. Messier Tidy Upper

    @ 26. Mike :

    Testing out neologisms on us Phil?

    That’s what we’re good for isn’t it? 😉

  31. Soren

    Well I think Phil should stop having so much astronomy on his blog and more blogging about … cute babies and stuff!

    Seriously good post 😉


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