The cold, thin, glorious line of star birth

By Phil Plait | April 14, 2011 7:00 am

At the end of May, 2010, the European Space Agency’s orbiting Herschel telescope was pointed toward a dark cloud in space over 2500 light years away. What it saw may solve a bit of a scientific mystery… and is also truly beautiful:

[Click to ennebulanate.]

This object is called IC5146, and consists of the Cocoon nebula on the left, and two long streamers of gas extending to the right. Herschel is very sensitive to cold dust in the very far infrared; in this image blue shows gas and dust emitting at a wavelength of 70 microns (the reddest color the human eye can see is roughly 0.7 microns), green is 250 microns, and red 500 microns — that’s over 700 times the longest wavelength light the eye can detect.

The Cocoon nebula is a well-known gas cloud being lit up by a massive, hot star in its center. In the visible light image inset here — grab the stunning high-res version to compare to the Herschel shot — the dust is dark, since it absorbs the kind of light we see. Also, stars are pretty faint at these extreme infrared wavelengths, so they don’t interfere with the observations of the gas and dust. That’s why observatories like Herschel are so important: they allow us to investigate objects that might be invisible to other telescopes.

As you can see in the Herschel image, the entire region is interlaced with long, thin filaments of dust. This dust is cold: much of it is only about 15° Celsius above absolute zero, or -430°F! What’s so very interesting is that the filaments, no matter what length they are (and as seen in other parts of the sky by Herschel as well), seem to have about the same width of roughly 0.3 light years across. That argues very strongly that these filaments are formed from turbulence in the dust, probably caused by exploding stars roiling up the matter between stars. That width is just about what you’d expect as shock waves from exploding stars slam into each other, interact, and become turbulent.

Looking at other filaments like these in other parts of the sky, astronomers also found about 100 dense knots of dust that are forming into stars in the filaments. This shows clearly that these filaments are the sites of star birth, something that was unclear before these Herschel observations. Not all filaments form stars, but the fact that some do will help astronomers understand the fiercely complicated mechanics of star formation.

These filaments are all over the sky; the image here from Herschel is actually of a region on the sky near the star Polaris (click to get a much bigger, very cool picture), which I would’ve thought would be nearly empty of dust. But clearly there are filaments galore there, and again they show that same characteristic width of 0.3 light years. Apparently supernovae have been going off all over the galaxy for quite some time, their expanding gas stirring up the ethereally thin material of interstellar space. In fact, these filaments are considered by astronomers to be dense, but the air in Earth’s atmosphere is hundreds of trillions times denser!

In astronomy, thin means thin. But over trillions of kilometers, even material that rarefied can eventually condense from gravity and form mighty stars.

The Universe is a lesson in superlatives, from thin to dense, from huge to huger, from chillingly cold to searingly hot. And, as usual, the beauty of the images themselves is rivaled by the beauty of the science and knowledge we derive from them.

Image credits: Herschel IC5146: ESA/Herschel/SPIRE/PACS/D. Arzoumanian (CEA Saclay) for the “Gould Belt survey” Key Programme Consortium; Herschel Polaris region: ESA/Herschel/SPIRE/Ph. André (CEA Saclay) for the Gould Belt survey Key Programme Consortium and A. Abergel (IAS Orsay) for the Evolution of Interstellar Dust Key Programme Consortium; Optical image: Adam Block/NOAO/AURA/NSF


Related posts:

The cold arms and hot, hot heart of the fuzzy maiden
A hole in space… no really, an actual hole!
Chaos! Turbulence! Blowouts! Herschel!
Herschel eyes the infrared Southern Cross
Herschel opens its eye

Comments (19)

  1. Boris Johnson

    Heya Phil, the link to the visible light image doesn’t work. It’s funny how images that are made from wavelengths the human eye can’t see are usually fantastically lovely. The grass is greener on the other side I guess!

  2. Anchor

    This is positively magnificent! I’ve spied the Cocoon (IC5146) and its peculiarly ‘starless’ tail often over the last 40 years through telescopes up to 20-inch aperture…and this Herschel image beautifully crystalizes what I could only imagine being there. Thanks for posting it Phil! Wonderful!

  3. Boris- thanks, it’s fixed.

  4. daninthai

    ” in this image blue shows gas and dust emitting at a wavelength of 70 microns (the reddest color the human eye can see is roughly 0.7 microns), green is 250 microns, and red 500 microns — that’s over 700 times the longest wavelength light the eye can detect.”

    Is it just me or are the numbers off?

  5. toasterhead

    I’m a bit confused by the “green is 250 microns, and red 500 microns” bit in your post. Visible light is usually measured in nanometers, isn’t it? 250 microns would be a wavelength of 250,000 nm, which puts it in the far infrared. Or do you mean that the green and red colors in the image translate to 250,000 nm and 500,000 nm far infrared wavelengths?

    Edit: Ok, I got it. You were talking about the false colors in the image, not the actual wavelengths for red and green and blue. Just took me a while…

  6. Toasterhead, I had the same brief confusion. :)

  7. MRNUTTY

    I love Astronomy, and this site is a great portal to some of the the BEST! However, being color blind; I wish red and green wasn’t used to prolifically. I can’t discern these red filaments from the rest :(

  8. Jim Shaver

    Boris, don’t you mean the gas is greener on the other side? :)

  9. Keith Bowden

    @daninthai
    500/.7=714.286
    714>700
    :)

  10. Minos

    I’m getting some great pareidolia from that image. My brain is stuck seeing it as a demon shooting a fireball from outstretched hand.

  11. Joseph G

    @Minos: Oh, now I see it! Badass(tronomy)!

    The thing I don’t quite grok is how there can be turbulence in such rarefied gas. How can there be low-pressure areas in the center of vortices, for instance, in something so close to a vacuum?

  12. Messier Tidy Upper

    Superb pyschedelic images. Excellent fascinating science. 8)

    Great closing paragraph :

    The Universe is a lesson in superlatives, from thin to dense, from huge to huger, from chillingly cold to searingly hot. And, as usual, the beauty of the images themselves is rivaled by the beauty of the science and knowledge we derive from them.

    ^ This! ^ Spot on. :-)

    Thanks Herschel team and BA. :-)

  13. Messier Tidy Upper

    @10. Minos Says:

    I’m getting some great pareidolia from that image. My brain is stuck seeing it as a demon shooting a fireball from outstretched hand.

    Pareidolia~wise I can see a demonic face in the lower image – an upside down pyramid with horns, mask like and with either a long nose or an outstretched tongue. Plus a screaming moai (easter island face statute) thing in the top right hand corner! :-o

  14. Messier Tidy Upper

    These filaments are all over the sky; the image here from Herschel is actually of a region on the sky near the star Polaris.

    Is that “near Polaris” in apparent terms – ie. as seen in Earth’s skies?

    Or is that “near Polaris” in the geography of our galaxy – ie. physically near Alpha Ursae Minoris (a.k.a. the Pole star, the North star, Polaris) in space itself?

    Does anyone know and care to enlighten us all, please?

  15. Charlie

    So.. what makes the streamers? Is the nebula moving to the left? Relative to what? Is there something massive off to the right pulling matter off the nebula? Something very bright off to the left exerting light pressure? I’m very curious!

  16. Messier Tidy Upper

    BTW. Polaris itself :

    http://stars.astro.illinois.edu/sow/polaris.html

    is a celestial beacon – a low-amplitude Cepheid variable that has been behaving very unusually :

    http://www.universetoday.com/15831/polaris-brightness-variations-are-revived-astronomers-mystified/

    to the point where it has almost stopped pulsating completely.

  17. Victor Bogado

    @Boris

    I would suggest two explanations for this, the first one is that images made from non-visible light are always made by humans to enhance the details and make “stuff” more clear to the viewer. In other therms they are constructed from data and while are you constructing something you may as well make it beautiful. If you like to follow the visualization field of computer graphics you can see many beautiful images and movies (all made from data).

    Another possibility is that we are not used to see the stuff, so even if there is only minor adjustments, like for instance a long exposition of the sky, it shows us something that we are not used to see, so it amazes us.

  18. JMW

    @10 Minos…

    You cannot pass!

  19. Wzrd1

    I’m curious and it’s not yet been answered, once stellar “ignition” occurs and heat finally is expressed toward the surface of the protostar, making it a main sequence star, should there not be a shockwave of thermal impulse visible that would impact the nebula?

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »