Hubble sees a gaseous necklace 13 trillion km across

By Phil Plait | August 12, 2011 6:48 am

I’ve been accused of having a big head (which is literally true; finding hats that fit properly can be difficult), but even I wouldn’t have any trouble squeezing the 13 trillion kilometer (8 trillion mile) wide Necklace Nebula around my noggin:

[Click to enlarynxate.]

This Hubble image shows the so-called planetary nebula, which is the product of a dying star. Deep in the center of the ring are actually two stars circling each other. As one started to die, it puffed up, literally engulfing the other star. This spun up the larger star, and the centripetal force flung off material in a huge disk well over a light years across. As the star lost its outer layers, the much hotter inner core was exposed, flooding the gas with ultraviolet light, causing it to glow like a neon sign.

Or, more accurately, a hydrogen/oxygen/nitrogen sign, the gases highlighted in this image (shown as green, blue, and red, respectively). See the knots of pink emission in the ring? As the gas was expelled, the speed of the wind increased with time while the density decreased. This faster wind caught up with and slammed into the slower wind, creating clumps and other features. You can see how the gas appears to be streaking away from the center of the ring; that’s real, as the fast wind carves away the slower one.

You can also see faint red blobs at the upper right and lower left, well away from the ring itself; those are probably the caps of a very faint (in this image, invisible) hourglass shaped nebula. The disk prevents the wind from expanding along the equator of the system, so it blows up and down, out, creating two lobes of material. Those caps are all you can see, where the gas gets mildly compressed at it expands into the gas surrounding the star system.

If this whole thing looks a bit familiar, well, it should: it’s very similar to Supernova 1987A, which I’ve written about a bazillion times (seeing as how I studied it for six years for my PhD). In this case, the central star(s) is lower mass, so not as hot as the explosion that flash-ionized the gas around the supernova. That’s why it’s fainter, even though at 15,000 light years away it’s actually ten times closer than 87a!

I love planetary nebulae. They’re weird, and pretty, and tell us a lot about how stars similar to the Sun die. In our daily lives death is rarely beautiful, but in astronomy it almost always is.

Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)


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Hubble sees spectacular star birth and death

CATEGORIZED UNDER: Astronomy, Pretty pictures, Top Post

Comments (29)

  1. Piper

    So many of the prettiest astronomical photos are in false colour, which I find somewhat disappointing. They wouldn’t look like that if you were actually there looking at it with your own eyes.

    You didn’t say whether this one is false colour. Since you described it as being like a neon light, I was curious whether the light would be visible. I looked up the wavelengths 0f the filters they used. They are all in the visible range, but the colours they assigned to them in the image are not their actual colours, so this is false colour too.

    I suspect if you used the real colours, it probably wouldn’t be nearly as pretty. And if you didn’t use filters at all, it would probably just look like a big white blob.

  2. @ Piper:

    Even when viewed with your own eye through the lens of a telescope, planetary nebulae are very pretty. Yes, they are for the most part colorless, but still…there is something about seeing these delicate little bubbles floating in the darkness, and knowing it’s the last gasp of a dying star, that elevate them to some of the most sublime visuals in the sky.

  3. Jonathan

    I think you might have gotten the color order backwards. I was under the impression that the emission band for nitrogen was green and the band for hydrogen was red/orange.

  4. Jonathan

    Nvm, I was thinking absorption bands, the opposite of emission bands. Nitrogen absorbs red light leaving it green. Hydrogen scatters green light, leaving it red. I realized my mistake a few minutes after posting.

  5. Jonathan- the folks at Hubble used odd colors to display the filters, and I checked; I listed them correctly. Usually H and Ni are red, so they colored them differently to distinguish them. Oxygen is usually green, but they used blue for it.

  6. QuietDesperation

    What is that in furlongs?

  7. oldebabe

    Wow! What a pic!. Just wow!

  8. Ed

    Cosmic Kirlian Photography! Or at least the Space Amoeba from Star Trek.

    ed

  9. Trako

    So that’s where my portal went in Portal 2 co-op.

  10. Gonçalo Aguiar

    13 Trillion kilometers… Omg if each dollar could count as a kilometer, the US national debt wouldn’t fit in it… o.O

  11. Captn Tommy

    Captian… It appears to be a giant amoeba.

    Can that be?

    That is what it says in the Script.

    My God, Scotty, get us out of here!

    Ey kenna due a thing Captain! En stoop callin me Goud.

  12. haversham
  13. @QuietDesperation Google says that 13 trillion km is equal to 6.4622604 × 10 to the 13 power furlongs ;)

  14. Tom

    Thanks for this cool post, Phil!

    I did a few calculations of my own. It seems that Neptune’s orbit is 4.5 billion km. So what we are seeing is 13 trillion km across, which is about 3,000 times the size of Neptune’s orbit. That gives it an identifiable perspective for me and I thought I’d share it.

  15. Brett

    Is there any way to guesstimate how many goldilock planets were destroyed during this event?

  16. @ ^ Brett : Not really. We still have no idea how many goldilocks planets exist to begin with so there’s a huge question mark there for starters. (Grand total so far : 1 known for sure – Earth – with another dubious possible candidate “Zarmina” or Gl 581 g unconfirmed – click my name for its wikipage. Plus I guess some of the Kepler sapce observatory’s candidates which are also unconfirmed as yet or so I gather.)

    I suppose we can the work out from the mass of the central star and its envelope and suchlike what type of star formed this nebula and if it was around the right spectral class during its main-sequence life (eg. late F – G – early K type dwarf) we can guesstimate its probabilities of having habitable planets.

    The shape of the nebula and whether any companion stars were involved can also be considered as factors in whether it used to have exoplanets and whether these could have been stable in the Goldilocks region or not.

    As for nearby exoplanets it seems unlikely the planetary nebvula would have too much of an effect on them given the vats gulfs of space separating stars (average around 3-5 light years if memory serves?) and their systems from each other and how rareified and thin the gas in the planetary nebula would be.

    Each stars stellar wind and magnetosphere would, I suspect, quite probably protect any habitable worlds it may have.

    OTOH, the ionising radiation may be a factor although this may also depend on how thick and effective a shield any hypothetical habitable world’s atmsophere might be.

    Given in our local stellar region only ahandfulof stars seem likely tohost goldilocks planets (Alpha centauri – 4.3 ly, Tau Ceti – 10 or so, Epsilon Eridani – 10 or so) I’m guessing the odds of such PN destroying habitable worlds are fairly low.

    ———-

    If you put three grains of sand inside a vast cathedral, that cathedral will be more densely packed with grains of sand than stars are found apart in space.”
    – British astronomer Sir James Jeans quoted on page 28, ‘Skywatching’, David H. Levy, Ken Fin Books, 1995.

  17. I’ve been accused of having a big head (which is literally true; finding hats that fit properly can be difficult), but even I wouldn’t have any trouble squeezing the 13 trillion kilometer (8 trillion mile) wide Necklace Nebula around my noggin

    I dunno, BA as a hat that nebula could ju-ust be a wee bit too big and thus too loose I reckon! ;-)

  18. Given in our local stellar region only a handful of stars seem likely to host goldilocks planets (Alpha Centauri – 4.3 ly, Tau Ceti – 10 or so, Epsilon Eridani – 10 or so) I’m guessing the odds of such PN destroying habitable worlds are fairly low.

    To be precise Tau Ceti – an old metal poor G8 yellow dwarf star :

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

    is located 11.9 light years distant with Epsilon Eridani – a very young K2 orange dwarf star – is located a fraction nearer at 10.5 light-years distant. (Link for that from the Tau Ceti link via Kaler.)

    There are only 3 stars known within 5 light years radius of our Sun – Proxima Centauri and Alpha Centauri A & B whilst going out to ten lightyeras adds only – Sirius A & B, Barnard’s Star, Wolf 359, Lalande 21185, the UV Ceti “Luyten’s Flare star” red dwarf binary and Ross 154. Almost all those are red dwarfs which may be extremely unlikely to host habitable planets – although OTOH :

    http://kencroswell.com/reddwarflife.html

    may have us rethinking that.

    So in a nutshell stars are pretty far apart and as this nebula extends “only” 8 trillion miles when a single lightyear equals 6 trillion miles. (Source : Wikipedia – lightyear page) it is unlikely it envelops more than its system of origin.

    Exoplanetary discoveries have been both positive when it comes to habitable “goldilocks” planets suggesting there are indeed many worlds out there – and also negative in showing that earthlike exoplanets and solar system anaologes are rare. We’ve been surprised by many exoplanetary systems that are hostile for habitable goldilocks planets due to Hot Jupiters (which may destroy earth-like planets as they migrate inwards) or eccentric orbiters (which again could disrupt any earth-like planets and force it too orbit to elliptically for likely life) or just the wrong planets in the wrong places such as here :

    http://blogs.discovermagazine.com/badastronomy/2007/08/03/new-planet-with-earthlike-orbit-nah/

    where an exoplanet, HD 17092, touted by some as having an “earthlike” 360 day orbit is in fact a superjovian orbiting a red giant star.

    (The more massive star which has 2.3 solar masses would have been probably too hot, too bright and too short-lived to host living planets even when it was on the main-sequence as a Sirian type star.)

    So, as noted we can’t really assess the odds of goldilocks planets being destroyed by this planetary nebula forming because we don’t really know yet how rare or common they are. We don’t know if this star that’s dying this necklace nebula case had any goldilocks type exoplanets itself – although that’s something that working out its mass and former spectral class could aid in – but it seems unlikely to me that it would kill off too many other worlds based on star populations and densities -and the fact, again, that space is big! ;-)

  19. Brett

    Thanks for that. Most informative.

  20. Navneeth

    “This spun up the larger star, and the centripetal force flung off material in a huge disk well over a light years across.”

    If the centripetal force is “centre-seeking”, then how could it have flung things out?

  21. Nigel Depledge

    Phil Plait (6) said:

    Usually H and Ni are red, so they colored them differently to distinguish them.

    Huh? I don’t remember you mentioning Nickel (Ni) in the article . . . ?

  22. Nigel Depledge

    @ Navneeth (22) –
    Every action has an equal and opposite reaction. Many physicists maintain that there is no such thing as the popularly-known “centrifugal force”, so it could be that the BA was simply implying that the reactive force to the centripetal acceleration was responsible.

    Either that or he meant centrifugal force.

    BTW, as someone who uses a centrifuge on a routine basis, I think there probably is such a thing as centrifugal force, even if it is fundamentally an illusion.

  23. @ ^ Nigel Depledge : Centrifugal force illusion / Centrifugal illusion of force maybe – or does that sound too Jedi? ;-)

    @23. Nigel Depledge : I’m guessing that ‘Ni’ is a typo for Nitrogen (N) rather than indicating gaseous clouds of nickel, surely?

  24. Captain Obvious

    It’s the Portal Nebula!

  25. Navneeth

    Hi Nigel Depledge

    Every action has an equal and opposite reaction. Many physicists maintain that there is no such thing as the popularly-known “centrifugal force”, so it could be that the BA was simply implying that the reactive force to the centripetal acceleration was responsible.

    Action-reaction pairs don’t act on the same object, so it’s not correct to speak of reactive the force of the centripetal force, which is already acting on the gas surrounding the star, acting on the gas as well. If anything, it should act on the star.

    Either that or he meant centrifugal force.

    I thought of that illusory force too. ;)

  26. mike burkhart

    This looks like a a parenecum (a protozoa,one celled animal) Thats what I like about nebulas they have interesting shapes,like clouds in the sky.

  27. andy

    This spun up the larger star, and the centripetal force flung off material in a huge disk well over a light years across.

    NO NO NO no no no no…

    The centripetal force is by definition an INWARDLY DIRECTED force. It CANNOT throw things outwards, this would violate Newton’s second law*. The centripetal force acts AGAINST the outward motion.

    Once again, since this point seems to be confusing: CENTRIPETAL FORCE IS AN INWARDLY DIRECTED FORCE.

    If we look at this in an inertial frame then it is inertia that is responsible for the material being flung outwards. Or we go to a rotating frame in which case you have to incorporate centrifugal force in the equations of motion, and it is the centrifugal force that throws the material outwards.

    (And yes we all get taught that centrifugal force is a fiction, but it is perfectly real in a rotating reference frame. Similarly general relativity demonstrates that gravity is also a fictitious force caused by the geometry of space-time but strangely enough no-one gets hang-ups about gravity being “not real”…)

    *Unless you are dealing with negative inertial mass that is, but this situation does not appear to be realised in the real world…

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