Rampaging cannonball star is rampaging

By Phil Plait | May 12, 2010 7:00 am

Need a refill on your cup of awesome today?

As someone who spends a lot of time thinking about astronomy and the weird stuff that happens on a daily basis in space, I see a lot of amazing things. You’d think I’d get used to the awesomeness of astronomy, but the opposite is true: I’m always spellbound by what I find.

Still, it takes a lot to seriously impress me, to really make me say Holy Frak.

Well, astronomers have just announced that they have found a massive star that has been flung out of the cluster in which it was born. The star is huge — 90 times the mass of the Sun — and is screaming away from its nursery at 400,000 kilometers per hour.

Holy Frak.

This incredible image is from the ESO’s 2.2 meter telescope in Chile. It shows an overview of the sprawling 30 Doradus star-forming cloud, located about 180,000 light years away in the satellite galaxy to the Milky Way called the Large Magellanic Cloud (or the LMC to those in the know). In the center of 30 Dor sits a vast cluster of stars called R136. The total combined mass of all the stars in R136 is unclear, but it has several that tip the cosmic scale at 100 times the mass of the Sun, which is the upper limit of how big a star can get without tearing itself apart.

The inset image is from Hubble, and shows the runaway star, named 30 Dor 016. It’s been suspected for some time of being a cannonball blasting its way across space away from the cluster, but new observations have pretty much clinched it. They’ve also pinned the mass of this star to that whopping amount of 90 times the mass of the Sun. If you don’t think that’s a big deal, I’ll note that this equals 180 octillion tons — that’s 180,000,000,000,000,000,000,000,000,000 tons, for those of you who have stock in the ASCII character for "0".

Yeah. Holy Frak.

The new observations, using Hubble’s new ultraviolet camera called the Cosmic Origins Spectrograph, confirm that this is a single star (and not, say, a binary with two members each with 45 solar masses), making it one of the most massive stars ever seen. This kind of star is extremely rare!

The UV observations also confirm that the star is plowing through the gas that lies in interstellar space in the LMC. You can get a good idea of what’s going on in this closeup of the star:

hst_runawaystar_zoom

It’s moving to the upper right in this image. You can see it’s near the edge of a curved bubble of gas, with a sharp edge delineated to the right of the star. That edge is a bow shock, a vast supersonic shock wave formed when the fierce wind of subatomic particles emitted by the star — a super solar wind – slams into the gas around it. If the star were just sitting there this bubble would be spherical with the star at the center. But you can see the bubble is actually elongated, and the star is near the edge. That’s a sure sign we’re looking at a star on the move.

Amazingly, it appears that the star is 375 light years from the cluster! A star this massive can’t live very long, a few million years at most. At 400,000 kph, it takes about a million years to travel that distance, so that fits.

How the heck can you kick a star up to such incredible speeds? There are two ways we can think of: have it tossed around by the gravity of other stars in the cluster, or have it ejected when (if it’s a binary star) its companion explodes as a supernova.

For the latter supernova scenario, it’s not the explosion that accelerates the star, it’s the slingshot effect. The two stars orbit each other at high speed, and when one blows up it loses so much mass it can’t hold onto the other star. Like an athlete spinning around for the hammer toss and then letting go, the star gets shot away at high speed. The thing is, the cluster itself is too young to have seen such a supernova a million years ago, when the star must have begun its flight. Plus, there’s no indication of the type of a mess left by such an explosion.

So the star must have been ejected when it reacted gravitationally to other stars. If you take three stars, say, and let them interact, the least massive one will get flung away. Take a few dozen and you get a beehive of activity, with several stars tossed out, some with very high speed. The thing is, this star has 90 times the Sun’s mass! That means the stars left behind are even more massive… and we do see several stars in the cluster with masses as high as 100 – 120 times that of the Sun.

Yeah again. Holy Frak.

So let me explain… no, there is too much. Let me sum up.

We have a stellar cluster with thousands of times the Sun’s mass embedded in a nebula furiously cranking out newborn stars. A lot of them are near the physical upper limit of how big a star can get. The whole thing is only a couple of million years old, a fraction of the galaxy’s lifespan. One beefy star with 90 times the Sun’s mass got too close to some other stars, which summarily flung it out of the cluster at high speed, fast enough to cross the distance from the Earth to the Moon in an hour (it took Apollo three days). The star is barreling through the flotsam in that galaxy, its violent stellar wind carving out a bubble of gas that points right back to the scene of the crime, nearly 4 quadrillion kilometers and a million years behind it.

Hmmm.

Y’know, there are days I have a hard time getting out of bed. The humdrum routine of the day yawns ahead of me… but every now and again, as I lie there mustering up the courage to throw off the blanket and face the world, I get a glimmer that maybe today the Universe will once again refill my tank, make me look above and outside me, and remind me that truly, the place is full of awesome.

Today was such a day.

Image credit: Hubble: NASA, ESA, J. Walsh (ST-ECF) Acknowledgment: Z. Levay (STScI). ESO image: ESO Acknowledgments: J. Alves (Calar Alto, Spain), B. Vandame, and Y. Beletski (ESO), processing by B. Fosbury (ST-ECF).

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (63)

  1. IVAN3MAN AT LARGE

    Phil Plait:

    If you don’t think that’s a big deal, I’ll note that this equals 180 octillion tons — that’s 180,000,000,000,000,000,000,000,000,000 tons,…

    Phil, is that “short tons”, “long tons”, or “metric tons” (tonnes)?

  2. znemo

    400,000 kps is 400000 kilometers per second? Speed of light is 300000 kilometers per second,
    correct me if I’m wrong.

  3. I don’t think you can really use the term “supersonic” in reference to a bow shock in space, can you? Since sound *doesn’t* travel in space, isn’t anything with V greater than 0 supersonic?

    But points for your Princess Bride reference!

  4. At the top of the post you said:

    “The star is huge — 90 times the mass of the Sun — and is screaming away from its nursery at 400,000 kilometers per hour. ”

    Then a little further down you said:

    “At 400,000 kps, it takes about a million years to travel that distance, so that fits. ”

    I presume “kps” is referring to “kilometers per second”, so… is it 400k kph or 400k kps? :)

  5. Brett,

    I’d imagine the former, lest stars be in the habit of breaking the speed of light.

  6. chimango

    Phil, and the day is not over yet. What do you think about this? —> http://arxiv.org/abs/1004.5379 (as seen in here: http://news.bbc.co.uk/2/hi/science_and_environment/10108226.stm )
    cheers!

  7. You forgot a third method of propelling it: load it into a really, really big gauss rifle (for all those EU/PC fans out there).

  8. Our own sun was likely formed in a cluster or with siblings… has research shown which stars might be from the same “family” as the Sun?

  9. Gary Ansorge

    3. David W.

    True, in space, no one can hear you,,,unless there’s something IN that space, like gas, which is exactly what we have here. Granted, the gas molecules are spread far apart, so our ears wouldn’t receive enough energy from those rare molecules to hear anything, but a star, planet or another gas molecule traveling at 400,ooo kph will ram into a bunch of molecules every second, which is how sound is transmitted, as a transfer of kinetic energy from one molecule to another.

    Can we tell the approximate age of the star? Is it about to go super nova(from our perspective, that would make one impressive light show)? I’ll get the popcorn.

    8. Evolving Squid

    We’re still looking for that nebula.

    Gary 7

  10. PsyberDave

    I’d be interested in seeing an animated series of pictures taken over several years.

  11. @znemo actually, the speed of light is exactly 299,792,458 m/s :D

  12. Chip

    to quote the kid at the end of “The Incredibles” — THAT IS TOTALLY WICKED!

  13. riki

    Stars could possibly get bigger (300 solar masses) in dwarf galaxies where there is less heavy elements.

  14. Art

    Stop motion video would be awesome!

  15. Tom

    You said: ‘physical upper limit of how big a star can get’. What is this limit? Why is there a limit? I mean, more massive stars also tend to be less dense (or so I believe based on what I read) so why is there an upper bound? My thoughts would be that more mass == black hole but that gets lost with the less dense options so I am lost. I figure bigger stars burn faster and then blow up bigger, but what’s the deal with the upper limit?

    Thanks,
    -Tom

  16. Blaidd Drwg

    “Supersonic”? Come on, everybody knows it is physically impossible to travel faster than the speed of sound! Chuck Yeager was a fraud!!!

    *end of snark mode*

  17. Quatguy

    I assume that in a few million years, the star will go supernova. It will be like a gynormous (its a scientific word, look it up) firework in the sky, shot out at huge speed and then exploding. Hopefully it will go off on July 1 (Canada Day), or July 4 (for all you Yanks).

  18. rick king

    How do they know that star and not one of the other hundreds in the picture is one flung out from the cluster?

  19. Theron

    Scibuff@11 said: actually, the speed of light is exactly 299,792,458 m/s

    Ha! That’s what those sneaky scientists want us to believe. Meanwhile, they’re grabbing up all the choice planets to build up their empires! Isn’t that right Phil? I think it’s time you came clean about that “super secret project.”

  20. Is this star moving fast enough for relatavistic effects to cause a notable change in its apparent lifespan compared to an identical star that hasn’t gone to Plaid? Let me get a stub of a pencil, an envelope, and that Physics degree I haven’t used in twenty years…

  21. #17 Quatguy: too bad there most likely won’t be any such thing as Canada, a Yank, or even July in a million years :)

  22. Quatguy

    #21 – Sad but most certainly true. We will be very lucky if there are still humans around. At least the cockroaches will get to enjoy the sight!

  23. Kyle

    @Harold: I don’t think so, if my math is correct its only going something like 3.7^-4 % of the speed of light. Rather pokey actually.

  24. Eric

    So if there are lots of stars there 90 solar masses and up, then this whole region should be lighting up with repeated hypernovas every few million years (or even every several hundred thousands of years).

    My, my.

    I’m glad we don’t live nearby.

  25. Gamercow

    Whoa, that thing is just the Duggar of star forming clouds, isn’t it?

  26. If the star was ejected due to a companion star going supernova, then wouldn’t the resulting nebula have dispersed by now? Don’t nebulas last only a few tens of thousands of years before blending into to the surrouding interstellar medium?

  27. Christine P.

    #16 Tom: The star’s growth bumps into the Eddington limit. Basically, the more massive a star gets, the faster it burns fuel at its core. That increases the amount of radiation it emits, and the radiation pressure that pushes outward and counteracts gravity. (All main-sequence stars are in this balancing act of gravity versus radiation pressure.)

    When a star is growing, as the protostar gains mass, the radiation pressure increases and pushes matter out, making it harder and harder to accumulate more mass. Anything that tries to fall onto the protostar gets blown off again. So, the star can’t grow any more massive.

  28. Anthony

    @Tom: The problem is with such huge stars the rate at which they fuse hydrogen and therefore produce energy is so enormous that the forces literally start ripping the star apart. It may also be difficult for a star of that size to form through the usual cloud collapse formation. This is just a general idea though from what I recall reading, I’m sure Phil can easily correct me on this one.

    edit: @Christine, thank you I couldn’t remember the name of the particular theory.

  29. Messier Tidy Upper

    WOW!!!

    Now. That. Is. IMPRESSIVE!

    Mind boggling star & even more mind-bogglingly to think it was the runt of the litter! ;-)

    I presume its a spectral type O-something- hypergiant and future LBV hypernovae like Eta Carinae or the Pistol Star I’d guess, right?

    Great write up and marvellous news there thanks BA. :-)

  30. Merijn

    @27: I’d guess that the renmants other than dust would still be visible in the shape of the surroundings.

    And indeed, if there’s 100 stars there with an average lifespan of 10 million years, you’d expect a supernova or even hypernova about every 100.000 years on average.

  31. Merijn

    As for sound progressing, if you think of sound as molecules hitting one other, even very thin clouds can exhibit sound waves if the speed is INCREDIBLY high so that the probability of molecules interacting gets a bit higher. If one molecule is than able to pass it’s energy to another molecule, that would be “sound” by this definition. The speed of sound would also be ridiculously high, but 400.000 km / hour is quite some speed, and I don’t know the speed of the solar wind that this monster may be able to produce…

  32. JMW

    Hm. Assuming that Phil’s first figure (400,000 kph) is correct, that’s about 400,000 / 300,000 / 3,600 of the speed of light, or 1.33 / 3,600 or 1 / 2,700 of the speed of light. About .0037c (doing all the math in my head, so please excuse me if I’ve erred).

    Relativistic effects (time dilation, foreshortening in the direction of travel, and mass increase) are governed by the relationship
    1 – ( v^2 / sqrt( c^2 – v^2 ) )
    or something like that, right? So with v still so small relative to c, there shouldn’t be much relativistic effect.

    Too bad it’s such a massive star. Were it a main sequence star with an inhabitable planet that supported intelligent life…but then, to them they’d be “normal” and we’d be the ones suffering the relativistic effects.

  33. Lucas

    I remember reading that our sun moved at about 50 km/s around the galaxy.
    Is this correct, or is my memory confused (as usual) ?
    If that is correct, isn’t 111 km/s (400000 km/h) a bit low for such a surprise?

  34. AliCali

    Lucas:

    The big deal is that the star is moving fast relative to the cluster in which it was born. In the Sun’s case, our star is moving at about the same speed of nearby stars around the center of the galaxy, so relatively speaking, we’re going with the flow.

    Also, Dr. Plait surmises that the massive star is moving away from thej cluster because it was ejected by stars that are even more massive. Since the runaway star is already near the upper limit, it’s amazing that the original home has stars even bigger and can exert such a force on so massive an object.

  35. George

    Phil,

    This star actually displays proper motion?

  36. Pi-needles

    If you don’t think that’s a big deal, I’ll note that this equals 180 octillion tons — that’s 180,000,000,000,000,000,000,000,000,000 tons, for those of you who have stock in the ASCII character for “0″.

    Hmm .. you can buy stock in numerals? Think I’ll buy lots of zeroes & ones and see if I can get a monopoly on binary. Mwha-haha! ;-)

    @ MTU #30 :

    I presume its a spectral type O-something- hypergiant

    Spectral class O0 pronounced “Uh-Oh” maybe! ;-)

  37. Messier Tidy Upper

    @16. Tom Says:

    ‘physical upper limit of how big a star can get’. What is this limit? Why is there a limit?

    Its called the Eddington limit as Christine P. (# 28.) has explained nicely & exists because a star is what you get when you have a stalemate between gravity trying to squash matter in and radiation pressure trying to blow matter-energy out.

    Also as noted, really high mass stars tend to be very rare because they are hard to form in nature particularly now.

    There was a period early in the universe’s history when the very first stars (‘Population III’) formed when this wasn’t the case as having a “metal-free” cosmos made things very different and back then stars of up to 300 + solar masses might have been briefly commonplace. However, this is theory and yet to be confirmed as far as I’m aware.

    However, today now and especially in our metal-rich Galaxy super-high mass stars are very uncommon – with 90 % of all stars being less massive than our Sun. Less than 1% of all stars now are the high-mass O & B spectral classes and about 80% are either red or orange dwarfs. (Another 10% or so are white dwrafs and about 5 % are G & F stars – not sure what the %-age of brown dwarfs is.)

    See : http://en.wikipedia.org/wiki/Eddington_limit

    I mean, more massive stars also tend to be less dense (or so I believe based on what I read) so why is there an upper bound?

    Tend to, yes but mostly when they are “late type” evolved stars eg. red supergiants and giants.

    Higher mass stars can start out denser and hotter too I think but once they evolve their outer layers become distended, extend out to the equivalent of the orbit of Saturn here or more and get so tenuously thin they are described as “red hot vacuum.”

    My thoughts would be that more mass == black hole but that gets lost with the less dense options so I am lost. I figure bigger stars burn faster and then blow up bigger, but what’s the deal with the upper limit?

    Yes – bigger stars live *much* shorter lives. A million or so versus ten billion for our Sun.

    Thanks,

    No worries – hope you see this & it helps. :-)

  38. Messier Tidy Upper

    Its called the Eddington limit as Christine P. (# 28.) has explained nicely & exists because a star is what you get when you have a stalemate between gravity trying to squash matter in and radiation pressure trying to blow matter-energy out.

    Oops – I forgot to add :

    If the gravity wins the star crushes down into a black hole as happens to a higher than 3-4 solar mass core of a star gone supernova. (A type II or “core collapse” supernova anyhow.)

    If radiation pressure wins then the star literally cannot hold together and radiates (“shines”) so powerfully that it tears itself apart.

    Radiation pressure “winning” may explain the outbursts that some super-high mass stars like Eta Carinae and the Pistol Star undergo where they shine immensely brightly and eject a lot of matter (mass-loss episode) which can create spectacular nebulae before the stars settle back to their still extreme state.

    (See : http://en.wikipedia.org/wiki/Eta_Carinae )

    These high mass stars can also lose so much of their outer layers through their powerful stellar winds (think the solar wind massively supersized! ;-) ) that their cores are stripped bare and they don’t become red supergiants – instead becoming what are known as Wolf-Rayet stars. (http://en.wikipedia.org/wiki/Wolf-Rayet_star)

    Personally, I find such high-mass superluminous stars, their behaviour and evolution, fascinating and it’s one of my favourite astronomical subjects. :-)

  39. mfumbesi

    Thank you for the explanation.

    The other stars conspired against this poor guy and threw him out of the nest.
    Shame on them.

  40. Messier Tidy Upper

    PS. Kudoes to Anthony (#29) as well Christine P. (#28) for their excellent replies to Tom’s question as well. :-)

    @ 37. Pi-needles :

    Spectral class O0 pronounced “Uh-Oh” maybe

    Oddly enough, I think I’ve heard that we don’t know of any star that is classified as having a spectral class that’s “bluer” /”earlier” / “hotter” / “more massive” than type O3. Is that true anyone know?

    What *is* the spectral type of 30 Dor 016 – this 90-solar mass runaway star?

  41. Jeeves

    That’s a whole lot of m v squared. Even if you divide it by 2.

  42. It doesn’t have to be the lightest to be ejected. Say you have three stars. Two of them form a binary. They pass near the third. The third captures one of the binary. The other gets flung out at high speed. It helps if the one getting flung out is lighter, but it isn’t required.

    Remember, three out of every two stars is a multiple star system.

  43. vilms5000

    s/awesome/jawdropping

    Thanks for the post!

  44. Krat

    Wow.

    An exercise in geekimus maximus.

  45. Just me

    Okay. Something I’ve never quite understood. I’ve heard numerous accounts of gravitational interactions causing things to be “thrown out” of a system. But gravity is an attractive force. So, how can an object that gets too close to other objects get thrown out?? Can someone explain this to me in “captain dummy talk”?

  46. Jonsse

    Light moves at 300 000 kps, the star is moving at about 1/2700 of light speed.

  47. gK

    I am wondering if this star would have planets while its bolting across the space?

  48. So… before long it will be a rogue black hole rampaging through the universe, ripping planets from their orbits, eating stars and throwing others out into space like this one does now.

    AWESOME! Or, at least it is when I’m not in it’s path.

  49. Messier Tidy Upper

    @ 48. gK Says:

    I am wondering if this star would have planets while its bolting across the space?

    Sadly, this star – 30 Dor 016 – is exceedingly unlikely to have exoplanets orbiting it on three major counts because :

    1) 30 Dor 016 is an extremely short-lived, super-high-mass star which means planets won’t have had enough time to form and the intense stellar winds would probably have blown away any protoplanetary (planet-forming) disk.

    2) The environment 30 Dor 016 formed within a cluster of other hot, superluminous, supermassive O type stars which means that not only would 30 Dor 016′s *own* stellar winds & outflows have disrupted any protoplanetary disk but so too would the similar or worse stellar winds & outflows of a whole lot of other even hotter and brighter O type stars too – including its former, larger & hotter companions.

    (NB. The intense UV radiation from less gargantuan O type stars in the Orion nebula star-forming region has been observed to strip away and destroy protoplanetary disks around other stars in that region.)

    3) The ejection process means that any planets around 30 Dor 016 (*if* they could have formed and existed to begin with) would have been cast adrift or thrown into unstable orbits by the other stars when 30 Dor 016 was gravitationally ejected from the system.

    @ 46. Just me Says:

    Okay. Something I’ve never quite understood. I’ve heard numerous accounts of gravitational interactions causing things to be “thrown out” of a system. But gravity is an attractive force. So, how can an object that gets too close to other objects get thrown out?? Can someone explain this to me in “captain dummy talk”?

    Okay, I’ll have a go for you.

    Gravity attracts and acts like a well where things fall down towards the bottom reaching (hence the term “gravity well”) But this “well” has no bottom – just a small sphere in the centre so things pick up speed and fall through if they miss that sphere causing the gravity.

    Not just that but there’s more than one such “well” moving around so as the star picks up speed “falling” towards one “hole” it is thrown out and, maybe, thrown towards another where again it is slingshot further and eventually all the way out of the cluster at high velocity.

    Or think of a ball on a billiard or snooker table with a magnet that attracts another ball. If the second ball is travelling slowly, it will be drawn into contact and stick to the “magnet ball” but if it is hit much harder, it will bend towards the magnet ball but have too much velocity to “stick” and keep going on an altered path or bounce off at a higher speed.

    Does that make any more sense for you now, ‘Just me’? Hope those analogies help. :-)

  50. Messier Tidy Upper

    Here’s one more analogy to help visualise the situation :

    Imagine a tunnel carved all the way through the Earth which is big enough to hold, say, a castle and right at the Earth’s core you have a horseshoe magnet – about the size of a beer coaster – that is occupying just a tiny bit of the tunnel right in the very middle but is emitting a very powerful magnetic pull.

    Now imagine you drop a iron sphere the size of an orange into this opening of this tunnel and you do so from the very edge. This ball plummets down picking up speed and, as it falls, the magnet pulls on it and alters its course. When the iron sphere reaches the centre, it just barely misses the horseshoe magnet by a coat of paint and because it is travelling so quickly, it rushes away far too rapidly to be drawn back and stick to the magnet which is already now far above it. The sphere keeps falling at an extreme velocity and shoots out the other end of this tunnel at vast speed. (Imagine you dropped it say at the north pole and the tunnel exits at the south pole or vice versa.) Except, because of the deflection by the magnet’s pull the iron ball which started on one edge of the tunnel now departs from the opposite edge instead.

    This may not be perfect analogy (&, yes, I hope the magnetism / gravity mix doesn’t add to your confusion – in this metaphor *both* the gravity of the drop into the tunnel and *ALSO* the magnetism of the magnet that deflects its path are standing in for the one *same* gravitational “attracting” force) but I hope it helps folks understand how the gravitational “throwing out” process works. :-)

  51. a dood

    I wouldn’t suggest trying to get close enough to hear it. O___O

  52. Peter D

    People keep asking for Stop Motion video, or a succession of pictures….it took the star a MILLION years to travel about 4 inches in the picture. How far do you really think that it would travel in the 50 year that we have had technology enough to even take the pictures in the first place. (I am being generous on the years)

  53. asimovy

    The single star isn’t moving at 400,000 kph the cluster of stars and gas are moving away from that star!

  54. Nathan

    Could the gas it is travelling near/through/behind be distorting the size of the sun as we see it from Earth?

  55. Toby Flenderson

    When mentioning measurements, can you please add real measurements like miles per hour?

    We don’t use the metric system in America, so it’s like nerds dropping Klingon words. It stops comprehension cold.

    Thanks
    (QA TLHO’ for you Klingon nerds!)

  56. How’s about this.

    Why not think of it this way.

    The star is stationary, and space is moving.

  57. Just me

    @ Messier Tidy Upper (50 &51)

    Thanks for the explanations. They were kinda what I thought, but I’m not a scientist. :-( I love science, but I get woozy and faint when I see mathematical equations. Sigh.

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