Gorgeous globular hides hundreds of rejuvenated stars

By Phil Plait | October 3, 2011 11:30 am

I will never, ever get tired of insanely gorgeous images of globular clusters.

Holy. Haleakala. [Click to embiggen, or get the ridiculously huge 3900 x 4000 pixel version.]

That is Hubble’s view of M 53, a cluster of several hundred thousand stars crammed into ball about 60,000 light years away — well outside the Milky Way itself, but bound to it, orbiting our galaxy. It’s probably 12 billion years old, but it looks like some of the stars in it have opted for a little cosmetic surgery…

In our galaxy, stars are so far apart that collisions between two of them almost never happen. But in globular clusters stars are so closely packed that many of them have apparently literally collided with each other, merging into objects called blue stragglers. Globulars are old, so having blue, massive stars is weird; they have short lifespans, and should’ve all blown up as supernovae or at least turned into red giants billions of years ago.

When these objects were first discovered in globulars they were really surprising, and while we still don’t understand everything about them, it’s a fair bet they result from two stars having a very, very close encounter. If two older, low mass red stars pass close to each other at low speed, their gravity can cause them to become bound to each other (it helps if a third star is involved; it can steal away energy from the other two, making it easier for them to become stuck together). Over time, they can spiral together and merge, forming a single, more massive, hotter object: a blue straggler. They’re seen in many globular clusters, and tend to be more common where stars are thickest, as you’d expect.

Over 200 of them have been found in M 53 alone, and at first glance, if you didn’t know better, you’d think they were far younger than the ancient stars around them. In a way, I suppose, they are.

But don’t judge. If you were a 12 billion year old star, you might want a facelift, too.

Image credit: ESA/Hubble & NASA

Related posts:

Lonely sentinel of the galaxy
The new VLT Survey Telescope delivers spectacular images
Spectacular and sparkling, but what is it?

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (27)

Links to this Post

  1. M54 where are you? « History is made at night | October 4, 2011
  1. Naked Bunny with a Whip

    Did Phyllis Diller take over this article at the end?

  2. MrCompletely

    ha, I didn’t know about blue stragglers. That’s awesome. Wiki only mentions them in this cluster context, are there no other equally crowded star forming regions in galaxies, near the core or suchlike?

    Wonderful color in the largest version of that image. Crystalline.

  3. Andrew

    I don’t know/doubt if I’m the first to ask this, but there should be some kind of ap/pc program that just downloads these when they are posted and sets it as wallpaper. Any programmers follow this blog might be willing to throw something together? Or anyone know of one that already exists in some form? I doubt (with no basis whatsoever for saying so) it would be overly complicated.

  4. Ian

    Amazing. First thing I saw through a telescope was a globular cluster. After that they became my personal favorites. So MANY stars!

  5. They say you learn something new every day. I learned about Blue Stragglers, so I guess my day is done! :) Thanks.

  6. Relativity

    Interesting as always Phil.

    If two (or more) stars formed one of these blue stragglers, will their lifespan now become what a normal blue star would experience and die off (in a supernova, of course) in a few or hundred millions after the merging event? Or would they continue to be a long-lived, but bigger and brighter version of their old selves?

  7. johnthompson

    Well, as they say, NOT EXACTLY: even in the cores of globular clusters, direct collisions (where the photospheres of the stars actually touch) are extremely, extremely rare. The two ways in which blue stragglers CAN form involve a) NEAR collisions in binary (or larger) systems where stellar exchanges and all matter of weird interactions are possible (single stars coming close to each other and forming a binary is impossible due to conservation of energy and angular momentum, unless a third object is involved) and b) “normal” mergers of close binaries as angular momentum is shed thru mass loss from the system (and some also thru gravitational radiation). The FK Comae stars found in the field are thought to be formed in this manner. Still a very pretty image though it would be nice to know how big it is on the sky (if one “clicks thru” you can find that it’s 3.4 arcminutes on a side)..

  8. Robin

    Man, this place is huge, but it has great lighting!

  9. “Click to embiggen…..”

    Surely old bean, you meant to say “Click to englobulinate…”

    Oh yes, spectacular image.

  10. John

    This image makes me think of Asimov’s Nightfall.

  11. MadSciKat =^..^=
  12. James

    To paraphrase a very wise and interplanetary traveler: “When 12 billion years old you reach, look as good you will not.”

    This is so my new desktop.

  13. Jess Tauber

    Are masses of blue stragglers ever large enough to produce a supernova?

  14. Musical Lottie

    Wow. My jaw actually dropped.

  15. Trebuchet

    I was surprised it took until no. 10 for someone to mention Nightfall! Gorgeous.

  16. Wzrd1

    The thing’s hollow—it goes on forever—and—oh my God—it’s full of stars!

  17. Brian Too

    @6. Relativity,

    I feel confident in saying that the merged stars (blue stragglers) will experience life as a short-lived blue giant. Assuming of course that they achieve the mass of a blue giant.

    Stellar lifespans are determined by the mass and temperature of the object. What they were before merging is of little consequence, unless both predecessor stars were very, very old and used up their hydrogen. Even then the consequence would simply be that the merged star would have an even shorter lifespan.

  18. Ganzy

    Beautiful! Another cosmic sparkler. For a long time I have wanted to fill an entire room wall in my home with a globular cluster like this. There are quite a few companies online now that will blow an image like this up, and print it onto wallpaper for you. The prices are reasonable now. Anyone know what kind of image size I would need, pixel-wise, to englobunate this onto a wall 4 metres by 2.4? Or is it just a case of the largest pixel image I can get hold of?

    When I get it done I’ll post a link to a pic.

  19. Wzrd1

    Well, the large size image is 16.6 megs in size. That should blow up nicely without excessive pixelation. Especially if interpolated, to prevent “zaggies”.

  20. Messier Tidy Upper

    I will never, ever get tired of insanely gorgeous images of globular clusters.

    Me either! 😉

    Superluminous image here. Love it! :-)

    That is Hubble’s view of M 53, a cluster of several hundred thousand stars crammed into ball about 60,000 light years away — well outside the Milky Way itself, but bound to it, orbiting our galaxy.

    Hmm … isn’t Messier 53 *inside* our Milky Way’s extended Galactic Halo region then? Our Galaxy doesn’t stop at the spiral arms and central bulge y’know! 😉

    Or does M53 actually orbit – at least partially – in intergalactic space outside of our Galaxy’s halo? Anyone know?

    If so, is that perhaps an indication that M53 formed around (or even was itself?!) another galaxy and has subsequently been captured by our Milky Way?

  21. Artor

    I’d love to see an animation of two stars colliding to make one of these “blue stragglers.” That would have to be one of the more spectacular sights the universe has to offer.

  22. Wzrd1

    Messier, why not? M54 was partially absorbed several times passing through the Milky Way, left a nice trail of stars.

    Artor, I dunno. Seeing two LARGE stars merging, then hypernova would most certainly be crazy cool!
    Watching a pair instability supernova would be cool too.
    But then, Scotty informed me, the new deflector shields won’t be installed until NEXT Tuesday. 😉

    Seriously though, think of two brown dwarfs joining and gaining sufficient mass to initiate fusion.
    THAT would be a sight to behold!

  23. Ganzy

    @19 Thanks Wzrd1, I understand what interpolation is now. It would have been disappointing to get the new wall paper delivered only to find it full of “jaggies”.

  24. Bob_In_Wales

    Actually, since two stars colliding and merging is REALLY REALLY unlikely, blue stragglers are proof that the Universe isn’t as old as Phil thinks it is! Maybe only about 6,000 years actually.

    Joking. JOKING!

    Personally I always find that it is pictures like this that begin to bring home to me what living in a universe of ~10^22 stars means. Thanks for the post Phil.

  25. Glissade

    Imagine the view from a planet orbiting one of the stars during such a merger.

  26. Back in my college days, I learned that globular clusters only undergo one wave of star formation when they first form, and never form new stars. Apparently, there ARE planetary nebulas and supernova nebulas that get blasted into space by stars within the globular cluster when they die — but the globular cluster’s in orbit around the center of the Milky Way, and every time the globular cluster passes through the plane of the galaxy the plane acts like a “strainer” and sucks all the gas and dust out of it.

    (Why and how the galactic disc does such a thing, I didn’t really understand.)

    Upshot: All the stars within a globular cluster formed at the same time, and the material they formed out of was very heavy-element-poor (i.e. all the stars are Population II), so there will be no space aliens living there. :-(


Discover's Newsletter

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


See More

Collapse bottom bar