Sometimes a cigar galaxy is just a cigar galaxy

By Phil Plait | January 3, 2012 7:00 am

Astronomical imagery is a tricky business. Different objects behave differently, emitting light in different ways. So, for example, a cool dinky star might give off very little blue light — through a blue filter it virtually disappears — while a hot, massive star blasts out blue light. Your choice of filter can drastically change the way an object looks.

Having said that, I recognized right away that this image is the core of the nearby galaxy M82… but it still looks funny to me:

[Click to galactinate, or grab the huge 12.5 Mb image.]

One reason this new image from Hubble looks funny to me is that there aren’t as many stars in it as I expect. M82, also called the Cigar Galaxy due to its elongated shape, is pretty close as galaxies go, about 12 million light years away. It’s one of the closest large galaxies in the Universe, and a Hubble image usually shows it littered with stars, so closely packed they form a bluish background glow in most pictures.

And while that background of stars is there, it’s more diminished than usual because in this image astronomers used a series of filters that accentuate the light emitted by gas. While stars put out this kind of light as well, these filters downplay starlight and crank up the volume on, um, gaslight. Specifically, blue and green are from oxygen, red is from sulfur, and teal is hydrogen. The dark material is dust: long-chain molecules that absorb starlight. They also tend to redden light coming from behind them, similar to the way haze in the air makes sunsets look red.

Clearly, M82 is lousy with gas and dust in its core. That’s because it’s a starburst galaxy — it’s currently undergoing a fairly violent reproductive spree, cranking out new stars at a prodigious rate. This is probably due to a recent (well, if you can think of a few millions years ago as "recent", which astronomers do) collision with its neighbor M81, a gorgeous full-on spiral galaxy. The gravitational interaction sent gas clouds slamming into each other inside M82, collapsing them and forming stars.

A lot of these new stars are hot and massive (and blue, right?), blasting out tremendous winds of particles, like a solar wind on cosmic steroids. These combined superwinds are stirring up and blowing out the gas and dust in the galaxy, creating the amazing swirls and tendrils you see here. Young stars also make lots of dust (both when they form and when they die, exploding as supernovae), which is why there is so much of the junk floating in the center of the galaxy. Those tendrils go right out of the galaxy, stretching for hundreds of thousands of light years, as you can see in the inset image from Hubble of M82 from back in 2006 (click to embiggen).

Eventually, the starburst will subside, M82 will settle down a bit, and a lot of that gas and dust will travel into intergalactic space. This kind of thing happens all the time out in the Universe, and it’s kinda nice we’re able to get such a close view of it. Highly-detailed images like this one from Hubble can help us trace the location and behavior of all these baby stars and the turmoil they create.

And what better way to celebrate so many births than with a cigar 40,000 light years long?

Related posts:

M82 stifles a cosmic belch
In galactic collisions, might makes right
M81, up close and personal
AAS #6: Lonely stars between galaxies


Comments (9)

  1. Dragonchild

    “And what better way to celebrate so many births than with a cigar 40,000 light years long?”

    Well, you can. . . taste the rainbow. . .

    / try the veal

  2. Messier Tidy Upper

    Marvellous image – great to see the Monday galaxy tradition return. :-)

    People used to think Messier 82 was an exploding Galaxy. It may not be “blowing itself apart” as they used to think but it’s certianly a pretty superluminously impressive object :

    The starburst galaxy is five times as bright as the whole Milky Way [In absolute not apparent terms natch – ed.] and one hundred times as bright as our galaxy’s center. In 2005, the Hubble Space Telescope revealed 197 young massive clusters in the starburst core. The average mass of these clusters is around 2×105 M⊙, hence the starburst core is a very energetic and high-density environment. Throughout the galaxy’s center, young stars are being born 10 times faster than they are inside our entire Milky Way Galaxy.

    Source : , Emphasis added.

    Its also not an irregular galaxy as formerly thought but a spiral – looking cigar-shaped due to the angle we're seeing it from. Well, that northern hemispherers are seeing it from anyhow. Can’t see it from where I live, alas.

    You can see here :

    How different M82 looks at different wavelengths plus here :

    is a zoom-in youtube clip that could help folks find it. If they live in the right location that is.


    “Quasars are so luminous that if one was in action in a local group galaxy its brilliance would rival that of the Sun.”
    – P.284, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

  3. I really like the image that shows M81 and M82 in the same frame. Such vast distances all in one pretty picture. :)

    So, any discussion or thoughts on the central black hole for M82? With the “recent” collison, and all that dust and matter swirling around, how does that affect the activity of the black hole? And is the M82 black hole one of those intermediate sized central black holes I read about in this last Scientific American?

  4. Messier Tidy Upper

    Typical – just after posting those links for comment #3, I find this :

    & this :

    which are even better looks at the Cigar Galaxy including a reference to how it is indeed smokin’! 😉

    Then there’s this :

    whimsically titled item about an exceptional supernova finding in the Cigar galaxy -including a suggestion we could be seeing more of them – one every few years. Except for the spoilsport shrouding dust probably largely hiding them.

    Hope these links are useful / enjoyable for y’all. :-)

  5. Ken

    You may think this cigar galaxy is just a cigar galaxy. But in the 2006 image, I think it’s getting great penetration of those delicate red tendrils, causing an explosion of star birth.

    Sorry, I’m aFreud I couldn’t stop myself. OK, I’ll leave now.

  6. dcsohl

    In April 2010 astronomers found a new mysterious radio source in M82 that appeared to be moving faster than the speed of light. I can’t find anything after a brief update from December 2010 indicating that it was still active.

    Anybody know anything else about this?

  7. Yeah, I’ve always called it “The Exploding Cigar Galaxy” just for laughs.
    But then, I -AM- a bum…

  8. Jon Hanford

    @#6 dcsohl,

    The unusual radio transient in M82 is most likely a rare, exotic binary microquasar, similar to SS 433 in our own galaxy and S 26 in NGC 7793. The observed superluminal motion would be from a *subluminal* jet expelled from the system. A paper describing radio and x-ray observations of this object can be found here:

  9. Wzrd1

    I look at the galaxy and consider dispersion of gasses.
    As in the apparent gap created by galactic core jets that have begun to fill in.
    And considering the amount of NOT cleared areas near the jet region, considering the high end probability of new jets forming, as in forming REAL soon.
    As was said, new galaxy, energetic events, in short, things move far more quickly than in our middle aged galactic environment.
    Honestly, I’d keep a part of one eye on that galaxy, JUST to be impressed when it DOES go active. I’ll be sooner, not later.
    That said, I’m thinking of stellar terms (not galactic), not Earth year terms.


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