A weird and lovely spiral for your weird and lovely Monday

By Phil Plait | April 2, 2012 10:42 am

I just got back from a week of travel, and I’m facing down a hundred emails, tons of news, about a billion things to write about, and then more travel later this week.

So when I see the folks at Hubble have posted a picture of a weird, pretty spiral, I figure it makes my job easier. I can just post a cool picture! So here it is:

[Click to galactinate.]

But dagnappit, I can’t leave it at that. I never can.

This is NGC 4980, a spiral about 65 million light years away or so. Most spirals have well-defined arms, but this one is just… odd. The arms are indistinct, and also fairly asymmetric. If I had to guess I’d say it recently suffered a collision with another galaxy, but apparently there are no other galaxies near it! I was rather surprised to find that there isn’t much in the professional literature about it; it’s close and bright, and worthy of some study.

The arms of the galaxy are there, and appear blue from the combined light of billions of young, massive, hot stars. As with many spirals, there are older, redder stars in the center; those are in the arms as well, but outshone by the brighter blue stars. Usually, the cores of spiral galaxies long ago ceased making stars, so all the big blue ones have long-since exploded, leaving behind the cooler, redder stars.

Note that the very core of the galaxy is a pin-point source of light. I saw on some websites that NGC 4980 is an emission line galaxy — it emits light at very specific colors, like a neon sign — which is a clear indication that a supermassive black hole is gobbling down matter there in the galaxy’s heart. As matter swirls in, it forms hot, flat disk (too small to see here) that is incredibly bright. This lights up clouds of nearby gas, which respond by glowing at those narrow slices of color. There aren’t too many of these "active galaxies" near us on a cosmic scale, so again I’m rather surprised this hasn’t been studied more!

So there you go. A lovely spiral to start your week, and one that’s also a little bit on the odd side. Frankly, lovely and odd is how most of my weeks start, so I’m happy to share.

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (11)

  1. Too bad it’s awfully dim for most amateur scopes at magnitude 15 and over 2 arc minutes across (and a good ways south making it harder for us northerners to see well anyway), but that is definitely some interesting info about that galaxy. Thanks for posting about it, Phil.

  2. Tara Li

    Is it a spiral making the transition to an elliptical, or maybe vice-versa?

  3. Jeff

    thanks, I love this emission line galaxy, relates to the experiments the students have done for years with hi-volt tube and low pressure gases like H, He, Ne, etc., and a simple diffraction grating separates the lines; they are very narrow at specific colors. It is amazing that all round the universe, these same lines exist as those right down in the lab.

  4. VinceRN

    What I want to know, is how did our host know my Monday would be so weird?

  5. Not sure i’d call this a spiral. It’s got hot blue stars everywhere and in random structures.
    Could it be dust and gas obscuring the structure?

  6. Aaron

    “I’m rather surprised this hasn’t been studied more!” — With all the millions of galaxies that distance or nearer, maybe they just haven’t gotten around to it yet.

  7. Wzrd1

    It seems to be a galaxy that HAS “eaten” another galaxy, perhaps during a final orbital merge from quite some time ago.
    I seem to recall seeing models for our own galaxy’s final mergers with the dwarf galaxies that are to eventually pass through, orbit back, pass through and eventually merge.
    A decent survey in that galactic neighborhood should show some ejected stars, which would give a time for the merger, if that is the case.

  8. Messier Tidy Upper

    Great photo, interesting galaxy thanks BA. :-)

    Our own Milky Way has, perhaps, fairly indistinct spiral arms too. (Its a bit hard to tell from inside as the latest ‘New Scientist’ magazine notes with different studies producing different “maps” of the Milky Way’s structure. There are certainly large dark rifts, nebulous regions – such as the recently discussed Dragonfish nebula – and clouds and unclear separations and connections with our Galaxy’s arms so, yeah, we could have a messy look as seen from intergalactic space too.)

    Hmm .. perhaps from outside our Galaxy and this look similar(~ish?) ?

  9. Maybe the colliding neighbor is hiding BEHIND it? Danged coward if you ask me.

  10. I just think it is beautiful.

  11. Chris A.

    @Aaron (#6):

    “‘I’m rather surprised this hasn’t been studied more!’ — With all the millions of galaxies that distance or nearer, maybe they just haven’t gotten around to it yet.”

    Actually, at that distance (just a bit further than the Virgo Cluster), I’d estimate that the number of galaxies to study is more like tens of thousands, not millions. That’s based on the fact that the Virgo Cluster is, by far, the largest collection of galaxies within 60 million light years, and it’s estimated to have “only” around 2000 galaxies in it.


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