Do Bars Kill Spiral Galaxies?

This morning a press release went out from the Royal Astronomical Society about the Galaxy Zoo 2 paper I have previously blogged about (post about submission, arXiV link, post about acceptance).This paper on the trends of the fraction of disk galaxies which have bars is currently in press at Monthly Notices.

If you recall, our main finding was that redder disk galaxies are significantly more likely to host a bar than bluer disk galaxies, with the red spirals being the extreme of that population (very red disk galaxies, almost all of which seem to host bars).

NGC 1300 - a classic barred spiral - as seen by HST.

NGC 1300 - a classic barred spiral - as seen by HST.

So we speculate that the bar might somehow be involved with the process which turns the disk galaxies red – and the press release has gone our with the title “Bars Kill Spiral Galaxies”.

Of course it might not be quite that simple – it’s possible that the increased likelihood of having a bar is actually a side effect of the disk being red, or even that both phenomena (the disk turning red, and getting bar) are coming from some third process to do with the environment the galaxies live in. My best guess is that it’s some combination of all those factors working together – but of course we don’t do science on “best guesses” so lots more work is happening using the sample of bar classifications you gave us in Galaxy Zoo 2. We’re studying the fraction as a function of local environment, I’ve already mentioned here the results which came from the Bar Drawing site which are very exciting (more on that soon), and I’m also working on combining your classifications with information on the gas content (the fuel for future star formation) from the ALFALFA survey (which uses Arecibo – a very cool telescope).

I think what’s very interesting is all this could have an impact on the future fate of our own Galaxy which is known to host a bar.

So that’s lots of exciting science coming soon, and thanks again for all those clicks!

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About karenlmasters

Astronomer at Institute of Cosmology and Gravitation, University of Portsmouth. Project Scientist for Galaxy Zoo. Spokesperson for the Sloan Digital Sky Survey. Busy having fun with astronomy!

6 responses to “Do Bars Kill Spiral Galaxies?”

  1. Gwydion Williams says :

    Another nice result. I have added it to the Wikipedia entry for Galaxy Zoo

  2. José Campos says :

    I wonder what is the ratio between gas and the INTERSTELLAR DUST within the arms and the bars of this type of galaxy? Could it be that a huge proportion of dust makes them look redder?

  3. Karen Masters says :

    Jose,
    We showed pretty conclusively in the passive red spiral paper that they are not just red due to dust reddening. Some disks are, but not all of them.

    Karen.

  4. Virgil Fritz says :

    Dear Ms. Masters:

    I’ve looked at barred spiral galaxies and non-barred spirals for some time. I’m a biologist but my heart belongs to Astrophysics. From the start it seemed obvious to me that the bar is caused by black holes at either end. Perhaps they ‘spin off’ of the central massive black hole as it perturbs dust and stars, like eddies in a stream. As the bar spins with the galaxy the dust and stars are scooped in by the bar and funneled towards the black holes both central and opposing. Thus they would increase the rate of dust and gas, the building blocks of new stars, being consumed and thus shortening the life of star formation, the life blood of spiral galaxies. It’s just what I’ve thought over the years, I hope it gives you some inspiration and ideas. Thank you very much, sincerely, Virgil Fritz, AllnightVi@aol.com

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