Coincidental spirals for your Monday pleasure

By Phil Plait | October 24, 2011 9:59 am

It’s been a while since I’ve done a Monday spiral, so here’s a great example of one: the nearby beauty M96.

[Click to oooh-and-ahhhhhenate.]

There’s some nifty stuff here. M96 is about 36 million light years away — relatively close by, for a big galaxy — and is part of a small group of galaxies called (can you guess?) the M96 Group. This is a small collection of a dozen or so galaxies, much like the small group of galaxies to which we belong, called (can you guess that one?) the Local Group. M96 is about the same size as our galaxy, too: roughly 100,000 light years across.

The spiral shape is not as symmetric as usually seen in these types of galaxies, and that’s almost certainly due to gravitational interactions with the other galaxies in the group (which are spread out enough not to be seen in this close-up). You can see lots of dark dust swirling around the center of the galaxy, blocking the light from stars behind it. You can see more on the right than on the left, indicating the right side of this galaxy is the side of the galaxy nearer to us. But that top looping arm is way out of proportion to the other side of the galaxy, so it’s probably been tugged out due to the other galaxies in the group. You can see clumpy regions of blue along its length; that’s where stars are being born, blasting out lots of ultraviolet light and causing the surrounding gas to glow.

I think my favorite part of this picture, though, is the reddish edge-on spiral galaxy located in the upper left, almost perfectly aligned with the spiral arm of M96! This is certainly a coincidence; the edge-on galaxy is probably much farther away. The red tinge to it supports that idea; dust in the arm of M96 would absorb bluer light from the more distant galaxy, letting the red light through.

Measuring its size off my screen, I get that it’s about 1/5th the length of M96. If it’s the same size physically as M96, then it’s probably 5 or so times farther away, maybe 150 – 200 million light years off. That’s actually a pretty good distance away. Yet in this image details can still be seen; that’s the advantage of using the colossal 8-meter mirror on the Very Large Telescope! You can still get a pretty clear picture of fantastically distant objects, even when they’re partially obscured by foreground objects.

And you get a gorgeous picture out of it, too.

Image credit: ESO/Oleg Maliy

Related posts:

The dusty depths of a spectacular spiral galaxy
The Triangulum Galaxy, writ large
A Swiftly UV galaxy
M83’s nursing arms

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (15)

  1. Chris
  2. OtherRob

    What Chris said. :)

  3. Infinite123Lifer

    Is there such a thing as coincidence? (especially in spirals)

    I think existence itself suggests some type of order (our theories support that; math). Does chance have a reality? After the fact; I think, quite not.

    What about Mondays? Pleasurable? Really? Jk

    Two oxymorons in one title. Coincidence??? o_O

    Splendid! :-)

    Can you count the total # of galaxies in this awesome universal jellybean jar?

  5. Robin Byron

    I can look at galaxies all day and I have, at Galaxy Zoo. They are so beautiful and cause the mind to speculate on the most outlandish(?) thoughts.

    Question, Phil. Around a year ago the Harvard-Smithsonian Center for Astrophysics said they had good evidence that the Milky Way is actually about the same size as Andromeda (~150kly). Has that been poo-pooed?

  6. chris j.

    spiral? that inner ring looks pretty darn ring-like to me. and the irregular outer arms seem consistent with transitory arcs seen around ring galaxies as artifacts of the interaction with the other (unseen here) galaxy.

  7. Stargazer
  8. Remember when NASA unveiled “The Mice”, one of the first pix from the new Hubble ACS

    One of my colleagues said, “Nice picture, except for those big spirals in the way…” No surprise, he’s a cosmologist!

  9. Chris A.

    Kudos to ESO–My initial assumption was that it was a Hubble shot.

  10. siravan

    The reddish edge-on galaxy is 2MFGC 08391 (also called 2MASX J10465229+1150201).

  11. Jon Hanford

    M 96 has been implicated in the formation of the Leo Ring, a huge annulus of cold hydrogen gas found nearby:

    An accompanying video shows the proposed head-on collision of M 96 with another galaxy, NGC 3384, that may have occurred over a billion years ago:

  12. bk_2

    It looks to me as though the outer ring is on different plane to the inner spiral. The top is above the spiral plane, the bottom of it below. It is roughly in a plane which is tilted twenty odd degrees to the spiral’s plane. But maybe it’s just an artifact of the geometry of the outer irregular arcs.

  13. jennyxyzzy

    Hmmm, I was surprised when Phil explained that this photo was taken by an earth-bound telescope, so I went scuttling off to the VLT’s webpage, where I found this little nugget on the front page:

    “With this kind of precision the VLTI can reconstruct images with an angular resolution of milliarcseconds, equivalent to distinguishing the two headlights of a car at the distance of the Moon.”

    Wouldn’t that mean that the VLT is capable of seeing the moon landers/rovers? I thought we could only do that from the spacecraft that are orbiting the Moon???

  14. Ian Straton

    @ 13,
    In theory I suppose it would, however pointing an 8m mirror at the moon would fry the ccd on the recieving end so there would be no way to take a picture… putting your eye to it probably wouldn’t be a great idea either…

  15. Messier Tidy Upper

    Wow! Splendidly magnificent indeed. :-)

    Thanks BA – for this new desktop background & a great write up too. :-)

    Mind you I’m surprised you didn’t save this for easter, with the easter-egg nestled inside an easter egg appearance of Messier 96 here. Surprised but not unhappy! Course easter is a lo-oong time away yet. ūüėČ

    @ 13. jennyxyzzy : I think our Moon would be a wee bit too bright for the VLT to look at it – same as it is with the Hubble space observatory.

    @11. Jon Hanford : Thanks. Cheers to (#10.) siravan & (#8) Peter (@polarisdotca) for their contrubutions here too. :-)

    @ 9. Chris A. : “Kudos to ESO ‚Äď My initial assumption was that it was a Hubble shot.”

    Yep, mine too. ūüėČ



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