Author Topic: Saturday 17 March 2012 An enigma wrapped in a riddle (surrounded by emptiness?)  (Read 15114 times)

Lovethetropics

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Hello dear fellow zooites, long time no OOTD  ;D  Thanks to our wonderful moderator Jean, Budgieye, and Blackprojects for their contributions.  Love you guys!
As usual with GZ and me this galaxy  just presented itself the same day dear Jean sent me a message asking for an OOTD.
Kalali asked on the newbie's thread:
Quote from: Kalali
Hi, this is the first time I come on the forum.
I found this object a while ago and I was wondering if it was anything special?



This is the object.  Budgieye answered that it had been posted before by 3 zooites, Hrundi, Bruno and mercurtin.

Quote from: Budgieye
Hi Kalali
Welcome to the Galaxy Zoo forum  :)

What a fascinating galaxy.

 It is an SDSS image, so I found that it has been posted before.

by Hrundi, who thought that it might be a polar ring galaxy
http://www.galaxyzooforum.org/index.php?topic=277602.msg506361#msg506361

by Bruno who decided to place it in Ringed and Pseudoringed Galaxies   
http://www.galaxyzooforum.org/index.php?topic=10635.msg376103#msg376103

and mercurtin who decided it was a ring galaxy
http://www.galaxyzooforum.org/index.php?topic=277602.msg506361#msg506361

Ringed galaxies were thought to be rare, until Zooites started finding lots of them.
It is not a ring galaxy, because it has a centre.
It is hard to see what is actually happening, whether it is a spiral galaxy with ring around it, or an elliptical with a polar ring caused by a collision.

It may be an interesting example of a ringed galaxy that is just forming after a collision with another galaxy, and the ring has not completely formed.
I would like to hear is someone has a different opinion.

That's when I saw the galaxy in question so of course I answered:
Quote
Hi Budgieye, let's ask Jean Tate or one of the zookeepers.  The center galaxy and the ring are so different...like they come from different places  ???

Let's see if it shows inverted now...


Blackprojects posted the spectrum:
Quote
That looks like a familiar Signature


So it has also a quasar?  Begs to be an OOTD  ;D

And then Jean Tate, our beloved OOTD moderator and I had quite a conversation, by email. Here are some highlights:

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Jean: I think it'd be a terrific object for an OOTD, if for no other reason than its odd shape (are they arms? a ring/two rings? some sort of shells? tidal tail merger remnants?). Personally, I don't recall seeing any galaxy that looked quite like that (can you?)!  :o  8)

So, what are you waiting for!  ;D

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Me: Jean you're too much!  Ok, let's tumble some thoughts around...this is what you have to say about it:

Quote from: JeanTate
This is SDSS J233125.71-002759.0, DR7 ObjId 587731185663934633. It is also a 2MASX object, 2MASX J23312572-0027588. According to NED, the only published paper which covers this galaxy is "Observing the dark matter density profile of isolated galaxies", arXiv:astro-ph/0301360v1. To my untrained eye, the spectrum looks, at first glance, to be quite normal; however, on closer inspection, there do seem to be some oddities! For example, the [NII] nebular lines look quite strong, but the other 'usual suspects' nebular lines - [OIII], [OII], [SII] - are wimpy to non-existent.  So, yes, Lovethetropics, this galaxy is certainly begging to be an OOTD!

The only paper covers the galaxy because of being isolated.  Here comes the question, what in God's name is this odd galaxy doing in isolation?  what happened to it?  Could it be that very long ago this galaxy had an encounter with another galaxy and those are the remnants of the collision?

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Jean: These are, of course, all very good questions!  :D

Is its unusual morphology (have I been around here for long enough now that I start using 'morphology' rather than 'shape'?!  :o ) somehow due to its isolation? Was it, perhaps, the result of a collision between two otherwise quite isolated galaxies? I don't know (but I wonder what the environment looks like, when you zoom out).

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Me: But the ring (or whatever it is) is blue while the galaxy is gold reddish and looks like a very tight spiral or (heaven help us) an elliptical...can't be lenses, right?  too weird even for lenses.

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Jean: Yes, I think that, no matter how weird it is, it won't turn out to be lensed (though I'd *love* to have to eat those words!)

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Me: A momentous clash would leave both galaxies in shambles but this is not the case...the big one is very serene while the "pseudo-ring(s) are still producing stars...
Could it be that the color of the ring or whatever is not real?  There's nothing else on the vicinity that would explain the blue-purplish ring or maybe I am missing something?
You must have seen more galaxies than me but I can't recall any like this one, or even what to call it:  ringed, ring, pseudo-ring, a new kind of galaxy?

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Jean: I think it's unusual, and, like you, can't think what to call it (and I'd be not the least bit surprised to learn that you've actually seen more galaxies than me). But that's what makes it such a great OOTD, right? We should get more eyes on it ... (note to self: check out what the votes were, in Table 2 of the GZ DR1 paper).

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Me: Overlapping galaxies that have nothing to do with one another?  That last one is my wishbone talking, I don't believe in that kind of coincidence, at least not yet.  ;D
If you have a flash of inspiration it would be greatly appreciated.  Or an opinion to my ramblings, at least you're a professional astronomist, I am just a housewife who never finished college and I was studying to be a LAWYER ???

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Jean: Well, here's the thing: it's unusual, and visually striking, so it'd make a great OOTD, no matter what it turns out to be!  ;D

By the way, I wrote two OOTDs on isolated galaxies: LOGs, Waveney, and dark halos, and Galaxies, type -3 to 10. In my research for those, I did not come across anything like this!
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[/quote]

So dear readers, what do you think this galaxy is?  Feedback will be greatly appreciated and thanks for reading this OOTD  ;D
« Last Edit: March 17, 2012, 01:54:37 pm by Lovethetropics »

 *and find lots of asteroids  ;D

c_cld

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This galaxy seen in DR7 and in DR8 side by side
5877311856639346331237666407365542124

Hint of a  ring in DR7 seems fainter in DR8, and in south appears a more delimited blob. It was not confirmed as a satellite in catalog
J/ApJ/598/260/table3 Satellites orbiting isolated galaxies

So it seems to be a normal SO / Sa galaxy  ???

AlexandredOr

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Very interesting. Thank you Aida  :D

Baby star opening its eyes on the Universe.

elizabeth

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 :D :D Maybe a Polar Ring?  8) OOTD

jules

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OK - I'm more of a Sun and Moon girl these days but this has me intrigued. At first glance it appears to be on its way to becoming a ringed galaxy - but it's clearly not as simple as that! Thanks for highlighting this Aida.

Lovethetropics

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Thanks Claude, Alexandre, Liz and Jules  ;D ;D ;D :-* :-* :-* :-* :-*

 *and find lots of asteroids  ;D

Tsering

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Nice OotD!
Om Tare Tuttare Ture Soha

joinpep

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L,

587731185134338213 BBS thread, AHZ6000ctw
587731185663934633 OOTD Sy2
http://www.galaxyzoo.org/examine/AHZ2001p4c

19032012 update
It's dangerous to presume what systems can or can't do.
They are not 'isolated' by cosmological standards.
(Try the null hypothesis - what doesn't come from without may come from within.)
« Last Edit: March 19, 2012, 10:22:09 am by joinpep »

Lovethetropics

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Thank you Join, don't you think those galaxies are surrounded by other galaxies that could have made a close pass or even some kind of merger but the one on the OOTD is alone with no visible culprit.  :D

See?  There's nothing close enough to produce that starforming ring:

« Last Edit: March 19, 2012, 01:53:36 am by Lovethetropics »

 *and find lots of asteroids  ;D

Mukund Vedapudi

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Nice  :) :)
Faith is the bird singing when the dawn is yet dark.

Lovethetropics

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Thanks Mukund  ;D :-* :-* :-*

 *and find lots of asteroids  ;D

JeanTate

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That is from an earlier OOTD, called the Celtic Knot.

What I see as being in common between these two galaxies is this: there are "arms" which do not have a co-planar, spiral shape, centered on the galactic nucleus.

We have all seen (spiral) galaxies with odd-looking arms; however, other than in merging systems, polar ring galaxies, or lenses/lensed background galaxies, how many such arms have you seen which are not, in some sense, spiral [1]?

Ring, and ringed, galaxies are an exception; however, by definition, the (ring) arms are a fixed distance from the nucleus (once projection is taken into account) [2].

In both the OOTD galaxy and the "Celtic knot", it's very hard to see how the two (OOTD galaxy) and 10-o'clock arm cf the other arms (Celtic knot galaxy) could possibly be co-planar.

Here's the spectrum of the Celtic knot galaxy:



The [OIII] lines are faint, H-alpha is in emission, and [NII] is strong. That's pretty much the end of the similarities, with respect to emission lines: for this galaxy, [SII] is strong, H-beta is in emission, and there's certainly [OII] emission.

Has anyone come across a galaxy with arms which are not co-planar, other than one's that are obviously in a merging system, polar ring galaxies, or lenses/lensed background galaxies?

And what about the spectrum? Has anyone seen a galaxy spectrum with strong [NII] lines but faint-to-non-existent [OIII], [SII], and [OII] lines (irrespective of what the Balmer lines are)?

[1] the galaxy joinpep posted seems to have a ring, and a single, prominent, spiral arm.
[2] For sure, some rings may be somewhat elliptical, even when de-projected.

Lovethetropics

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YES!  You are right Jean, we still have a mystery to solve!  8) ???

 *and find lots of asteroids  ;D

zutopian

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Here are Hubble images of spirals with strange arms:


http://www.galaxyzoo.org/examine/AHZ30001ku                              http://www.galaxyzoo.org/examine/AHZ2001gkr 

Lovethetropics

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Way to go zutopian!  Thank you so much!  ;D ;D ;D

 *and find lots of asteroids  ;D