Author Topic: Hubble: Spirals  (Read 94375 times)

c_cld

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Re: Hubble: Spirals
« Reply #30 on: May 06, 2010, 09:07:18 am »
Nice spiral in tile 14 of GEMS field, waiting a close look-up in Hubble zoo

Oozyzoozy

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Re: Hubble: Spirals
« Reply #31 on: May 06, 2010, 09:57:06 am »

50003033

Oozyzoozy

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Re: Hubble: Spirals
« Reply #32 on: May 06, 2010, 09:59:18 am »

14008000

Oozyzoozy

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Re: Hubble: Spirals
« Reply #33 on: May 06, 2010, 10:01:48 am »

50011803

elizabeth

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Re: Hubble: Spirals
« Reply #34 on: May 06, 2010, 04:07:03 pm »
13043039

paulrogers

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Re: Hubble: Spirals
« Reply #35 on: May 06, 2010, 04:33:52 pm »
Beautiful indeed. As a lay person (not even an amateur astronomer) simple questions abound. How do some galaxies get so many spiral arms from just two jets at the nucleus?  Do the jets pulse?

I'm not an astronomer either.  I'm not sure, but I don't think every spiral galaxy has, or has had, "jets", the sort produced by massive black holes "chowing down".  Those seem to be axial, out of plane, anyway.  It's not obvious to me how that would influence the development of arms.

I've always believed that spirals are produced by off-center, oblique collisions of even lenticular galaxies. With respect to one of them, the other comes in at some random angle and off-center, ahead or behind this galaxy.  The "glancing blow" imparts an angular momentum among them.  Think of a couple very unsteady skaters approaching each other at an angle and off-center, grasping for each other as a 2-D example.  Their momentum would tend to swing them around each other. In the case of galaxies in 3 dimensions, it's easy to see how they get spinning, but not obvious how this imparted angular momentum leads to the development of arms either.  Let us know what you discover. :)

Shortly after posting that, I got this:

http://zoo-hst.s3.amazonaws.com/90033427.jpg
It looks like a one-armed spiral, i.e. a smaller galaxy approached the central lenticular one on the left side, and is being wrapped around it gravitationally.  As those stars move around the central mass, they'll begin to drag the formerly stationary stars around with them.  Eventually the whole thing will have an angular momentum.
« Last Edit: May 06, 2010, 04:58:36 pm by paulrogers »

elizabeth

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Re: Hubble: Spirals
« Reply #36 on: May 06, 2010, 04:46:43 pm »
12024931

elizabeth

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Re: Hubble: Spirals
« Reply #37 on: May 06, 2010, 06:53:07 pm »
13043000

JeanTate

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Re: Hubble: Spirals
« Reply #38 on: May 06, 2010, 10:27:58 pm »

90018353 - particularly bright nucleus


13049884 - maybe an inner ring?

elizabeth

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Re: Hubble: Spirals
« Reply #39 on: May 06, 2010, 10:30:25 pm »
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Oozyzoozy

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Re: Hubble: Spirals
« Reply #40 on: May 07, 2010, 01:15:02 am »

I'm not an astronomer either.  I'm not sure, but I don't think every spiral galaxy has, or has had, "jets", the sort produced by massive black holes "chowing down".  Those seem to be axial, out of plane, anyway.  It's not obvious to me how that would influence the development of arms.

I've always believed that spirals are produced by off-center, oblique collisions of even lenticular galaxies. With respect to one of them, the other comes in at some random angle and off-center, ahead or behind this galaxy.  The "glancing blow" imparts an angular momentum among them.  Think of a couple very unsteady skaters approaching each other at an angle and off-center, grasping for each other as a 2-D example.  Their momentum would tend to swing them around each other. In the case of galaxies in 3 dimensions, it's easy to see how they get spinning, but not obvious how this imparted angular momentum leads to the development of arms either.  Let us know what you discover. :)


Thank you for your thought provoking response Paul.  Made me think over why I believed spirals come from jets.  I certainly wasn't trying to describe 'every spiral galaxy' there are obviously very many different processes going on.  As a real Newbie I'm quite happy to discard any incorrect beliefs but need a bit more info to convince me that the material for [at least some] spiral arms doesn't originate from jets emanating from the nucleus.   

I went searching for galaxies that support my thinking.  There is one in this thread which I will attach later but most Hubble spirals are fuzzy in the center.  I haven't had a chance to look at all the hundreds of spirals in the SDSS threads but here is a simple two spiral example:

Posted by: KARHU  August 23, 2007

http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=138.77&dec=41.99695

It would seem to me fairly clear that the material for the two arms originates from the central bar ends (jets?)  By all means have collisions and gravitational bypasses later to set the galaxy spinning but the source of the arms is surely from the central jets(?)   Now, if the jets continued to emit material and there were collisions, or bypasses then that might create more arms?   

There is also this beautiful SDSS Galaxy:

Posted by tiger-t on August 17, 2007

http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=190.30536014&dec=10.15566215

Could this be a 'virgin' galaxy before any collisions or gravitational bypasses have set  it spinning?

This discussion has probably occurred many times previously in other threads that I haven't read (yet)
and although I'm a grandfather I don't want to appear to be 'teaching grandma to suck eggs'...  but I really would appreciate more help and ideas to set me on the right track.

Here is the simple galaxy in this thread that also seems to support the jets-spirals connection:

Posted by Marcus2 on May 05, 2010

50007563

Phew, hope all that works out. If not I'll rework it  ;D

Anaclaudia

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Re: Hubble: Spirals
« Reply #41 on: May 07, 2010, 02:56:08 am »


90034717

Marcus2

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Re: Hubble: Spirals
« Reply #42 on: May 07, 2010, 03:37:21 am »
10010879


Marcus2

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Re: Hubble: Spirals
« Reply #44 on: May 07, 2010, 03:55:36 am »
50005217