Spiral galaxies

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malcm
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Re: Spiral galaxies

Post by malcm » Mon Aug 24, 2009 1:36 am

John: Here's a late answer to your June comment - if you're still checking: While spirals are numerous, galaxies come in various shapes - many ellipticals as well as others written about by Halton Arp in his books, Atlas of Peculiar Galaxies and another, Quasars, Redshifts and Controversies. Check also the book Galaxies by Tim Ferris.

harry
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Re: Spiral galaxies

Post by harry » Mon Aug 24, 2009 6:41 am

G'day from the land of ozzzzz

Chris said
Galaxies are not the product of any kind of explosion. They were formed when material came together by gravitational attraction. When that happens, conservation of angular momentum tends to result in motion on a plane. It's why galaxies are disc shaped, as well as why planets orbit stars on a plane.
How do you explain the evolution of galaxies and their form as per the Hubble Tuning fork.

How do you explain the cartwheel galaxies?
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Qev
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Re: Spiral galaxies

Post by Qev » Mon Aug 24, 2009 12:24 pm

The 'Hubble Tuning Fork' is a classification system, it doesn't actually have anything to do with galactic evolution.
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Chris Peterson
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Re: Spiral galaxies

Post by Chris Peterson » Mon Aug 24, 2009 1:49 pm

harry wrote:How do you explain the evolution of galaxies and their form as per the Hubble Tuning fork.
The shape a galaxy has depends on its initial mass, age, and history of interaction with other galaxies. The Hubble classification tells us nothing about evolution, only about form. Elliptical galaxies are probably the most evolved, forming after multiple collisions and matter absorption events.
How do you explain the cartwheel galaxies?
Is there more than one? Like most galaxies with odd form, the Cartwheel formed from a galactic collision.
Chris

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bystander
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Re: Spiral galaxies

Post by bystander » Mon Aug 24, 2009 2:39 pm