Skip to main content Accessibility help
×
Home
Hostname: page-component-684899dbb8-x64cq Total loading time: 0.816 Render date: 2022-05-19T06:45:01.210Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "useRatesEcommerce": false, "useNewApi": true }

RING GALAXIES

Published online by Cambridge University Press:  05 September 2017

Get access

Summary

Galaxies come in a wide range of forms. Among these are some especially beautiful examples with prominent ring structures. These galactic exceptions have varied causes.

THE MORPHOLOGY OF RING GALAXIES

Like the irregular and interacting galaxies, ring galaxies are galactic exceptions whose history has played a deciding role. They are the result of collisions of two galaxies which led to something new – a ring galaxy. In addition to a bright nucleus, this type of galaxy has a ring, which is usually symmetrically oriented about the centre. The size of the ring greatly exceeds the size of the central component. This ring is very prominent in photos since it contains bright starforming regions with young, massive stars. One usually recognizes a blue ring which contrasts in colour with the yellowish central component. The colours of these components remind one of a spiral galaxy with its bulge and the spiral arms, thus a ring is comparable to a closed spiral arm. This morphological peculiarity was explicitly taken into account by de Vaucouleurs in his classification scheme: “(R)” is placed at the beginning of the description when a ring is seen. When the morphology of the ring is observed in more detail, differences from galaxy to galaxy become apparent. One thus distinguishes two cases: a) the ring formed via a genuine collision of two partner galaxies, b) the ring structure is the result of wound-up tidal tails of two mutually orbiting partner galaxies.

In the latter case, perspective also plays an important role, since tidal tails result in a sufficiently bright ring only when seen one on top of the other. Ring galaxies formed by a collision are often referred to in the literature as “true colliding galaxies”. But in this case as well, a small angle between the plane of the ring and the line of sight can mean that one doesn't recognize the ring, since it is covered by dust regions or parts of the spiral arm. It is assumed that only about 30 per cent of all ring galaxies can be reliably identified.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 2017

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×