Featured Research

from universities, journals, and other organizations

New theory of evolution for spiral galaxy arms

Date:
April 25, 2011
Source:
Royal Astronomical Society (RAS)
Summary:
A study of spiral patterns found in galaxies like our Milky Way could overturn the theory of how the spiral arm features form and evolve. Since 1960s, the most widely accepted explanation has been that the spiral arm features move like a Mexican wave in a crowd, passing through a population of stars that then return to their original position. Computer simulations now suggest that the stars actually rotate with the arms.

Snapshots of face-on view of a simulated disc galaxy. A Brighter colour indicates higher density. The Image shows two examples of star particles: the red star are travelling at the leading side of the arm, and the blue star are at the trailing side. It can be seen that the blue and red stars interchange their radial distances, with rapid migration within 40 million years. The dotted lines trace circles with radii of 4, 5 and 6 000 parsecs (1 parsec = 31 trillion kilometres), to guide the eye.
Credit: R Grand/MSSL/UCL

A study of spiral patterns found in galaxies like our Milky Way could overturn the theory of how the spiral arm features form and evolve.

The results were presented by postgraduate student, Robert Grand, at the Royal Astronomical Society's National Astronomy Meeting in Llandudno, Wales.

Since 1960s, the most widely accepted explanation has been that the spiral arm features move like a Mexican wave in a crowd, passing through a population of stars that then return to their original position. Instead, computer simulations run by Grand and his colleagues at University College London's Mullard Space Science Laboratory (MSSL) suggest that the stars actually rotate with the arms. In addition, rather than being permanent features the arms are transient, breaking up and new arms forming over a period of about 80-100 million years.

"We have found it impossible to reproduce the traditional theory, but stars move with the spiral pattern in our simulations at the same speed. We simulated the evolution of spiral arms for a galaxy with five million stars over a period of 6 billion years. We found that stars are able to migrate much more efficiently than anyone previously thought. The stars are trapped and move along the arm by their gravitational influence, but we think that eventually the arm breaks up due to the shear forces," said Grand.

In the simulations, Grand found that some stars gradually move outwards and inwards along the spiral arms. Stars traveling at the leading side of the spiral arm slide in towards the center of the disc, whereas the stars traveling at the trailing side are kicked out to the edges.

"This research has many potential implications for future observational astronomy, like the European Space Agency's next corner stone mission, Gaia, which MSSL is also heavily involved in. As well as helping us understand the evolution of our own galaxy, it may have applications for regions of star formation," said Grand.


Story Source:

The above story is based on materials provided by Royal Astronomical Society (RAS). Note: Materials may be edited for content and length.


Cite This Page:

Royal Astronomical Society (RAS). "New theory of evolution for spiral galaxy arms." ScienceDaily. ScienceDaily, 25 April 2011. <www.sciencedaily.com/releases/2011/04/110420111343.htm>.
Royal Astronomical Society (RAS). (2011, April 25). New theory of evolution for spiral galaxy arms. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2011/04/110420111343.htm
Royal Astronomical Society (RAS). "New theory of evolution for spiral galaxy arms." ScienceDaily. www.sciencedaily.com/releases/2011/04/110420111343.htm (accessed April 24, 2014).

Share This



More Space & Time News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nuclear-Level Asteroids Might Be More Common Than We Realize

Nuclear-Level Asteroids Might Be More Common Than We Realize

Newsy (Apr. 23, 2014) The B612 Foundation says asteroids strike Earth much more often than previously thought, and are hoping to build an early warning system. Video provided by Newsy
Powered by NewsLook.com
NASA Chief Outlines Plan for Human Mission to Mars

NASA Chief Outlines Plan for Human Mission to Mars

AFP (Apr. 22, 2014) NASA administrator Charles Bolden, speaking at the 'Human to Mars Summit' in Washington, says that learning more about the Red Planet can help answer the 'fundamental question' of 'life beyond Earth'. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Nasa Gives You An Excuse to Post a Selfie on Earth Day

Nasa Gives You An Excuse to Post a Selfie on Earth Day

TheStreet (Apr. 22, 2014) NASA is inviting all social media users to take a selfie of themselves alongside nature and to post it to Twitter, Facebook, Flickr, Instagram, or Google Plus with the hashtag #globalselfie. NASA's goal is to crowd-source a collection of snapshots of the earth, ground-up, that will be used to create one "unique mosaic of the Blue Marble." This image will be available to all in May. Since this is probably one of the few times posting a selfie to Twitter won't be embarrassing, we suggest you give it a go for a good cause. Video provided by TheStreet
Powered by NewsLook.com
SpaceX's Dragon Spacecraft Captured by International Space Station

SpaceX's Dragon Spacecraft Captured by International Space Station

Reuters - US Online Video (Apr. 20, 2014) SpaceX's unmanned Dragon spacecraft makes a scheduled Easter Sunday rendezvous with the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins