Featured Research

from universities, journals, and other organizations

Most elliptical galaxies are 'like spirals'

Date:
July 15, 2011
Source:
University of Oxford
Summary:
The majority of 'elliptical' galaxies are not spherical but disc-shaped, resembling spiral galaxies such as our own Milky Way with the gas and dust removed, new observations suggest.

Maps of the observed velocity of the stars in the Atlas3D survey. Red/blue colours indicate stars moving away/towards us respectively. Fast rotating and disk-like galaxies are characterised by two large and symmetric red/blue peaks at the two sides of the centre and constitute the vast majority of the sample.
Credit: OU/Cappellari

The majority of 'elliptical' galaxies are not spherical but disc-shaped, resembling spiral galaxies such as our own Milky Way with the gas and dust removed, new observations suggest.

Related Articles


The results come from Atlas3D, a survey of all 260 early-type ('elliptical' and 'lenticular') galaxies in a well-defined volume of the nearby universe. Atlas3D shows a much closer link between 'elliptical' galaxies and spiral galaxies than previously thought. The findings are likely to change our ideas of how galaxies form and see astronomy text-books rewritten.

A report of the research, by the international Atlas3D team, is published in an upcoming issue of Monthly Notices of the Royal Astronomical Society.

'Because we rely on optical images, up until now it has been very difficult to separate discs of stars seen face-on from rounder, spherical balls of stars seen edge-on,' said Dr Michele Cappellari of Oxford University, a Royal Society Research Fellow who is the UK lead of the Atlas3D project. 'But because stars in a thin disc rotate much faster than those in a spheroid, obtaining maps of stellar motions for all elliptical galaxies in the sample, we have shown that out of these 66% are disc-like.'

The findings suggest that the idea that galaxies can be clearly separated into two different 'families', spiral galaxies and elliptical galaxies, reflecting two distinct paths to galaxy formation, is inaccurate.

This 'two families' approach was famously visualised in Edwin Hubble's 'tuning fork' diagram of 1936 in which elliptical nebulae, which consist of more spherical groups of stars, split off into two prongs of spiral galaxies (with and without bars). The Atlas3D results suggest that this tuning fork should be replaced with a 'comb-like' diagram where elliptical galaxies are parallel to spirals and linked to them along the teeth of the comb while only a few true ellipticals are separated into the handle.

'According to our survey only a small fraction of elliptical galaxies, the 'slow rotators', are genuine spheroids. It reveals a strong family resemblance between elliptical and spiral galaxies once we can adjust for whether we are seeing them face-on or from the side,' said Dr Cappellari. 'This close relationship will need to be considered in any future models of how galaxies form. It's an exciting moment, after four years of work in the project, we have the final piece of the puzzle which enables us to say that text-books used to teach astronomy for over 70 years now need to be revised.'

The team, led by Dr Michele Cappellari of Oxford University's Department of Physics, Eric Emsellem, Davor Krajnovic (ESO, Germany) and Richard McDermid (Gemini, USA), compiled their maps of stellar motions from 40 nights of observations using the SAURON integral-field spectrograph at the 4.2-m William Hershel Telescope on the Canary Islands.

A report of the research is to be published in an upcoming issue of Monthly Notices of the Royal Astronomical Society. Lead author Dr Michele Cappellari was supported through a Royal Society Research Fellowship.


Story Source:

The above story is based on materials provided by University of Oxford. Note: Materials may be edited for content and length.


Journal Reference:

  1. Michele Cappellari et al. The Atlas3D project -- VII. A new look at the morphology of nearby galaxies: the kinematic morphology-density relation. Monthly Notices of the Royal Astronomical Society, 2011

Cite This Page:

University of Oxford. "Most elliptical galaxies are 'like spirals'." ScienceDaily. ScienceDaily, 15 July 2011. <www.sciencedaily.com/releases/2011/07/110714101631.htm>.
University of Oxford. (2011, July 15). Most elliptical galaxies are 'like spirals'. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2011/07/110714101631.htm
University of Oxford. "Most elliptical galaxies are 'like spirals'." ScienceDaily. www.sciencedaily.com/releases/2011/07/110714101631.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Space & Time News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. 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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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