Featured Research

from universities, journals, and other organizations

Stream of stars in Andromeda satellite galaxy shows cosmic collision

Date:
February 23, 2014
Source:
University of Copenhagen - Niels Bohr Institute
Summary:
The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. Researchers have detected a stream of stars in one of the Andromeda Galaxy's outer satellite galaxies, a dwarf galaxy called Andromeda II. This galaxy is very small -- less than one percent of the Milky Way. The movement of the stars tells us that what we are observing is the remnant of a merger between two dwarf galaxies. Mergers between galaxies of such low mass has not been observed before.

The Andromeda Galaxy is a large spiral galaxy like our galaxy, the Milky Way. It is located about 2.3 million light years away and can be seen with the naked eye. The satellite galaxy Andromeda II is located in a distant orbit approximately 600,000 light years from the center of the great Andromeda Galaxy.
Credit: NASA

The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. Researchers from the Niels Bohr Institute, among others, have detected a stream of stars in one of the Andromeda Galaxy's outer satellite galaxies, a dwarf galaxy called Andromeda II. The movement of the stars tells us that what we are observing is the remnant of a merger between two dwarf galaxies. Mergers between galaxies of such low mass has not been observed before. The results are published in the scientific journal, Nature.

The galaxies in the early universe started off small and the theory of the astronomers is that the baby galaxies gradually grew larger and more massive by constantly colliding with neighbouring galaxies to form new, larger galaxies. Large, massive galaxies constantly attract smaller galaxies due to gravity and they eventually merge together and grow even larger.

But not all of the small galaxies are being 'eaten' by the large galaxies. Some of them remain in an orbit around the large galaxy. The largest galaxy in our cosmic neighborhood is the Andromeda Galaxy, which is about 2.3 million light years away. Like our own galaxy, the Milky Way, Andromeda is a large spiral galaxy.

Swarm of small galaxies

Andromeda is surrounded by a swarm of small galaxies -- astronomers have counted more than 20. They have names like Andromeda I, II, III, IV...etc. Researchers from the Dark Cosmology Centre at the Niels Bohr Institute, among others, have analysed measurements of the stars in the dwarf galaxy Andromeda II and made a surprising discovery.

"Stars in a dwarf galaxy often move around at random, but this is not exactly the case for Andromeda II. In particular we could see that a stream of stars is moving around differently than the rest in a very coherent way. These stars are situated in an almost complete ring and are rotating around the centre of the galaxy," explains astrophysicist Nicola C. Amorisco, Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen.

Cosmic collisions

The dwarf galaxy Andromeda II is very small -- less than one percent of the Milky Way. The rotating stream of stars in the galaxy is entirely made up of old stars and from their properties, researchers can draw conclusions about this dramatic cosmic event.

"What we are seeing is the remains of a collision between two dwarf galaxies, which had a dramatic effect on the dynamics of the remnant," says Nicola C. Amorisco.

He explains that mergers between such small galaxies are expected during the galaxy formation process, but are rare at present times and had hitherto not been seen. Andromeda II is the least massive known example of merging of galaxies so far and illustrates the scale-free character og the formation og galaxies down to the lowest galactic mass scales.


Story Source:

The above story is based on materials provided by University of Copenhagen - Niels Bohr Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. N. C. Amorisco, N. W. Evans, G. van de Ven. The remnant of a merger between two dwarf galaxies in Andromeda II. Nature, 2014; DOI: 10.1038/nature12995

Cite This Page:

University of Copenhagen - Niels Bohr Institute. "Stream of stars in Andromeda satellite galaxy shows cosmic collision." ScienceDaily. ScienceDaily, 23 February 2014. <www.sciencedaily.com/releases/2014/02/140223131709.htm>.
University of Copenhagen - Niels Bohr Institute. (2014, February 23). Stream of stars in Andromeda satellite galaxy shows cosmic collision. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2014/02/140223131709.htm
University of Copenhagen - Niels Bohr Institute. "Stream of stars in Andromeda satellite galaxy shows cosmic collision." ScienceDaily. www.sciencedaily.com/releases/2014/02/140223131709.htm (accessed September 20, 2014).

Share This



More Space & Time News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) — The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) — NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) — Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama 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:
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