Featured Research

from universities, journals, and other organizations

A trick of perspective: Chance alignment mimics a cosmic collision

Date:
June 14, 2012
Source:
European Space Agency (ESA)
Summary:
The NASA/ESA Hubble Space Telescope has produced a highly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two just happen to appear in the same direction from our vantage point.

The NASA/ESA Hubble Space Telescope has produced an incredibly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two are in chance alignment from our vantage point.
Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and W. Keel (University of Alabama)

The NASA/ESA Hubble Space Telescope has produced a highly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two just happen to appear in the same direction from our vantage point.

NGC 3314A and B might look like they are in the midst of a galactic pile-up, but they are in fact separated by tens of millions of light years of void. Their apparent proximity is simply a trick of perspective.

How do we know this? The biggest hint as to whether galaxies are interacting is usually their shapes. The immense gravitational forces involved in galactic mergers are enough to pull a galaxy out of shape long before it actually collides. Deforming a galaxy like this does not just warp its structure, but it can trigger new episodes of star formation, usually visible as bright blue stars and glowing nebulae.

In the case of NGC 3314, we do indeed see deformation in the foreground galaxy (called NGC 3314A, NGC 3314B lies in the background), but this is almost certainly misleading. NGC 3314A's deformed shape, particularly visible below and to the right of the core, where streams of hot blue-white stars extend out from the spiral arms, is not due to interaction with the galaxy in the background.

Studies of the motion of the two galaxies indicate that they are both relatively undisturbed, and that they are moving independently of each other. This indicates in turn that they are not, and indeed have never been, on any collision course. NGC 3314A's warped shape is likely due instead to an encounter with another galaxy, perhaps nearby NGC 3312 (visible to the north in wide-field images) or another nearby galaxy.

The chance alignment of the two galaxies is more than just a curiosity, though. It greatly affects the way the two galaxies appear to us.

NGC 3314B's dust lanes, for example, appear far lighter than those of NGC 3314A. This is not because that galaxy lacks dust, but rather because they are lightened by the bright fog of stars in the foreground. NGC 3314A's dust, in contrast, is backlit by the stars of NGC 3314B, silhouetting them against the bright background.

Such an alignment of galaxies is also helpful to astronomers studying gravitational microlensing, a phenomenon that occurs when stars in one galaxy cause small perturbations in the light coming from a more distant one. Indeed, the observations of NGC 3314 that led to this image were carried out in order to investigate this phenomenon.

This mosaic image covers a large field of view (several times the size of an individual exposure from Hubble's Advanced Camera for Surveys). Thanks to a long exposure time of more than an hour in total exposure time for every frame, the image shows not only NGC 3314, but also many other more distant galaxies in the background.

The colour composite was produced from exposures taken in blue and red light.


Story Source:

The above story is based on materials provided by European Space Agency (ESA). Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency (ESA). "A trick of perspective: Chance alignment mimics a cosmic collision." ScienceDaily. ScienceDaily, 14 June 2012. <www.sciencedaily.com/releases/2012/06/120614093942.htm>.
European Space Agency (ESA). (2012, June 14). A trick of perspective: Chance alignment mimics a cosmic collision. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2012/06/120614093942.htm
European Space Agency (ESA). "A trick of perspective: Chance alignment mimics a cosmic collision." ScienceDaily. www.sciencedaily.com/releases/2012/06/120614093942.htm (accessed August 20, 2014).

Share This




More Space & Time News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Space to Ground: Hello Georges

Space to Ground: Hello Georges

NASA (Aug. 18, 2014) Europe's ATV-5 delivers new science and the crew tests smart SPHERES. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
Powered by NewsLook.com
Tiny Satellites, Like The One Tossed From ISS, On The Rise

Tiny Satellites, Like The One Tossed From ISS, On The Rise

Newsy (Aug. 18, 2014) The Chasqui I, hand-delivered into orbit by a Russian cosmonaut, is one of hundreds of small satellites set to go up in the next few years. Video provided by Newsy
Powered by NewsLook.com
This Week @ NASA, August 15, 2014

This Week @ NASA, August 15, 2014

NASA (Aug. 15, 2014) Carbon Observatory’s First Data, ATV-5 Delivers Cargo, Cygnus Departs Station and more... Video provided by NASA
Powered by NewsLook.com
Space Shuttle Replica Hoisted for Landmark Exhibit

Space Shuttle Replica Hoisted for Landmark Exhibit

Reuters - US Online Video (Aug. 14, 2014) The space shuttle replica Independence has been hoisted atop Space Center Houston's shuttle carrier aircraft, creating a monument to the shuttle program which will open to the public next year. 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