From Manu Garcia: “A trick of perspective, a random lineup mimics a cosmic collision, NGC 3314

Manu Garcia

NGC 3314

The NASA/ESA Hubble Space Telescope at has produced a very detailed picture of a pair of overlapping galaxies, called NGC 3314. The two galaxies appear to be in the middle of a collision, this is just a trick of perspective, as it happens The two appear in the same direction from our point of view.

NGC 3314 a and b can look like they’re in the middle of a galactic accumulation, but are actually separated by tens of millions of light years of emptiness. Apparent proximity is just a trick of perspective.

How do we know this? The biggest suggestion about if the galaxies are interacting is usually their forms. The immense gravitational forces involved in galactic mergers are enough to get a galaxy out of shape long before that really. Skew a galaxy like this not only distorts their structure, but can trigger new episodes of star formation, usually visible as bright blue stars and nebulas. Brilliant.

In the case of NGC 3314, we actually see deformation in the foreground galaxy (called NGC 3314, NGC 3314 b is on the bottom), but this is almost certainly misleading. THE DEFORMED SHAPE OF NGC 3314 a particularly visible below and to the right of the nucleus, where streams of white stars stretches and hot out of the spiral arms, is not due to the interaction with the galaxy at the bottom.

Study of motion of the two galaxies indicates that they are both relatively undisturbed and that move independently of each other. This indicates that they are not, and in fact have never been in any collision course. How crooked of NGC 3314 is probably due to an encounter with another galaxy, maybe near NGC 3312 (visible north in wide field imaging) or another nearby galaxy.

The alignment of the two galaxies is more than just a curiosity. Much affects the way in which the two galaxies we appear.

Dust Lanes of NGC 3314 b, for example, they seem much lighter than those of NGC 3314 a. This is not because that galaxy lacks dust, but because they are illuminated by the bright fog of stars in the foreground. The dust of NGC 3314, by contrast, is backlit by the stars of NGC 3314 b siluciendo against the bright background.

Such a lineup of galaxies is also useful for astronomers who study the gravitational microlensing, a phenomenon that occurs when the stars in a galaxy cause small disturbances in the light from a more distant.

Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

In fact, the observations of the NGC 3314 which led to this image were carried out in order to investigate this phenomenon.

This image in mosaic covers a wide field of view (several times the size of a solo exhibition of Hubble’s advanced camera for surveys). Thanks to a long exposure time of over 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 Color Composite was produced from exposures taken in blue and red light.

The Hubble Space Telescope is a project of international cooperation between ESA [15%] and NASA.

Photo Credit:
Hubble Heritage (STScI / Aura)-Esa / Hubble collaboration, and w. Keel (University of Alabama)

The data in this image of NGC 3314 were incorporated in the hidden treasures of Hubble processing processing contestants Andre you Hoeven and N. Moushon. Hidden Treasures is an initiative to invite the astronomy enthusiasts to search the archive of hubble stunning images that have never been seen by the general public. The competition is now closed and the winners will be announced soon.

See the full article here.

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