The shape of the galaxy NGC 428 distorted by a galaxy merger

Picture of the galaxy NGC 428 taken by the Hubble Space Telescope (Photo ESA/Hubble and NASA and S. Smartt (Queen's University Belfast))
Picture of the galaxy NGC 428 taken by the Hubble Space Telescope (Photo ESA/Hubble and NASA and S. Smartt (Queen’s University Belfast))

A photograph of the galaxy NGC 428 taken by the Hubble Space Telescope shows its distorted and warped structure. Together with traces of a significant amount of stars being formed, it’s the sign of the merger between two galaxies. For this reason, its appearance could give us an idea of ​​what will happen in a few billion years to the Milky Way in its merger with Andromeda.

The galaxy NGC 428 was discovered in 1786 by astronomer William Herschel. Its distance is about 48 million light years from Earth. Some studies focused on the birth of stars in NGC 428 and in 2013 a type Ia supernova designated SN2013ct was discovered close to its core by Stuart Parker of the BOSS (Backyard Observatory Supernova Search) project in Australia and New Zealand.

This recent image was taken using the  Hubble Space Telescope’s Advanced Camera for Surveys (ACS) and the Wide Field and Planetary Camera 2 (WFPC2) instruments. It shows only a part of the galaxy NGC 428 with the signs of the galactic merger that distort its shape.

Generally, spiral galaxies have a regular shape but when two galaxies start merging the shape of both gets distorted. It’s unlikely that there are actual collisions because the space between stars is huge but the gravitational effects are felt considerably on gas clouds.

During a galactic merger, the gas clouds of the two galaxies, which can have even very high extensions, can really merge and this causes a considerable shock and the creation of concentrations of hot gases. The result is the birth of new stars in quantity, just as it was observed in the galaxy NGC 428.

Technically, the galaxy NGC 428 is of the barred spiral type. This type of galaxy has a bulge with two extensions of stars that resemble a bar that runs through its core. The Milky Way is a galaxy of this type. In NGC 428 this shape is distorted.

In the distant future, the Milky Way will start merging with the Andromeda galaxy to form a single giant galaxy. During that process, the images that the astronomers of that era could get maybe will be similar to those now they can get of NGC 428.



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