The NGC 5917 galaxy seen on its own by the Hubble Space Telescope

The galaxy NGC 5917 (Image ESA/Hubble & NASA)
The galaxy NGC 5917 (Image ESA/Hubble & NASA)

An image captured by the Hubble Space Telescope of the galaxy NGC 5917 just published shows it on its own. This could be considered normal but this is a special case because it’s a galaxy known mainly for its interaction with a neighbor known as MCG-01-39-003. Those are interacting galaxies, an expression used when there are galaxies that affect each other with their mutual gravity. NGC 5917 and MCG-01-39-003 could end up merging.

The Galaxy NGC 5917, also known as LEDA 54809, IRAS 15188-0711 or MCG-01-39-00, is about 87 million light years from Earth and is a spiral galaxy with a diameter of about 40,000 light years. Due to its distance, its light is dim and requires a telescope to be seen, so much that it was only discovered only in 1835 by British astronomer William Herschel, who didn’t notice its neighbor MCG-01-39-003, which is even dimmer.

This pair of galaxies has been extensively studied over time. In recent years, for example, they’ve been the protagonists of astronomical chronicles on some occasions thanks to supernovas sighted in the area. In 1990 a type II supernova called SN 1990Q was identified. In 2005 a type Ia supernova called SN2005cf was identified. In 2013 a supernova called PSN J15213475-0722183 was identified.

ESO’s VLT is one of the telescopes used to study the supernova SN2005cf. It was an exceptional event because it’s located in the “bridge” between the galaxies NGC 5917 and MCG-01-39-003, as shown in the bottom image. The researchers who studied it calculated that materials were ejected from that explosion at speeds around 15,000 kps (about 33,500,000 mph).

The supernova SN2005cf was an interesting case because it’s probably the product of the effects of the interaction between the galaxies NGC 5917 and MCG-01-39-003. Gravitational interactions can cause shock in the gas and dust clouds even when there is no galactic merger with the result that the formation of new stars is triggered. Massive stars have a short life so after several million years they start exploding in supernova such as the one found in 2005.

The new image of the NGC 5917 galaxy was created by combining various photos taken by the Hubble Space Telescope’s Wide Field Camera 3 (WFC3) instrument. The study of its interactions with PSN J15213475-0722183 is important but a detailed image allows researchers to study it in the best way.

The galaxies NGC 5917 and MCG-01-39-003 (Image ESO)
The galaxies NGC 5917 and MCG-01-39-003 (Image ESO)

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