On October 25, 2023, an image of the aftermath of a collision between two spiral galaxies was captured by the Gemini South telescope, located on Cerro Pachón mountain in Chile. The image shows bands of interstellar dust and gas, revealing the tangled remnants of the collision.
This collision occurred about a billion years ago and resulted in the formation of the chaotic elliptical galaxy NGC 7727. The process of spiral galaxies merging into elliptical galaxies is common and is thought to be the origin of all elliptical galaxies, according to NASA.
What makes NGC 7727 particularly interesting is what’s happening to the nuclei of the two formerly separate galaxies. Each galaxy contains a supermassive black hole, and their proximity, at just 1,600 light-years apart, causes a gravitational tug-of-war that has led to the chaotic arrangement of stars and nebulas in NGC 7727. The supermassive black holes are not equally matched, with one being 6.3 million times the mass of the sun, and the other being as massive as 154 million suns. It is predicted that these two black holes will merge in about 250 million years, producing gravitational waves.
NGC 7727 also provides insight into the future of our Milky Way galaxy, which is expected to merge with the Andromeda galaxy (M31) in about 4 billion years. This image was taken by