Tmall triple galaxy

NASA released a photo of the triple galaxy "Arp 195" taken by the Hubble Space Telescope, and the three galaxies in the center merged with each other under the action of gravity. This is a group of galaxies located in the northern part of the Tmall constellation, about 763 million light years away from the Earth. The celestial system contains at least three galaxies with a width of about 200,000 light years, two of which have been highly fused, and the stars and gas of the third galaxy extend outward due to gravity, forming a tidal tail with a length of about 200,000 light years.

Tmall is one of the northern constellations. It is a small constellation between Ursa major and Gemini.

Constellation myth

Tmall refers to Lynceus, one of Argo's ship heroes. Lynceus's eyesight is the sharpest in the world, and he can even see things in the underworld. His eyesight is like a night cat. Lynceus and his brother Iddas got together with Dioscuri brothers (Gemini) casto Er and Polydeuces/Pollux for two women, Iddas killed casto Er and Polonius killed Lynceus. When Iddas attacked Polonius, he was hacked to death by his father Zeus.

Tidal tails, which extend from galaxies into space, are slender regions of stars and interstellar gas. Tidal tails are the result of tidal force interaction between interacting galaxies. Examples of galaxies with tidal tails include tadpole galaxies and twin galaxies. Tidal force can inject a considerable amount of gas from galaxies into tidal tails, such as tentacle galaxies, and nearly half of the visible gaseous substances exist in the tail structure. In the tidal tails of these galaxies, about 10% of the stars are formed in the tails. Generally speaking, about 1% of star formation in the universe occurs at the tidal tail.

Some interacting galaxies are like tentacle galaxies, with two obvious tails, while others have only one tail. Most tidal tails bend slightly as galaxies rotate. Those seemingly straight tidal tails may actually be curved, but they are straight when viewed from the side.