A new image from the Hubble Space Telescope reveals the vibrant star-forming regions of Messier 33 (M33), also known as the Triangulum Galaxy. This spiral galaxy is the third-largest member of the Local Group of galaxies, after Andromeda and our own Milky Way. Measuring only 60,000 light-years across, M33 is about half the size of the Milky Way and is located nearly 3 million light-years from Earth.
The Triangulum Galaxy is a ‘hotbed of starbirth,’ forming stars at a rate 10 times higher than the neighboring Andromeda galaxy, according to NASA. Interestingly, M33’s neat, organized spiral arms indicate little interaction with other galaxies, meaning its rapid starbirth isn’t fueled by galactic collisions. Instead, new stars are born from ample amounts of dust and gas within the galaxy itself.
Collisions between massive ionized hydrogen clouds, known as H-II regions, create high-mass stars, which can be seen in the new Hubble image. The large reddish clouds in the Hubble photo represent these pockets of ionized hydrogen, which, along with the dark streams of gas, fuel the galaxy’s rapid star formation.
The apparent graininess of the image is actually swarms of countless stars. M33 is one of less than 100 galaxies close enough for telescopes like Hubble to resolve individual stars.
However, unlike most spiral galaxies, M33 lacks a central bulge, which would otherwise house a supermassive black hole. As a result, M33 is classified as a ‘pure disk galaxy,’ a type of galaxy believed to make up around 15-18% of all galaxies in the universe.
The new Hubble image, released on August 21, was taken as part of a larger study on the interstellar medium, star-formation processes, and stellar evolution. Scientists hope this research will offer insight on the possible future collision between M33 and the Andromeda and Milky Way galaxies.
