Messier 61 is a type of galaxy known as a starburst galaxy. Starburst galaxies have an abnormally high rate of star formation, hungrily using up their reservoir of gas in a very short period of time (in astronomical terms). However, that’s not the only activity we believe is going on within M61; deep at its heart there is thought to be a supermassive black hole that is violently spewing out radiation.
Despite its inclusion in the Messier Catalogue, Messier 61 was actually discovered by Italian astronomer Barnabus Oriani in 1779. Charles Messier also noticed this galaxy on the very same day as Oriani, but mistook it for a comet.
Image Credit: NASA
This Hubble image shows a massive galaxy about 4.6 billion light years away. Around that galaxy’s border are four bright arcs. They are images the same distant galaxy nicknamed the Sunburst Arc. The Sunburst Arc galaxy is almost 11 billion light-years away. Its light is lensed into multiple images by gravitational lensing of the nearer galaxy. The Sunburst Arc is one of the brightest lensed galaxies known, and its image is visible at least 12 times within the four arcs.
Video Credit: ESA / NASA / Rivera-Thorsen et al.
This is the dwarf galaxy known as NGC 1140. It lies 60 million light-years away in the constellation of Eridanus. It has an irregular form, much like the Large Magellanic Cloud, a small galaxy that orbits the Milky Way. This small galaxy is undergoing a starburst. Despite being only about one-tenth the size of the Milky Way, it is creating stars at about the same rate—the equivalent of one star the size of our sun being created per year. The galaxy is full of bright, blue-white, young stars.
Galaxies like NGC 1140 are of particular interest to astronomers because their composition makes them similar to the intensely star-forming galaxies in the early Universe, and those early Universe galaxies were the building blocks of present-day large galaxies like our Milky Way. Because they are so far away, the early Universe galaxies are harder to study, so these closer starbursting galaxies are a good substitute for studyingt galaxy evolution.
Its vigorous star formation eventually will have a very destructive effect on this small dwarf galaxy. When the larger stars in the galaxy die and explode as supernovae, the gas blown into space may escape the gravitational pull of the galaxy. The ejection of gas from the galaxy throws away one of the building blocks for future star formation. Thus, NGC 1140’s starburst cannot last for long.
Image Credit: ESA
This is an irregular galaxy named IC 10, a member of the Local Group — the nearby group of over 50 galaxies that includes the Milky Way. IC 10 is the closest-known starburst galaxy to us. It is the site of rapid star formation fueled by ample supplies of cool hydrogen gas. This gas condenses into vast molecular clouds which further contract into dense knots where pressures and temperatures reach a point sufficient to ignite nuclear fusion, and new stars are born.
Image Credit: ESA / NASA
NGC 1705 is a oddball irregular dwarf galaxy undergoing a starburst. It’s about 17 million light-years from the Earth in the constellation Pictor. Dwarf galaxies were probably the first systems to collapse and start forming stars in the early universe. They represent the building blocks from which more massive objects (such as spiral and elliptical galaxies) were formed through mergers. The remaining dwarf galaxies are thought to be the leftovers of the galaxy-formation process.
Image Credit: NASA