Galaxies can be elliptical, spiral, spiral barred, or irregular. They are sometimes subdivided. Spiral galaxies were determined to be the most frequent type of galaxy in the Universe. Other sorts of galaxies exist based on size and other distinct qualities. Large galaxies are frequently elliptical, with a trillion or more stars. They can be up to a million light-years across, ten times the Milky Way.
The Universe is home to billions of galaxies, and each galaxy hosts billions of stars. Our own Galaxy, the Milky Way, contains hundreds of billions of these stars, and there are four types of galaxies in the Universe – spiral, elliptical, irregular, and lenticular. Here’s a closer look at each one.
Strangely, the tiniest galaxies are elliptical. The oldest and furthest galaxy known is GN-z11. The galaxy formed 400 million years after the Big Bang.
In general, galaxies range from 1.000 to 100.000 parsecs in diameter.
Galaxies in a Spiral
There is also a new class of galaxy that has recently been discovered; it’s called lenticular and they’re quite rare, only accounting for about 2 percent of all galaxies in our universe. Lenticular Galaxies have an oval shape with a round core but no discernible structure around it.
They have a flat, spinning disc with a central bulge and spiral arms surrounding it. The spinning motion can reach rates of several hundred kilometers per second. This frequently causes the disk’s matter to spiral into a characteristic spiral shape, similar to a cosmic pinwheel. A supermassive black hole is frequently found in the bulge in the center, which is made up of older, dimmer stars.
The bulge’s disc of stars tends to divide into arms that circle the galaxy. Many young stars are born in these spiral arms because they contain a lot of gas and dust. Before their sudden demise, these youthful stars shine brightly. The tightness of the spiral, the lumpiness of the arms, and the overall size of the central bulge are all factors that can be used to classify spiral galaxies.
These discrepancies can be depicted by the relative amounts of gas and dust contained within these galaxies. Andromeda is a spiral galaxy that is exquisite in every way.
Galaxies with Elliptical Shapes
Elliptical galaxies have a spherical, elongated shape with no nucleus or bulge in the center. The galaxy is brighter in the center and less brilliant toward the galaxy’s outer edges, despite the absence of a core.
Older reddish stars dominate their light. They don’t appear to have spiral arms, either. An elliptical galaxy has stars, gases, and other stuff scattered throughout it. Elliptical galaxies can be virtually circular or long and cigar-shaped, depending on their shape.
Individual stars orbit the center of an elliptical galaxy, but their orbits do not all point in the same direction as in spiral galaxies. As a result, ellipticals don’t appear to revolve in a predictable pattern.
Galaxies with Odd Shapes
Irregular galaxies have no distinct shape, although they are in perpetual motion like all other galaxies. They have a disheveled appearance due to the lack of a nuclear bulge or spiral arm traces.
Some irregular galaxies began as spiral or elliptical galaxies before being warped by an uneven external gravitational influence. Irregular galaxies may have a lot of gas and dust in them. Irregular galaxies are typically small, weighing roughly a tenth of the mass of the Milky Way.
Spiral Galaxies with Bars
Regular spiral galaxies have the same properties and functions as barred spiral galaxies. Still, they additionally contain a bar of brilliant stars that runs down the bulge’s center and extends into the disc. The brilliant bulge has little activity and is primarily made up of older, red stars. A lot is going on in the bar and arms, including star formation.
FAQ
What is the rarest type of galaxy?
The “green bean” galaxy, often referred to as Hanny’s Voorwerp, is thought to be the rarest kind of galaxy. These galaxies, which were found in 2007 as part of the Galaxy Zoo project by Dutch schoolteacher Hanny van Arkel, are distinguished by their unusual greenish hue. The unusually rare phenomena known as Hanny’s Voorwerp is believed to have its unique color due to oxygen being ionized by a quasar located in the center of the galaxy. Because green bean galaxies are rare, astronomers find them particularly interesting because studying them could shed light on the intricate interactions between quasars, galaxies, and the interstellar medium. The cosmos is wide and diverse, as seen by the rarity of these galaxies, which begs for more study and research to solve its mysteries.
What is the most common galaxy type?
The elliptical galaxy is the most prevalent kind of galaxy in the observable universe. The distinctive spiral arms present in spiral galaxies are absent from elliptical galaxies, which are defined by their rounded and ellipsoidal morphologies. Compared to spiral galaxies, they are made of older stars, have less interstellar matter, and show less continuing star formation. Large galaxy clusters are home to many elliptical galaxies, and their creation and evolution are largely influenced by mergers and gravitational interactions. The frequency of elliptical galaxies indicates that processes like galaxy mergers and interactions have been important in creating the cosmos over cosmic time. Their abundance also adds to the overall diversity of galactic shapes.
What type of galaxy is Andromeda?
A spiral galaxy, the Andromeda Galaxy is often referred to as Messier 31 or M31. It belongs to the Local Group, a group of galaxies that also includes the Milky Way, the Triangulum Galaxy, and several other smaller galaxies. It is the closest spiral galaxy to the Milky Way. The distinctive spiral arms of Andromeda are made up of complex dust lanes, young blue stars, and areas of active star formation. At about 220,000 light-years in diameter, it is larger than the Milky Way. It is anticipated that in roughly 4 billion years, the Andromeda Galaxy, which is headed straight toward the Milky Way, will merge with our galaxy to produce a new, larger elliptical galaxy. Understanding the characteristics and development of the Andromeda Galaxy advances our knowledge of the dynamics and life cycles of spiral galaxies and the larger cosmic environment.
Is Dwarf a galaxy?
Yes, one kind of galaxy is a dwarf galaxy. Compared to larger galaxies like the Milky Way and Andromeda, dwarf galaxies are distinguished by their comparatively tiny size, reduced luminosity, and fewer stars. Dwarf galaxies are fundamental components of the universe’s cosmic web, despite their small size. There are two primary categories of them: dwarf elliptical galaxies, which are more rounded in shape, and dwarf irregular galaxies, which lack a clear structure. Throughout the universe, dwarf galaxies are widely distributed and frequently seen orbiting around larger galaxies as companions. Dwarf galaxies are difficult to find and study due to their tiny size and decreased luminosity, yet they are essential to our knowledge of the formation, evolution, and distribution of material in the universe.
How do we classify galaxies?
Based on their outward look, galaxies are categorized using a scheme that is widely recognized as the Hubble sequence or the Hubble tuning fork diagram. This categorization technique was created in the 1920s by astronomer Edwin Hubble and divides galaxies into three main categories: spiral galaxies, elliptical galaxies, and irregular galaxies. Spirals are further subdivided into barred spirals (SBa, SBb, and SBc) and standard spirals (Sa, Sb, and Sc) according to the tightness of their spiral arms. Based on how elliptical they are, galaxies are categorized into E0 (almost spherical) and E7 (extremely elongated) groups. The defining forms of spirals and ellipticals do not apply to irregular galaxies, which are typically characterized by a more chaotic appearance. To further improve galaxy classifications, astronomers also take into account additional factors like the quantity of interstellar material, the prominence of spiral arms, and the existence or absence of a central bar. This system of visual classification offers a useful foundation for arranging and examining the vast variety of galaxies found in the universe.
