Dwarf galaxy

A dwarf galaxy is a small galaxy composed of up to several billion stars, a small number compared to our own Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

Formation of dwarf galaxies

Current theory states that most galaxies, including dwarf galaxies, form in association with dark matter, or from gas that contains metals. However, NASA's Galaxy Evolution Explorer space probe identified new dwarf galaxies forming out of gases lacking metals. These galaxies were located in the Leo Ring, a cloud of hydrogen and helium around two massive galaxies in the constellation Leo.

Because of their small size, dwarf galaxies have been observed being pulled toward and ripped by neighbouring spiral galaxies, resulting in galaxy merger.

Milky Way

The Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye. The term "Milky Way" is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος (galaxías kýklos, "milky circle"). From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies—now estimated to number as many as 200 billion galaxies in the observable universe.

The Milky Way is a barred spiral galaxy that has a diameter usually considered to be about 100,000–120,000 light-years but may be 150,000–180,000 light-years. The Milky Way is estimated to contain 100–400 billion stars, although this number may be as high as one trillion. There are probably at least 100 billion planets in the Milky Way. The Solar System is located within the disk, about 27,000 light-years from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The stars in the inner ≈10,000 light-years form a bulge and one or more bars that radiate from the bulge. The very center is marked by an intense radio source, named Sagittarius A*, which is likely to be a supermassive black hole.

SpaceEngine

SpaceEngine (stylized as "Space Engine") is a proprietary 3D astronomy program and game engine developed by Russian astronomer and programmer Vladimir Romanyuk. Using real astronomical catalogs and procedural generation, it creates a three-dimensional planetarium representing the entire universe. Users can travel through space in any direction or speed, and forwards or backwards in time. SpaceEngine is in beta status, and is currently freeware for Microsoft Windows. It uses pseudo-random numbers to procedurally create any kind of planetary system, nebula or galaxy.

One of the main features of the program is its scientific accuracy. Cataloged objects are based on real data, while procedural objects are built around the cataloged universe using realistic generation algorithms. Properties of objects, such as temperature, mass, radius, etc., are presented to the user on the HUD and in an accessible information window. Users can observe objects from small spacecraft to galaxy clusters, similar to other simulators such as Celestia. SpaceEngine includes thousands of real objects, including stars from the Hipparcos catalog, galaxies from the NGC and IC catalogs, several well-known nebulae, and all known exoplanets and their stars.

Dwarf

Dwarf may refer to:

Modern popular culture

Other uses

See also

Sculptor Dwarf Galaxy

The Sculptor Dwarf Galaxy (also called the Sculptor Dwarf Elliptical Galaxy or the Sculptor Dwarf Spheroidal Galaxy) is a dwarf spheroidal galaxy that is a satellite of the Milky Way. The galaxy lies within the constellation Sculptor. It was discovered in 1937 by Harlow Shapley using the 24-inch Bruce refractor at Boyden Observatory. The galaxy is located about 290,000 light-years away from the Solar System. The Sculptor Dwarf contains only 4 percent of the carbon and other heavy elements in our own galaxy, the Milky Way, making it similar to primitive galaxies seen at the edge of the universe.

Metallicity

The metallicity of Sculptor dwarf appears to be broken up into two distinct groups, one with [Fe/H] = -2.3 and the other with [Fe/H] = -1.5. Similar to many of the other Local Group galaxies, the older metal-poor segment appears more extended than the younger metal-rich segment.

Gallery

Sculptor Dwarf Galaxy taken by the 2.2-meter MPG/ESO telescope.

Sculptor Dwarf Galaxy taken by the 2.2-meter MPG/ESO telescope.