One of the largestglobular clusters in the Large Magellanic Cloud
Space news (September 20, 2015) – 160,000 light-years from Earth toward the constellation Dorado –
Held in the grip of its own gravity, globular cluster NGC 1783 orbits the Milky Way as part of the Large Magellanic Cloud, a region of space filled with star-forming regions like the Tarantula Nebula and LHA 120-N 11.
Lying in the southern hemisphere constellation Dorado, the typical symmetrical form and dense collection of suns near the center of NGC 1783 was first recorded by John Herschel around 1835.
Astrophysicists studied the color and brightness of individual suns within globular cluster NGC 1783 to estimate its age and history of star formation. Measurements indicate that despite its typical distribution of stars and shape this larger star cluster is only about 1.5 billion years old and during its lifespan has undergone at least two-star forming periods separated by 50 to 100 million years. Typically globular clusters viewed are several billion years of age.
The highs and lows of star formation in a globular cluster gives astrophysicists an indication of the density of gas available for new stars to form during its life span. During periods when dense gas is available for star formation, the most massive stars explode as supernovae, blowing away the gas needed for new stars to form. The reservoir of gas for new star formation is then replenished by less massive stars which live longer and die less violently. Once the reservoir of gas flows to denser, central regions of a star cluster, the second phase of star formation takes place, and a massive star with a short life spans once again blow off the gas. Astrophysicists think this cycle continues until the gas leftover can no longer sustain the formation of new stars.
One small cog of a vast wheel of the Virgo supercluster
The distance involved in traveling to the next galaxy is staggering to consider
The Messier Catalogue
Astronomy News – Astronomers looking upward into the night sky realised centuries ago that deep-sky objects are distributed unevenly about the night sky. French comet hunter Charles Messier (1730-1817) looking upward into the night sky through his time-machine-to-the-stars compiled a popular catalog of deep-sky objects. His catalogue contains high concentrations of deep-sky objects within the Milky Way above you, where open star clusters and star-forming areas that form them congregate.
Messier’s catalogue also contains entries on 16 objects he located near the border between the constellations Virgo and Coma Berenices. Star gazer William Herschel (1738-1822) and his son, John Herschel (1792-1871), recorded more than 200 celestial objects in this same region of the night sky. It would be in the 1920s and 1930s that astronomers would determine that these nebulous objects are in fact galaxies as big, or larger than, the Milky Way galaxy that constitute a cluster of galaxies far beyond the Milky Way.
Our Local Group of galaxies
Two decades later, French-born astronomer Gerard de Vaucouleurs (1918-1995) noted that the halo of galaxies surrounding what astronomers referred too as the Virgo cluster actually extends all the way to our Local Group of galaxies, which the Milky Way calls home. Today astronomers refer to this Local Group of galaxies as our Local Supercluster of galaxies.
Presently, astronomers believe our Local Supercluster extends 50 million light-years, from the center of the Virgo cluster. We’ll journey from the center of our Local Group to slightly beyond the Virgo cluster. Along the way we’ll stop at all of the galaxy groups and clusters containing at least three reasonably large galaxies and see what astronomers have determined about these distant celestial bodies in the night sky above you.
The first celestial object in the night sky we’ll journey to see is called the Ursa Major North Group, next we’ll travel to Ursa Major South Group, and then make our way to each of the galaxy groups and clusters in the Milky Way’s Local Group of neighbors.
The first leg of the human journey to the beginning of space and time