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Trapezium (astronomy)
The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei. On 4 February 1617 he sketched three of the stars ( A, C and D), but missed the surrounding nebulosity.Galileo Galilei: Siderius Nuncius, Venice, 1610. English Translation published at Bard College, Hudson NY" October 9, 2003 English TranslatioOriginal Latin versio/ref>Tom Pope and Jim Mosher: Galilean telescope homepage" March 17, 2006 , "Some have expressed puzzlement that in his text Galileo does not mention the nebulosity (known in modern nomenclature as M42) enveloping these stars. ... Galileo believed, as he explains in ''Sidereus Nuncius'', that what looks nebulous to the eye is resolved into stars by his telescope; what looks nebulous through his telescope could presumably also be resolved into stars by a still larger and more powerful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Cluster
An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. They are loosely bound by mutual gravity, gravitational attraction and become disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a migration to the main body of the galaxy and a loss of cluster members through internal close encounters. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral galaxy, spiral and irregular galaxy, irregular galaxies, in which active star formation is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta1 Orionis D
Theta1 Orionis D (θ1 Orionis D) is a member of the Trapezium open cluster that lies within the Orion Nebula. It is a B class blue main sequence star with several faint companions. θ1 Orionis consists of multiple components, primarily the four stars of the Trapezium cluster ( A, B, C, and D) all within one arc-minute of each other. θ2 Orionis is a more distant grouping of three main stars plus several fainter companions, 1-2 arc-minutes from θ1. θ1 D itself has a faint optical companion 1.4" away and a spectroscopic companion in a 40-day orbit. Infrared Optical Telescope Array observations suggest another companion at 18.6 mas. References {{DEFAULTSORT:Theta1 Orionis D Orionis, Theta1, D Orionis, 41, D Orion (constellation) B-type main-sequence stars 037023 1896 Events January–March * January 2 – The Jameson Raid comes to an end, as Jameson surrenders to the Boers. * January 4 – Utah is admitted as the 45th U.S. state. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Runaway Stars
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as the internal kinematics of more distant galaxies. Measurement of the kinematics of stars in different subcomponents of the Milky Way including the thin disk, the thick disk, the bulge, and the stellar halo provides important information about the formation and evolutionary history of our Galaxy. Kinematic measurements can also identify exotic phenomena such as hypervelocity stars escaping from the Milky Way, which are interpreted as the result of gravitational encounters of binary stars with the supermassive black hole at the Galactic Center. Stellar kinematics is related to but distinct from the subject of stellar dynamics, which involves the theoretical study or modeling of the motions of stars under the influence of gravity. Stellar-dyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (). However, they can fuse deuterium ( 2H), and the most massive ones (> ) can fuse lithium ( 7Li). Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Despite their name, to the naked eye, brown dwarfs would appear in different colors depending on their temperature. The warmest ones are possibly orange or red, while cooler brown dwarfs would likely appear magenta or black to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
