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Norma (constellation)
Norma is a small constellation in the Southern Celestial Hemisphere between Ara and Lupus, one of twelve drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenter's square, a set square or a level. It remains one of the 88 modern constellations. Four of Norma's brighter stars—Gamma, Delta, Epsilon and Eta—make up a square in the field of faint stars. Gamma2 Normae is the brightest star with an apparent magnitude of 4.0. Mu Normae is one of the most luminous stars known, with a luminosity between a quarter million and one million times that of the Sun. Four star systems are known to harbour planets. The Milky Way passes through Norma, and the constellation contains eight open clusters visible to observers with binoculars. The constellation also hosts Abell 3627, also called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carpenter's Square
The steel square is a tool used in carpentry. Carpenters use various tools to lay out structures that are square (that is, built at accurately measured right angles), many of which are made of steel, but the name ''steel square'' refers to a specific long-armed square that has additional uses for measurement, especially of various angles. It consists of a long, wider arm and a shorter, narrower arm, which meet at an angle of 90 degrees (a right angle). Today the steel square is more commonly referred to as the framing square or carpenter's square, and such squares are no longer invariably made of steel (as they were many decades ago); they can also be made of aluminum or polymers, which are light and resistant to rust. The longer wider arm is wide, and is called the blade; the shorter narrower arm, is wide, and is called the tongue. The square has many uses, including laying out common rafters, hip rafters and stairs. It has a diagonal scale, board foot scale and an octagonal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-square
A T-square is a technical drawing instrument used by draftsmen primarily as a guide for drawing horizontal lines on a drafting table. The instrument is named after its resemblance to the letter T, with a long shaft called the "blade" and a short shaft called the "stock" or "head". T-squares are available in a range of sizes, with common lengths being , , , and . In addition to drawing horizontal lines, a T-square can also be used with a set square to draw vertical or diagonal lines. The T-square usually has a transparent edge made of plastic which should be free of nicks and cracks in order to provide smooth, straight lines. T-squares are also used in other industries, such as construction. For example, drywall T-squares are typically made of aluminum and have a long tongue, allowing them to be used for measuring and cutting drywall. In woodworking, higher-end table saws often have T-square fences attached to a rail on the front side of the table, providing improved accura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norma Arm
The Norma Arm is a minor spiral arm of the Milky Way extending from and around its central hub region. The inner portion of the Arm is called the ''Norma Arm'' in narrow meaning. The outer part of it is identified either with the Cygnus Arm, which lies outside the Perseus Arm, or the Outer Arm, which is located farther away from the center of the Galaxy than the Cygnus Arm. The Norma Arm begins from the Galactic Center, and extends outward to a radius of . It is named for the Norma (constellation), Norma constellation, through which the Arm as seen from Earth passes. Like many other galaxies of similar type, the Milky Way consists of a large mass of stars shaped into the form of a relatively flat disc by gravity. The disc is rotating, with the dense central body of stars moving at greater speeds than those toward the rim of the disc. As a result, the pattern of stars within the Galaxy as viewed from directly above or below the disc has formed into a spiral. Because of localised ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Cluster
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-largest known gravitationally bound structures in the universe after galaxy filaments and were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered. One of the key features of clusters is the intracluster medium (ICM). The ICM consists of heated gas between the galaxies and has a peak temperature between 2–15 keV that is dependent on the total mass of the cluster. Galaxy clusters should not be confused with ''galactic clusters'' (also known as open clusters), which are star clusters ''within'' galaxies, or with globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as galaxy groups rather than clusters of galaxies. The galaxy groups a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norma Cluster
The Norma Cluster (ACO 3627 or Abell 3627) is a rich cluster of galaxies located near the center of the Great Attractor; it is about distant. Although it is both nearby and bright, it is difficult to observe because it is located in the Zone of Avoidance, a region near the plane of the Milky Way. Consequently, the cluster is severely obscured by interstellar dust at optical wavelengths. Its mass is estimated to be on the order of 1015 solar masses. ESO 137-001, an example of a jellyfish galaxy, is located in Abell 3627. See also * List of galaxy groups and clusters * Coma Cluster * Eridanus Cluster * Fornax Cluster * Virgo Cluster * X-ray astronomy References External links ESO Press Photos 46a-j/99* NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ... Image o ... [...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] |
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "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. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object. In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the luminosity of the Sun, ''L''⊙. Luminosity can also be given in terms of the astronomical magnitude system: the absolute bolometric magnitude (''M''bol) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or filter band. In contrast, the term ''brightness'' in astronomy is generally used to refer to an object's apparent brightness: that is, how bright an object appears to an observer. Apparent brightness depends on both the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Normae
μ Normae, Latinised as Mu Normae, is a blue supergiant star of spectral type O9.7 Iab, located in the constellation of Norma. It shines as bright as 339,000 suns and is weighs 40 solar masses. It varies in visual magnitude between 4.87 and 4.98, and is suspected of being an Alpha Cygni variable, which are named after Deneb. It is in the same direction and at the same distance as the faint open cluster NGC 6169, although it is brighter than the combined magnitude of all the other stars in the cluster. It was considered the prototype of the μ Normae class of open clusters by Collinder. References External links Jim Kaler's stars - Mu Normae {{DEFAULTSORT:Mu Normae O-type supergiants Norma (constellation) Alpha Cygni variables Normae, Mu 6155 081122 149038 Durchmusterung objects Runaway stars ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer. The word ''magnitude'' in astronomy, unless stated otherwise, usually refers to a celestial object's apparent magnitude. The magnitude scale dates back to the ancient Roman astronomer Claudius Ptolemy, whose star catalog listed stars from 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined in a way to closely match this historical system. The scale is reverse logarithmic: the brighter an object is, the lower its magnitude number. A difference of 1.0 in magnitude corresponds to a brightness ratio of \sqrt /math>, or about 2.512. For example, a star of magnitude 2.0 is 2.512 times as bright as a star of magnitude 3.0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
88 Modern Constellations
In contemporary astronomy, 88 constellations are recognized by the International Astronomical Union (IAU). Each constellation is a region of the celestial sphere, sky, bordered by arcs of right ascension and declination. Together they cover the celestial sphere, with their boundaries adopted officially by the International Astronomical Union in 1928 and published in 1930. The ancient Sumerians, and later the Greek astronomy, Greeks (as recorded by Ptolemy), established most of the northern constellations in international use today. The constellations along the ecliptic are called the zodiac. When explorers mapped the stars of the southern skies, European astronomers proposed new constellations for that region, as well as ones to fill gaps between the traditional constellations. In 1922, the International Astronomical Union adopted three-letter abbreviations for 89 constellations, the modern list of 88 plus Argo Navis, Argo. After this, Eugène Joseph Delporte drew up boundarie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirit Level
A spirit level, bubble level, or simply a level, is an instrument designed to indicate whether a surface is horizontal (level) or vertical ( plumb). Different types of spirit levels may be used by carpenters, stonemasons, bricklayers, other building trades workers, surveyors, millwrights and other metalworkers, and in some photographic or videographic work. Construction Early tubular spirit levels had very slightly curved glass vials with constant inner diameter at each viewing point. These vials are incompletely filled with a liquid, usually a colored spirit or alcohol, leaving a bubble in the tube. They have a slight upward curve, so that the bubble naturally rests in the center, the highest point. At slight inclinations the bubble travels away from the marked center position. Where a spirit level must also be usable upside-down or on its side, the curved constant-diameter tube is replaced by an uncurved barrel-shaped tube with a slightly larger diameter in its mid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
