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Stephenson 2-18
Stephenson 2-18 (abbreviated to St2-18), also known as Stephenson 2 DFK 1 or RSGC2-18, is an enigmatic red supergiant (RSG) or possible extreme red hypergiant (RHG) star in the constellation of Scutum. It lies near the open cluster Stephenson 2, which is located about away from Earth in the Scutum–Centaurus Arm of the Milky Way galaxy, and is assumed to be one of a group of stars at a similar distance, although some sources consider it to be an unrelated or foreground red supergiant. It is among the largest known stars, one of the most luminous red supergiants, and one of the most luminous stars in the Milky Way. Stephenson 2-18 has an estimated radius of around , which would correspond to a volume nearly 10 billion times that of the Sun. Taking this estimate as correct, it would take nearly 9 hours to travel around its surface at the speed of light, compared to 14.5 seconds for the Sun. If placed at the center of Earth's Solar System, its photosphere would engulf th ...
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Stephenson 2-18 Zoomed In, 2MASS Survey, 2003
Stephenson is a medieval patronymic surname meaning "son of Stephen". The earliest public record is found in the county of Huntingdonshire in 1279. There are variant spellings including Stevenson. People with the surname include: *Ashley Stephenson (born 1982), Canadian hockey and baseball player *Ashley Stephenson (horticulturalist), Ashley Stephenson (1927–2021), British horticulturalist *Benjamin Stephenson (other), several people *Ben Stephenson, Anglo-American television executive *Chandler Stephenson (born 1994), Canadian ice hockey player *Charles Bruce Stephenson (1929–2001), American astronomer *D. C. Stephenson (1891–1966), American, Ku Klux Klan leader *Debra Stephenson (born 1972), British actress *Dwight Stephenson, American football player *Earl Stephenson (born 1947), American baseball pitcher *Gene Stephenson, American college baseball coach *George Stephenson (1781–1848), British mechanical engineer who created Stephenson's Rocket *George Robert S ...
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Speed Of Light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit for the speed at which conventional matter or energy (and thus any signal carrying information) can travel through space. All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and very sensitive measurements, their finite speed has noticeable effects. Starlight viewed on Earth left the stars many years ago, allowing humans to study the history of the universe by viewing distant objects. When communicating with distant space probes, it can take minutes to hours for signals to travel from Earth to the spacecraft and vice versa. In computing, the speed of light fixes ...
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Absolute Magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly , without Extinction (astronomy), extinction (or dimming) of its light due to absorption by Interstellar medium, interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. As with all astronomical magnitude (astronomy), magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified Filter (optics), filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV phot ...
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Supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K. Definition The title supergiant, as applied to a star, does not have a single concrete definition. The term ''giant star'' was first coined by Hertzsprung when it became apparent that the majority of stars fell into two distinct regions of the Hertzsprung–Russell diagram. One region contained larger and more luminous stars of spectral types A to M and received the name ''giant''. Subsequently, as they lacked any measurable parallax, it became apparent that some of these stars were significantly larger and more luminous than the bulk, and the term ''super-giant'' arose, quickly adopted as ''supergiant''. Spectral luminosity class Supergiant stars can be identified on the basis of thei ...
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M-type Star
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivided ...
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Scutum
The ''scutum'' (; plural ''scuta'') was a type of shield used among Italic peoples in antiquity, most notably by the army of ancient Rome starting about the fourth century BC. The Romans adopted it when they switched from the military formation of the hoplite phalanx of the Greeks to the formation with maniples ( la, manipuli). In the former, the soldiers carried a round shield, which the Romans called a ''clipeus''. In the latter, they used the ''scutum'', which was larger. Originally it was oblong and convex, but by the first century BC it had developed into the rectangular, semi-cylindrical shield that is popularly associated with the ''scutum'' in modern times. This was not the only kind the Romans used; Roman shields were of varying types depending on the role of the soldier who carried it. Oval, circular and rectangular shapes were used throughout Roman history. History The first depictions of the scutum are by the Este culture in the 8th century bc, and subsequently ...
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RSGC1-F01
RSGC1-F01 is a red supergiant located in the RSGC1 open cluster in the constellation of Scutum. The radius was calculated to be around 1,530 times that of the Sun (the radius is calculated by applying the Stefan-Bolzmann law), making it one of the largest stars discovered so far. This corresponds to a volume 3.58 billion times bigger than the Sun. If placed at the center of the Solar System, the photosphere would engulf the orbit of Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t .... See also * RSGC1-F02 References Scutum (constellation) M-type supergiants J18375629-0652322 TIC objects {{supergiant-star-stub ...
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Australia Telescope Compact Array
The Australia Telescope Compact Array (ATCA) is a radio telescope operated by CSIRO at the Paul Wild Observatory, twenty five kilometres (16 mi) west of the town of Narrabri in New South Wales, Australia. Its opening ceremony took place on September 2, 1988. Overview The telescope is an array of six identical diameter dishes, which commonly operate in aperture synthesis mode to produce radio images. Five of the dishes can be moved along a three-kilometre (2 mi) railway track oriented east-west. The sixth antenna is situated three kilometres west of the end of the main track. Each dish weighs about . The Compact Array is a part of the Australia Telescope National Facility network of radio telescopes. The array is frequently operated together with other CSIRO telescopes, the dish at the Parkes Observatory and a single dish at Mopra (near Coonabarabran), to form a very long baseline interferometry array. The Array welcomes visitors from the general public. The facili ...
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Proper Motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars. The components for proper motion in the equatorial coordinate system (of a given epoch, often J2000.0) are given in the direction of right ascension (''μ''α) and of declination (''μ''δ). Their combined value is computed as the ''total proper motion'' (''μ''). It has dimensions of angle per time, typically arcseconds per year or milliarcseconds per year. Knowledge of the proper motion, distance, and radial velocity allows calculations of an object's motion from our star system's frame of reference and its motion from the galactic frame of reference – that is motion in respect to the Sun, and by coordinate transformation, that in respect to the Milky Way. Introduction Over the course of centuries, stars appear t ...
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Charles Bruce Stephenson
Charles Bruce Stephenson (February 9, 1929 – December 3, 2001) was an American astronomer. He was born on a ranch in Little Rock, Arkansas, the only son of Chauncey Elvira Stephenson and Ona Richards. During his youth he made a telescope and was a winner of the Bausch & Lomb Science Award while in High School. He attended Little Rock Junior College, then transferred to the University of Chicago. After being awarded a B.S. in mathematics in 1949, he went on to study astronomy in graduate school, attaining a M.S. in 1951. From 1951 until 1953, he served as an astronomy research assistant at Dearborn Observatory. While a student at Northwestern, he met his future wife, Elizabeth Strong—the couple were married in 1952. In 1953 he joined the military in the U.S. Army Map Service Lunar Occultation Program, serving until 1955 whereupon he returned to the study of astronomy at the University of California, Berkeley. As a doctoral student, he was awarded the '' Dorothy Klumpke Robert ...
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Star Sizes Comparison Update 2021
A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its total mass is the main factor determining its evolution and eventual fate. A star shines for most of its active life due to ...
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Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive. Saturn's interior is most likely composed of a core of iron–nickel and rock (silicon and oxygen compounds). Its core is surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and finally, a gaseous outer layer. Saturn has a pale yellow hue due to ammonia crystals in its upper atmosphere. An electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but which has a magnetic moment 580 times that of Earth due to Saturn's larger size. Saturn's magnetic field strength is around one-twentieth of Jupiter's. The outer atmosphere is g ...
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