Aix-Marseille University
Aix-Marseille University is a public research university located in the region of Provence, southern France. It was founded in 1409 when Louis II of Anjou, Count of Provence, petitioned the Pisan Antipope Alexander V to establish the University of Provence; the university as it is today was formed by the merger of the University of Provence, the University of the Mediterranean and Paul Cézanne University. The merger became effective on 1 January 2012, resulting in the creation of the largest university in the French-speaking world, with about 74,000 students. AMU has the largest budget of any academic institution in the Francophone world, standing at €750 million; the university is organized around five main campuses situated in Marseille. Apart from its major campuses, AMU owns and operates facilities in Arles, Avignon, Digne-les-Bains, Gap, La Ciotat and Salon-de-Provence; the university is headquartered at the Marseille. AMU has produced many notable alumni in the fields of law, business, science and arts.
To date, there have been four Nobel Prize laureates amongst its alumni and faculty, as well as a two-time recipient of the Pulitzer Prize, four César Award winners, multiple heads of state or government, parliamentary speakers, government ministers and members of the constituent academies of the Institut de France. AMU has hundreds of research and teaching partnerships, including close collaboration with the French National Centre for Scientific Research and the French Alternative Energies and Atomic Energy Commission. AMU is a member of numerous academic organisations including the European University Association and the Mediterranean Universities Union; the institution developed out of the original University of Provence, founded on 9 December 1409 as a Studium generale by Louis II of Anjou, Count of Provence, recognized by papal bull issued by the Pisan Antipope Alexander V. However, there is evidence that teaching in Aix existed in some form from the beginning of the 12th century, since there were a doctor of theology in 1100, a doctor of law in 1200 and a professor of law in 1320 on the books.
The decision to establish the university was, in part, a response to the already-thriving University of Paris. As a result, in order to be sure of the viability of the new institution, Louis II compelled his Provençal students to study in Aix only. Thus, the letters patent for the university were granted, the government of the university was created; the Archbishop of Aix-en-Provence, Thomas de Puppio, was appointed as the first chancellor of the university for the rest of his life. After his death in 1420, a new chancellor was elected by the rector and licentiates – an uncommon arrangement not repeated at any other French university; the rector had to be an “ordinary student”, who had unrestricted civil and criminal jurisdiction in all cases where one party was a doctor or scholar of the university. Those displeased with the rector's decisions could appeal to a doctor legens. Eleven consiliarii provided assistance to the rector; these individuals represented all were elected from among the students.
The constitution was of a student-university, the instructors did not have great authority except in granting degrees. Mention should be made that a resident doctor or student who married was required to pay charivari to the university, the amount varying with the degree or status of the man, being increased if the bride was a widow. Refusal to submit to this statutable extortion was punished by the assemblage of students at the summons of the rector with frying-pans and horns at the house of the newly married couple. Continued recusancy was followed by the piling up of dirt in front of their door upon every Feast-day; these injunctions were justified on the ground that the money extorted was devoted to divine service. In 1486 Provence passed to the French crown; the university's continued existence was approved by Louis XII of France, Aix-en-Provence continued to be a significant provincial centre. It was, for instance, the seat of the Parliament of Aix-en-Provence from 1501 to 1789, no doubt aided by the presence of the law school.
In 1603 Henry IV of France established the Collège Royal de Bourbon in Aix-en-Provence for the study of belles-lettres and philosophy, supplementing the traditional faculties of the university, but not formally a part of it. This college de plain exercice became a significant seat of learning, under the control of the Jesuit order. Throughout the 16th and 17th centuries, the college served as a preparatory, but unaffiliated, school for the university. Only the university was entitled to award degrees in the theology and medicine. Universities accepted candidates who had studied in colleges formally affiliated with them, which in reality required both college and university to be situated in the same city. In 1762 the Jesuits were forced to leave France, in 1763 the Collège Royal de Bourbon was affiliated with the university as a faculty of arts; the addition of the Collège Royal de Bourbon widened the scope of courses provided at the University of Provence. Formal instruction in French was provided at the college, with texts and a structured course of study.
Subsequently, physics became a part of the curriculum at the college as a part of the philosophy course in the 18th century. Equipment for carrying out experiments was obtained and the first course in experimental physics was provided at Aix-e
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum; such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
Cosmology
Cosmology is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future. It is the scientific study of the origin and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics, its ultimate fate, as well as the laws of science that govern these areas; the term cosmology was first used in English in 1656 in Thomas Blount's Glossographia, in 1731 taken up in Latin by German philosopher Christian Wolff, in Cosmologia Generalis. Religious or mythological cosmology is a body of beliefs based on mythological and esoteric literature and traditions of creation myths and eschatology. Physical cosmology is studied by scientists, such as astronomers and physicists, as well as philosophers, such as metaphysicians, philosophers of physics, philosophers of space and time; because of this shared scope with philosophy, theories in physical cosmology may include both scientific and non-scientific propositions, may depend upon assumptions that cannot be tested.
Cosmology differs from astronomy in that the former is concerned with the Universe as a whole while the latter deals with individual celestial objects. Modern physical cosmology is dominated by the Big Bang theory, which attempts to bring together observational astronomy and particle physics. Theoretical astrophysicist David N. Spergel has described cosmology as a "historical science" because "when we look out in space, we look back in time" due to the finite nature of the speed of light. Physics and astrophysics have played a central role in shaping the understanding of the universe through scientific observation and experiment. Physical cosmology was shaped through both mathematics and observation in an analysis of the whole universe; the universe is understood to have begun with the Big Bang, followed instantaneously by cosmic inflation. Cosmogony studies the origin of the Universe, cosmography maps the features of the Universe. In Diderot's Encyclopédie, cosmology is broken down into uranology, aerology and hydrology.
Metaphysical cosmology has been described as the placing of humans in the universe in relationship to all other entities. This is exemplified by Marcus Aurelius's observation that a man's place in that relationship: "He who does not know what the world is does not know where he is, he who does not know for what purpose the world exists, does not know who he is, nor what the world is." Physical cosmology is the branch of physics and astrophysics that deals with the study of the physical origins and evolution of the Universe. It includes the study of the nature of the Universe on a large scale. In its earliest form, it was, the study of the heavens. Greek philosophers Aristarchus of Samos and Ptolemy proposed different cosmological theories; the geocentric Ptolemaic system was the prevailing theory until the 16th century when Nicolaus Copernicus, subsequently Johannes Kepler and Galileo Galilei, proposed a heliocentric system. This is one of the most famous examples of epistemological rupture in physical cosmology.
Isaac Newton's Principia Mathematica, published in 1687, was the first description of the law of universal gravitation. It provided a physical mechanism for Kepler's laws and allowed the anomalies in previous systems, caused by gravitational interaction between the planets, to be resolved. A fundamental difference between Newton's cosmology and those preceding it was the Copernican principle—that the bodies on earth obey the same physical laws as all the celestial bodies; this was a crucial philosophical advance in physical cosmology. Modern scientific cosmology is considered to have begun in 1917 with Albert Einstein's publication of his final modification of general relativity in the paper "Cosmological Considerations of the General Theory of Relativity". General relativity prompted cosmogonists such as Willem de Sitter, Karl Schwarzschild, Arthur Eddington to explore its astronomical ramifications, which enhanced the ability of astronomers to study distant objects. Physicists unchanging. In 1922 Alexander Friedmann introduced the idea of an expanding universe that contained moving matter.
Around the same time the Great Debate took place, with early cosmologists such as Heber Curtis and Ernst Öpik determining that some nebulae seen in telescopes were separate galaxies far distant from our own. In parallel to this dynamic approach to cosmology, one long-standing debate about the structure of the cosmos was coming to a climax. Mount Wilson astronomer Harlow Shapley championed the model of a cosmos made up of the Milky Way star system only; this difference of ideas came to a climax with the organization of the Great Debate on 26 April 1920 at the meeting of the U. S. National Academy of Sciences in Washington, D. C; the debate was resolved when Edwin Hubble detected Cepheid Variables in the Andromeda galaxy in 1923 and 1924. Their distance established spiral nebulae well beyond the edge of the Milky Way. S
Exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first evidence of an exoplanet was not recognized as such; the first scientific detection of an exoplanet was in 1988. The first confirmed detection occurred in 1992; as of 1 April 2019, there are 4,023 confirmed planets in 3,005 systems, with 656 systems having more than one planet. There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like stars have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included; the least massive planet known is Draugr, about twice the mass of the Moon.
The most massive planet listed on the NASA Exoplanet Archive is HR 2562 b, about 30 times the mass of Jupiter, although according to some definitions of a planet, it is too massive to be a planet and may be a brown dwarf instead. There are planets that are so near to their star that they take only a few hours to orbit and there are others so far away that they take thousands of years to orbit; some are so far out. All of the planets detected so far are within the Milky Way. Nonetheless, evidence suggests that extragalactic planets, exoplanets farther away in galaxies beyond the local Milky Way galaxy, may exist; the nearest exoplanet is Proxima Centauri b, located 4.2 light-years from Earth and orbiting Proxima Centauri, the closest star to the Sun. The discovery of exoplanets has intensified interest in the search for extraterrestrial life. There is special interest in planets that orbit in a star's habitable zone, where it is possible for liquid water, a prerequisite for life on Earth, to exist on the surface.
The study of planetary habitability considers a wide range of other factors in determining the suitability of a planet for hosting life. Besides exoplanets, there are rogue planets, which do not orbit any star; these tend to be considered as a separate category if they are gas giants, in which case they are counted as sub-brown dwarfs, like WISE 0855−0714. The rogue planets in the Milky Way number in the billions; the convention for designating exoplanets is an extension of the system used for designating multiple-star systems as adopted by the International Astronomical Union. For exoplanets orbiting a single star, the designation is formed by taking the name or, more designation of its parent star and adding a lower case letter; the first planet discovered in a system is given the designation "b" and planets are given subsequent letters. If several planets in the same system are discovered at the same time, the closest one to the star gets the next letter, followed by the other planets in order of orbital size.
A provisional IAU-sanctioned standard exists to accommodate the designation of circumbinary planets. A limited number of exoplanets have IAU-sanctioned proper names. Other naming systems exist. For centuries scientists and science fiction writers suspected that extrasolar planets existed, but there was no way of detecting them or of knowing their frequency or how similar they might be to the planets of the Solar System. Various detection claims made in the nineteenth century were rejected by astronomers; the first evidence of an exoplanet was not recognized as such. The first suspected scientific detection of an exoplanet occurred in 1988. Shortly afterwards, the first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12; the first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method.
In February 2018, researchers using the Chandra X-ray Observatory, combined with a planet detection technique called microlensing, found evidence of planets in a distant galaxy, stating "Some of these exoplanets are as small as the moon, while others are as massive as Jupiter. Unlike Earth, most of the exoplanets are not bound to stars, so they're wandering through space or loosely orbiting between stars. We can estimate. In the sixteenth century the Italian philosopher Giordano Bruno, an early supporter of the Copernican theory that Earth and other planets orbit the Sun, put forward the view that the fixed stars are similar to the Sun and are accompanied by planets. In the eighteenth century the same possibility was mentioned by Isaac Newton in the "General Scholium" that concludes his Principia. Making a comparison to the Sun's planets, he wrote "And if the fixed stars are the centres of similar systems, they will all be constructed according to a similar design and subject to the dominion of One."In 1952, more than 40 years before the first hot Jupiter was discovere
France
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
Stephan's Quintet
Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group discovered. The group, visible in the constellation Pegasus, was discovered by Édouard Stephan in 1877 at the Marseille Observatory; the group is the most studied of all the compact galaxy groups. The brightest member of the visual grouping is NGC 7320, shown to have extensive H II regions, identified as red blobs, where active star formation is occurring. Four of the five galaxies in Stephan's Quintet form a physical association, Hickson Compact Group 92, will merge with each other. Radio observations in the early 1970s revealed a mysterious filament of emission which lies in inter-galactic space between the galaxies in the group; this same region is detected in the faint glow of ionized atomic hydrogen seen in the visible part of the spectrum as a green arc. Two space telescopes have provided new insight into the nature of the filament, now believed to be a giant intergalactic shock-wave caused by one galaxy falling into the center of the group at several millions of kilometers per hour.
As NGC 7318B collides with gas in the group, a huge shock wave bigger than the Milky Way spreads throughout the medium between the galaxies, heating some of the gas to temperatures of millions of degrees where they emit X-rays detectable with the NASA Chandra X-ray Observatory. The NASA Spitzer Space Telescope, which detects infrared radiation, discovered a powerful molecular hydrogen signal from the shock wave between the galaxies; this emission is one of the most turbulent formations of molecular hydrogen seen, the strongest emission originates near the center of the green area in the visible light picture discussed earlier. This phenomenon was discovered by an international team led by scientists at the California Institute of Technology and including scientists from Australia and China; the detection of molecular hydrogen from the collision was unexpected because the hydrogen molecule is fragile and is destroyed in shock waves of the kind expected in Stephan's Quintet. However, one solution is that when a shock front moves through a cloudy medium like the center of the group, millions of smaller shocks are produced in a turbulent layer, this can allow molecular hydrogen to survive.
NGC 7320 indicates a small redshift while the other four exhibit large redshifts. Since galactic redshift is proportional to distance, NGC 7320 is only a foreground projection and is ~39 million lightyears from Earth versus the 210-340 million lightyears of the other four. NGC 7319 has a type 2 Seyfert nucleus. A sixth galaxy, NGC 7320C belongs to the Hickson association: it has a redshift similar to the Hickson galaxies, a tidal tail appears to connect it with NGC 7319. Seyfert's Sextet Robert's Quartet NGC 7331 Group A Shocking Surprise in Stephan's Quintet. 2 March 2006. 10 March 2006 NASA/JPL-Caltech/Max-Planck Institute/P. Appleton article P. N. Appleton, K. C. Xu, W. Reach, M. A. Dopita, Y. Gao, N. Lu, C. C. Popescu, J. W. Sulentic, R. J. Tuffs, M. S. Yun. Powerful High-Velocity Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet, The Astrophysical Journal, 639:L51-L54, 3 March 2006. 10 March 2006 Gigantic cosmic cataclysm in Stephan's Quintet of galaxies Stephan's Quintet.
10 March 2006 University of Alabama Astronomy Stephan's Quintet: Intruder Galaxy Shocks Tightly-Knit Group. 8 May 03. 10 March 2006 Chandra X-Ray Observatory Stephan's Quintet and description from the National Optical Astronomy Observatory. Links to a labeled locator photo. GALEX: Stephan's Quintet and NGC 7331 Star Clusters Born in the Wreckage of Cosmic Collisions News Release at ESA/Hubble Stephan's Quintet NightSkyInfo.com: Stephan's Quintet What's Behind Stephan's Quintet? Peter Edmonds, Chandra Blog, 21 July 2009 Astronomy Picture of the Day on Stephan's Quintet: 13 Nov 2000 12 Aug 2003 11 Sep 2009 Stephan's Quintet on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Sky Map and images
Édouard Stephan
Édouard Jean-Marie Stephan was a French astronomer. His surname is sometimes spelled Stéphan in some literature, but this is erroneous, he was born in Sainte Pezenne and attended the Ecole Normale Superieure, graduated at the top of his class in 1862. He was the director of the Marseille Observatory from 1864 to 1907. In the early part of his career there, he had limited opportunities to do observations because he was preoccupied with improving the observatory, he discovered the asteroid 89 Julia in 1866. In 1867 he used the new telescope to observe a transit of Mercury. Between 1870 and 1875, Stephan systematically studied nebulae recording their positions and discovering many new ones, his goal was to enable the exact measurement of stellar proper motions by creating a reference system of fixed objects. In 1873, Stephan was the first person to attempt to measure the angular diameter of a star using interferometry, converting the 80 cm telescope at Marseille Observatory into an interferometer.
He did this by obscuring the reflector with a mask containing two vertical slits. The star he chose to perform this experiment was Sirius, he did not succeed in resolving any stellar disks, but by 1874 had obtained an upper limit to stellar diameters of 0.158". In 1881 he discovered NGC 5, he discovered the galaxy NGC 6027 the following year using the 80 cm reflector. Among others, he discovered Stephan's Quintet known as "Arp 319", a group of five galaxies. Stephan made this discovery with the first telescope equipped with a reflection coated mirror. In 1884 the French Academy of Sciences awarded him the Valz Prize, his name is associated with the periodic comet 38P/Stephan-Oterma, although Jérôme Coggia saw it first. He became a Chevalier of the Légion d'honneur in 1868 and an Officier of the Légion d'honneur in 1879. JO 7 9
