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Grand Design Spiral Galaxy
A grand design spiral galaxy is a spiral galaxy with prominent and well-defined continuous spiral arms, as opposed to multi-arm, patchy and flocculent spirals which have subtler structural features. The spiral arms of a grand design galaxy extend clearly around the galaxy, covering a significant portion of the galaxy's circumference. Theses spiral arms host lot of star formation making them home to an abundance of bright, hot and short lived massive stars. As of 2002, approximately 10 percent of all currently known spiral galaxies are classified as grand design type spirals, including M51 (Whirlpool Galaxy), M74 (Phantom Galaxy), M81 (Bode’s Galaxy), M83 (Southern pinwheel galaxy), M101 (Pinwheel Galaxy), NGC 6946 (Firworks Galaxy) and IC 342 (The Hidden Galaxy). Origin of structure Density wave theory is the preferred explanation for the well-defined structure of grand design spirals, first suggested by Chia-Chiao Lin and Frank Shu in 1964. The term "grand design" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grand Design Galaxy
Grand may refer to: People with the name * Grand (surname) * Grand L. Bush (born 1955), American actor Places * Grand, Oklahoma, USA * Grand, Vosges, village and commune in France with Gallo-Roman amphitheatre * Grand County (other), several places * Grand Geyser, Upper Geyser Basin of Yellowstone, USA * Le Grand, California, USA; census-designated place * Mount Grand, Brockville, New Zealand Arts, entertainment, and media * ''Grand'' (Erin McKeown album), 2003 * "Grand" (Kane Brown song), 2022 * ''Grand'' (Matt and Kim album), 2009 * ''Grand'' (magazine), a lifestyle magazine related to related to grandparents * ''Grand'' (TV series), American sitcom, 1990 * Grand Production, Serbian record label company Other uses * Great Recycling and Northern Development Canal, also known as GRAND Canal * Grand (slang), one thousand units of currency * Giant Radio Array for Neutrino Detection, also known as GRAND See also * * * Grand Hotel (other) * Grand stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinwheel Galaxy
The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on, counterclockwise intermediate spiral galaxy located from Earth in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 and was communicated that year to Charles Messier, who verified its position for inclusion in the '' Messier Catalogue'' as one of its final entries. On February 28, 2006, NASA and the European Space Agency released a very detailed image of the Pinwheel Galaxy, which was the largest and most detailed image of a galaxy by Hubble Space Telescope at the time. The image was composed of 51 individual exposures, plus some extra ground-based photos. Discovery Pierre Méchain, the discoverer of the galaxy, described it as a "nebula without star, very obscure and pretty large, 6' to 7' in diameter, between the left hand of Bootes and the tail of the great Bear. It is difficult to distinguish when one illuminates the ratingwires." William Herschel wrote in 1784 tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Formation
Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function. Most stars do not form in isolation but as part of a group of stars referred as star clusters or stellar associations. First stars Star formation is divided into three groups called "Populations". Population III stars formed from primordial hydrogen after the Big Bang. These stars are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frank Shu
Frank Hsia-San Shu (; June 2, 1943 – April 22, 2023) was a Chinese-American astrophysicist, astronomer, and author. He served as a Professor Emeritus at the University of California, Berkeley and University of California, San Diego. He is best known for proposing the density wave theory to explain the structure of spiral galaxies, and for describing a model of star formation, where a giant dense molecular cloud collapses to form a star. Early life and education Shu's hometown is Wenzhou, Zhejiang, but he was born in Kunming, Yunnan, in 1943. His father, Shu Shien-Siu, was a mathematician and an instructor at the National Tsing Hua University, which, at that time due to World War II, was temporarily relocated to Kunming from Beijing. The senior Shu would serve as the President of the National Tsing Hua University from 1970 to 1975. When Shu was two months old, his father went to the United States for study and, later, work. Shu and his family went to Taiwan through Hong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chia-Chiao Lin
Chia-Chiao Lin (; 7 July 1916 – 13 January 2013) was a Chinese-born American applied mathematician and Institute Professor at the Massachusetts Institute of Technology. Lin made major contributions to the theory of hydrodynamic stability, turbulent flow, mathematics, and astrophysics. Biography Lin was born in Beijing with ancestral roots in Fuzhou. In 1937 Lin graduated from the department of physics, National Tsinghua University in Beijing. After graduation he was a teaching assistant in the Tsinghua University physics department. In 1939 Lin won a Boxer Indemnity Scholarship and was initially supported to study in the United Kingdom. However, due to World War II, Lin and several others were sent to North America by ship. Unluckily, Lin's ship was stopped in Kobe, Japan, and all students had to return to China. In 1940, Lin finally reached Canada and studied at the University of Toronto from which he earned his M.Sc. In 1941. Lin continued his studies in the Unite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density Wave Theory
Density wave theory or the Lin–Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies. The Lin–Shu theory introduces the idea of long-lived quasistatic spiral structure (QSSS hypothesis). In this hypothesis, the spiral pattern rotates with a particular angular frequency (pattern speed), whereas the stars in the galactic disk orbit at varying speeds, which depend on their distance to the galaxy center. The presence of spiral density waves in galaxies has implications on star formation, since the gas orbiting around the galaxy may be compressed and cause shock waves periodically. Theoretically, the formation of a global spiral pattern is treated as an instability of the stellar disk caused by the self-gravity, as opposed to tidal interactions. The mathematical formulation of the theory has also been extended to other astrophysical disk systems, such as Saturn's rings. Galactic spiral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IC 342
IC 342 (also known as Caldwell 5) is an intermediate spiral galaxy in the constellation Camelopardalis, located relatively close to the Milky Way. Despite its size and actual brightness, its location behind dusty areas near the galactic equator makes it difficult to observe, leading to the nickname "The Hidden Galaxy", though it can readily be detected even with binoculars. If the galaxy were not obscured, it would be visible by naked eye. The dust makes it difficult to determine its precise distance; modern estimates range from about 7 million light-years (Mly) to about 11 Mly. The galaxy was discovered by William Frederick Denning in 1892. It is one of the brightest in the IC 342/Maffei Group, one of the closest galaxy groups to the Local Group. Edwin Hubble first thought it to be in the Local Group, but it was later determined not to be a member. In 1935, Harlow Shapley found that it was wider than the full moon, and by angular size the third-largest spiral galaxy then kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 6946
NGC 6946, sometimes referred to as the Fireworks Galaxy, is a grand design, face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 (NGC 5457) in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster. The galaxy was discovered by William Herschel on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a D25 B-band isophotal diameter of . It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way. Due to its prodigious sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messier 83
Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation borders of Hydra (constellation), Hydra and Centaurus. Nicolas-Louis de Lacaille discovered M83 on 17 February 1752 at the Cape of Good Hope. Charles Messier added it to his catalogue of nebulous objects (now known as the Messier object, Messier Catalogue) in March 1781. It is one of the closest and brightest barred spiral galaxies in the sky, and is visible with binoculars. It has an Galaxy#Isophotal diameter, isophotal diameter at about . Its nickname of the Southern Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101). Characteristics M83 is a massive, grand design spiral galaxy. Its Galaxy morphological classification, morphological classification in the De Vaucouleurs system is SAB(s)c, where the 'SAB' denotes a weak-barred spiral, '(s)' indicates a pure spiral structure with no ring, and 'c' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiral Galaxy
Spiral galaxies form a galaxy morphological classification, class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''Alt URL pp. 124–151) and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating Disc (galaxy), disk containing stars, Interstellar medium, gas and dust, and a central concentration of stars known as the Bulge (astronomy), bulge. These are often surrounded by a much fainter Galactic halo, halo of stars, many of which reside in globular clusters. Spiral galaxies are named by their spiral structures that extend from the center into the galactic disc. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disc because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messier 81
Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a grand design spiral galaxy about 1 E22 m, 12 million light-years away in the constellation Ursa Major. It has a Galaxy#Isophotal diameter, D25 isophotal diameter of . Because of its relative proximity to the Milky Way galaxy, large size, and active galactic nucleus (which harbors a 70 million supermassive black hole), Messier 81 has been studied extensively by professional astronomers. The galaxy's large size and relatively high brightness also makes it a popular target for Amateur astronomy, amateur astronomers. In late February 2022, astronomers reported that M81 may be the source of Fast radio burst#FRB_20200120E, FRB 20200120E, a repeating fast radio burst. Discovery Messier 81 was first discovered by Johann Elert Bode on 31 December 1774. Thus, it is sometimes referred to as "Bode's Galaxy". In 1779, Pierre Méchain and Charles Messier reidentified Bode's object, hence listed it in the Messier object, Messie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messier 74
Messier 74 (also known as NGC 628 and Phantom Galaxy) is a large spiral galaxy in the equatorial constellation Pisces. It is about 32 million light-years away from Earth. The galaxy contains two clearly defined spiral arms and is therefore used as an archetypal example of a grand design spiral galaxy. The galaxy's low surface brightness makes it the most difficult Messier object for amateur astronomers to observe. Its relatively large angular (that is, apparent) size and the galaxy's face-on orientation make it an ideal object for professional astronomers who want to study spiral arm structure and spiral density waves. It is estimated that M74 hosts about 100 billion stars. Observation history M74 was discovered by Pierre Méchain in 1780. He then communicated his discovery to Charles Messier, who listed the galaxy in his catalog. In July 2022, it was observed by the James Webb Space Telescope. Structure M74 has two spiral arms that wind counterclockwise from the galaxy' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
