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Field Galaxies .
A field galaxy is a galaxy that does not belong to a larger galaxy group or cluster and hence is gravitationally alone. Roughly 80% of all galaxies located within of the Milky Way are in groups or clusters of galaxies. Most low-surface-brightness galaxies are field galaxies."An Introduction to Galaxies and Cosmology", ''David J. Adams and others'' The median Hubble-type of field galaxies is Sb, a type of 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'' List of field galaxies A list of nearby relatively bright field galaxies within the Local Volume, about ...
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Galaxy
A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarf galaxy, dwarfs with less than a thousand stars, to the List of largest galaxies, largest galaxies known – Type-cD galaxy, supergiants with one hundred 10^12, trillion stars, each orbiting its galaxy's centre of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few per cent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorised according to their visual morphology (astronomy), morphology as elliptical galaxy, elliptical, Spiral galaxy, spiral, or irregular galaxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andromeda (constellation)
Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux. Its brightest star, Alpheratz (Alpha Andromedae), is a binary star that has also been counted as a part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 4136
NGC4136 is a barred spiral galaxy in the constellation of Coma Berenices. Its velocity with respect to the cosmic microwave background is , which corresponds to a Hubble distance of . Additionally, seven ''non-redshift'' measurements give a distance of . It was discovered by German-British astronomer William Herschel on 13 March 1785. Morphology Eskridge, Frogel, and Pogge published a paper in 2002 describing the morphology of 205 closely spaced spiral or lenticular galaxies. The observations were made in the H-band of the infrared and in the B-band (blue). Eskridge and colleagues described NGC 4136 as follows: NGC 4274 Group NGC 4136 is a member of the NGC 4274 group (also known as LGG 279) which has at least 19 galaxies, including NGC 4020, NGC 4062, NGC 4173, NGC 4203, NGC 4245, NGC 4251, NGC 4274, NGC 4278, NGC 4283, NGC 4310, NGC 4314, NGC 4359, NGC 4414, NGC 4509, NGC 4525, UGC 7300, and MCG+05-29-066. Supernova One supernova has been observed in NGC 4136 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees, and also the longest at over 100 degrees. Its southern end borders Libra (constellation), Libra and Centaurus (constellation), Centaurus and its northern end borders Cancer (constellation), Cancer. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy. Commonly represented as a water snake (other), water snake, it straddles the celestial equator. History and mythology Western mythology The Greek constellation of Hydra is an adaptation of a Babylonian astronomy, Babylonian constellation: the MUL.APIN includes a "serpent" constellation (MUL.DINGIR.MUŠ) that loosely corresponds to Hydra. It is one of two Babylonian "serpent" constellations (the other being the origin of the Greek Serpens), a mythological hybrid of serpent, lion and bird. The shape of Hydra resembles a twisting snake, and features as such in some Greek myths. One myth associates it w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 3621
NGC 3621 is a Disc galaxy, disk spiral galaxy about away in the equatorial constellation of Hydra (constellation), Hydra. It was discovered by German-British astronomer William Herschel on 17 February 1790. NGC 3621 is comparatively bright and can be well seen in moderate-sized telescopes. The galaxy is around across and is inclined at an angle of 66° from being viewed face on. It shines with a luminosity equal to 13 billion times solar luminosity, that of the Sun. The Galaxy morphological classification, morphological classification is SA(s)d, which indicates this is an ordinary spiral with loosely wound arms. There is no evidence for a Bulge (astronomy), bulge. Although it appears to be isolated, NGC 3621 belongs to the Leo spur. This galaxy has an active galactic nucleus, active nucleus that matches a Seyfert galaxy, Seyfert 2 optical spectrum, suggesting that a low mass supermassive black hole is present at the core. Based upon the motion of stars in the nucleus, this obj ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sextans (constellation)
Sextans is a faint, minor constellation on the celestial equator which was introduced in 1687 by Polish people, Polish astronomer Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his observations. Characteristics Sextans is a medium sized constellation bordering Leo (constellation), Leo to the north, touching on Hydra (constellation), Hydra to the southwest, and Crater (constellation), Crater to the southeast. The recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Sex". The official constellation boundaries, as set by Belgian astronomer Eugène Joseph Delporte, Eugène Delporte in 1930, are defined by a square. In the equatorial coordinate system, the right ascension coordinates of these borders lie between and , while the declination coordinates are between +6.43° and −11.7°. Since it is close to the ecliptic plane, the Moon and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 3115
NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it is several times bigger than the Milky Way. It is a lenticular (S0) galaxy because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar. One supernova has been observed in NGC 3115: SN 1935B (type and mag. unknown). Star formation NGC 3115 has consumed most of the gas of its youthful accretion disk. It has very little gas and dust left that would trigger new star formation. The vast majority of its component stars are very old. Black hole In 1992 John Kormendy of the University of Hawaii and Douglas Richstone of the University of Michigan an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leo (constellation)
Leo is one of the constellations of the zodiac, between Cancer (constellation), Cancer the crab to the west and Virgo (constellation), Virgo the maiden to the east. It is located in the Northern celestial hemisphere. Its name is Latin for lion, and to the ancient Greeks represented the Nemean Lion killed by the mythical Greek hero Heracles as one of his Twelve Labours, twelve labors. Its old astronomical symbol is (♌︎). One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Leo remains one of the 88 modern constellations today, and one of the most easily recognizable due to its many bright stars and a distinctive shape that is reminiscent of the crouching lion it depicts. Features Stars Leo contains many bright stars, many of which were individually identified by the ancients. There are nine bright stars that can be easily seen with the naked eye, four of the nine stars are either first or second magnitude which render this constellation especially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 2903
NGC 2903 is an isolated barred spiral galaxy in the equatorial constellation of Leo, positioned about 1.5° due south of Lambda Leonis. It was discovered by German-born astronomer William Herschel, who cataloged it on November 16, 1784. He mistook it as a double nebula, as did subsequent observers, and it wasn't until the nineteenth century that the Third Earl of Rosse resolved into a spiral form. J. L. E. Dreyer assigned it the identifiers 2903 and 2905 in his ''New General Catalogue''; NGC 2905 now designates a luminous knot in the northeastern spiral arm. This field galaxy is located about 30 million light-years away from the Milky Way, and is a member of the Virgo Supercluster. The morphological classification of this galaxy is SBbc, indicating a barred spiral (SB) with moderate to tightly-wound spiral arms (bc). De Vaucouleurs and associates assigned it the class SAB(rs)bc, suggesting a weaker bar structure (SAB) with a partial ring (rs). The bar structure appears ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lynx (constellation)
Lynx is a constellation named after lynx, the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomy, amateur astronomers. Six star systems have been found to contain exoplanet, planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler spectroscopy, Doppler method; those of XO-2 (star), XO-2, XO-4, XO-5 and WASP-13 were observed as they Methods of detecting extrasolar planets#Transit method, passed in front of the host star. Within the constellation's borders lie NGC 2419, an unusually remote globular cluster; the galaxy NGC 2770, which has hosted three recent Type Ib and Ic supernovae, Type Ib supernovae; the distant quasar APM 08279+5255, whose light is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 2683
NGC 2683 is a field spiral galaxy in the northern constellation of Lynx. It was nicknamed the "UFO Galaxy" by the Astronaut Memorial Planetarium and Observatory. It was discovered by the astronomer William Herschel on February 5, 1788. It is viewed nearly edge-on from Earth's location in space and is located about 30 million light-years away, although previous estimates also give distances between 16 and 25 million light-years. NGC 2683 is receding from Earth at , and from the Galactic Center at . Visibility The reddened light from the center of the galaxy appears yellowish due to the intervening gas and dust located within the outer arms of NGC 2683. Its apparent magnitude is 10.6 making it not visible to the human eye without the aid of a small telescope. Characteristics While usually considered an unbarred spiral galaxy, recent research suggests it may in fact be a barred spiral galaxy; its bar is hard to see due to its high inclination. Further support for the presence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columba (constellation)
Columba is a faint constellation designated in the late sixteenth century, remaining in official use, with its rigid limits set in the 20th century. Its name is Latin for dove. It takes up 1.31% of the southern celestial hemisphere and is just south of Canis Major and Lepus. History * Early 3rd century BC: Aratus's astronomical poem ''Phainomena'' (lines 367–370 and 384–385) mentions faint stars where Columba is now but does not fit any name or figure to them. * 2nd century AD: Ptolemy lists 48 constellations in the '' Almagest''. While Columba is not yet among them, several stars south of Canis Major listed in this work will eventually become part of Columba. * c. 150–215 AD: Clement of Alexandria wrote in his ''Logos Paidogogos''"Αἱ δὲ σφραγῖδες ἡμῖν ἔστων πελειὰς ἢ ἰχθὺς ἢ ναῦς οὐριοδρομοῦσα ἢ λύρα μουσική, ᾗ κέχρηται Πολυκράτης, ἢ ἄγκυρα ναυτική," (= " h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
