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M1-67
M1-67 is an ejecta nebula that surrounds the Wolf–Rayet star WR 124, which is about 6.4 Parsec, kpc from Earth in the constellation of Sagitta. It contains dust which is caught up in WR 124's solar wind and which absorbs much of the star's light. It was discovered by American astronomer Paul W. Merrill in 1938, at the same time that he discovered the star it surrounds. It is approximately 6 light years across, making it about 20,000 years old. Distance and characteristics A 2010 study focused on M1-67, measuring its expansion rate by using Hubble Space Telescope photographs taken 11 years apart. The expansion rate was then compared to the expansion velocity, which was calculated from the Doppler shift of its nebular emission lines, resulting in a geometric distance of d=3.35 ± 0.67kpc. NASA has confirmed that the released gas is traveling at up to 100,000 mp/h, causing turbulence, and carrying along approximately 100 billion-mile wide glowing blobs, with each blob being around ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolf–Rayet Star
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectroscopy, spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of Stellar nucleosynthesis, heavy elements, depletion of hydrogen, and strong stellar winds. The Effective temperature, surface temperatures of known Wolf–Rayet stars range from 20,000 Kelvin (unit), K to around 210,000 Kelvin (unit), K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their Stellar classification, spectral classification. Classic (or population I) Wolf–Rayet stars are Stellar evolution, evolved, massive stars that have completely lost their outer hydrogen and are nuclear fusion, fusing helium or heavier elements in the core. A subset of the population I WR stars show hydrogen lines in their spectra and are known as WNh stars; the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WR 124
WR 124 is a Wolf–Rayet star in the constellation of Sagitta surrounded by a ring nebula of expelled material known as M1-67. It is one of the fastest runaway stars in the Milky Way with a radial velocity around . It was discovered by Paul W. Merrill in 1938, identified as a high-velocity Wolf–Rayet star. It is listed in the General Catalogue of Variable Stars as QR Sagittae with a range of 0.08 magnitudes. Distance A 2010 study of WR 124 directly measured the expansion rate of the M1-67 nebula expelled from the star using Hubble Space Telescope camera images taken 11 years apart, and compared that to the expansion velocity measured by the Doppler shift of the nebular emission lines. This yielded a distance of , which is less than previous studies, and the resulting luminosity of 150,000 times the Sun () is much lower than previously calculated. The luminosity is also lower than predicted by models for a star of this spectral class. Previous studies had found di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (AU), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 AU subtended angle, subtends an angle of one arcsecond ( of a degree (angle), degree). The nearest star, Proxima Centauri, is about from the Sun: from that distance, the gap between the Earth and the Sun spans slightly less than one arcsecond. Most Naked-eye stars, stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand parsecs, and the Andromeda Galaxy at over 700,000 parsecs. The word ''parsec'' is a shortened form of ''a distance corresponding to a parallax of one second'', coined by the British astronomer Herbert Hall Turner in 1913. The unit was introduced to simplify the calculation of astronomical distances from raw observational data. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellations were likely defined in prehistory. People used them to relate stories of their beliefs, experiences, creation myth, creation, and mythology. Different cultures and countries invented their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, only to drop into obscurity. Some were limited to a single culture or nation. Naming constellations also helped astronomers and navigators identify stars more easily. Twelve (or thirteen) ancient constellations belong to the zodiac (straddling the ecliptic, which the Sun, Moon, and planets all traver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sagitta
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Although it dates to antiquity, Sagitta has no star brighter than 3rd magnitude and has the third-smallest area of any constellation. Gamma Sagittae is the constellation's brightest star, with an apparent magnitude of 3.47. It is an aging red giant star 90% as massive as the Sun that has cooled and expanded to a radius 54 times greater than it. Delta, Epsilon, Zeta, and Theta Sagittae are each multiple stars whose components can be seen in small telescopes. V Sagittae is a cataclysmic variable—a binary star system composed of a white dwarf accreting mass of a donor star that is expected to go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Wind
The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the solar wind plasma also includes a mixture of particle species found in the solar plasma: trace amounts of heavy ions and atomic nuclei of Chemical element, elements such as carbon, nitrogen, oxygen, neon, magnesium, silicon, sulfur, and iron. There are also rarer traces of some other nuclei and isotopes such as phosphorus, titanium, chromium, and nickel's isotopes 58Ni, 60Ni, and 62Ni. Superimposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over Solar coordinate systems#Heliographic, solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul W
Paul may refer to: People * Paul (given name), a given name, including a list of people * Paul (surname), a list of people * Paul the Apostle, an apostle who wrote many of the books of the New Testament * Ray Hildebrand, half of the singing duo Paul & Paula * Paul Stookey, one-third of the folk music trio Peter, Paul and Mary * Billy Paul, stage name of American soul singer Paul Williams (1934–2016) * Vinnie Paul, drummer for American Metal band Pantera * Paul Avril, pseudonym of Édouard-Henri Avril (1849–1928), French painter and commercial artist * Paul, pen name under which Walter Scott wrote ''Paul's letters to his Kinsfolk'' in 1816 * Jean Paul, pen name of Johann Paul Friedrich Richter (1763–1825), German Romantic writer Places * Paul, Cornwall, a village in the civil parish of Penzance, United Kingdom * Paul (civil parish), Cornwall, United Kingdom * Paul, Alabama, United States, an unincorporated community * Paul, Idaho, United States, a city * Paul, Nebrask ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most versatile, renowned as a vital research tool and as a public relations boon for astronomy. The Hubble Space Telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories program, Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible spectrum, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of atmosphere of Earth, Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bow Shock
In astrophysics, bow shocks are shock waves in regions where the conditions of density and pressure change dramatically due to blowing stellar wind. Bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the magnetopause. For stars, this boundary is typically the edge of the astrosphere, where the stellar wind meets the interstellar medium. Description The defining criterion of a shock wave is that the bulk velocity of the plasma drops from " supersonic" to "subsonic", where the speed of sound cs is defined by c_s^2 = \gamma p/ \rho where \gamma is the ratio of specific heats, p is the pressure, and \rho is the density of the plasma. A common complication in astrophysics is the presence of a magnetic field. For instance, the charged particl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Nebula
A bipolar nebula is a type of nebula characterized by two lobes either side of a central star. About 10–20% of planetary nebulae are bipolar. Formation Though the exact causes of this nebular structure are not known, it is often thought to imply the presence of a binary central star with a period of a few days to a few years. As one of the two stars expelled its outer layers, the other disrupted the outflow of material to form the bipolar shape. Examples * Homunculus Nebula around Eta Carinae * Hubble 5 * M2-9 – The M2-9, Wings of a Butterfly Nebula * OH231.8+4.2 – The Calabash Nebula or Rotten Egg Nebula * Mz3 (or Menzel 3) – The Mz 3, Ant Nebula * CRL 618 – The Westbrook Nebula * CRL 2688 – The Egg Nebula * HD 44179 – The Red Rectangle Nebula * MyCn18 – The Engraved Hourglass Nebula * – The Southern Crab Nebula * The Boomerang Nebula * NGC 2346 – Also known as the Butterfly Nebula * NGC 6302 – The Bug or Butterfly Nebula * KjPn 8 Nebula – The largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Nebulae
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionization, ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to planets. The term originates from the planet-like round shape of these nebulae observed by astronomers through early telescopes. The first usage may have occurred during the 1780s with the English astronomer William Herschel who described these nebulae as resembling planets; however, as early as January 1779, the French astronomer Antoine Darquier de Pellepoix described in his observations of the Ring Nebula, "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Though the modern interpretation is different, the old term is still used. All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
