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A pinwheel nebula is a nebulous region in the shape of a pinwheel.
A pinwheel is a simple child's toy made of a wheel of paper or plastic curls attached at its axle to a stick by a pin. It is designed to spin when blown upon by a person or by the wind. It is a predecessor to more complex whirligigs.
The term 'Pinwheel nebula' is an antiquated misnomer used by observers before Edwin Hubble realized that many of these spiral shaped nebulae were actually 'island universes' or what we now call galaxies.[ citation needed ]
A misnomer is a name that is incorrectly applied to a thing. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by something to which the name no longer applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean "misunderstanding" or "popular misconception", and a number of misnomers remain in common usage — which is to say, the fact of a word being a misnomer does not necessarily make usage of the word incorrect.
Edwin Powell Hubble was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time.
Some Wolf–Rayet stars are surrounded by pinwheel nebulae. These nebulae are formed from the dust that is spewed out of a binary star system. The stellar winds of the two stars collide and form two dust lanes that spiral outward with the rotation of the system. An example of this is WR 104.
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. Their surface temperatures range from 30,000 K to around 200,000 K, hotter than almost all other stars. They were previously called W-type stars referring to their spectral classification.
A binary star is a star system consisting of two stars orbiting around their common barycenter. Systems of two or more stars are called multiple star systems. These systems, especially when more distant, often appear to the unaided eye as a single point of light, and are then revealed as multiple by other means. Research over the last two centuries suggests that half or more of visible stars are part of multiple star systems.
WR 104 is a triple star system located about 7,500 light-years (2,300 pc) from Earth. The primary star is a Wolf-Rayet star, abbreviated as WR, with a B0.5 main sequence star in close orbit and another more distant fainter companion.
Aperture masking interferometry is a form of speckle interferometry, that allows diffraction limited imaging from ground-based telescopes, and is a planned high contrast imaging mode on the James Webb Space Telescope. This technique allows ground-based telescopes to reach the maximum possible resolution, allowing ground-based telescopes with large diameters to produce far greater resolution than does the Hubble Space Telescope. The principal limitation of the technique is that it is applicable only to relatively bright astronomical objects. A mask is placed over the telescope which only allows light through a small number of holes. This array of holes acts as a miniature astronomical interferometer. The method was developed by John E. Baldwin and collaborators in the Cavendish Astrophysics Group.
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A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million stars to giants with one hundred trillion stars, each orbiting its galaxy's center of mass.
A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, the term was used to describe any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was once referred to as the Andromeda Nebula before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others.
In astronomy, reflection nebulae are clouds of interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible. Thus, the frequency spectrum shown by reflection nebulae is similar to that of the illuminating stars. Among the microscopic particles responsible for the scattering are carbon compounds and compounds of other elements such as iron and nickel. The latter two are often aligned with the galactic magnetic field and cause the scattered light to be slightly polarized.
An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic cm. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered.
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are often surrounded by a much fainter halo of stars, many of which reside in globular clusters.
NGC 5189 is a planetary nebula in the constellation Musca. It was discovered by James Dunlop on 1 July 1826, who catalogued it as Δ252. For many years, well into the 1960s, it was thought to be a bright emission nebula. It was Karl Gordon Henize in 1967 who first described NGC 5189 as quasi-planetary based on its spectral emissions.
NGC 3603 is a nebula situated in the Carina spiral arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive HII region containing a very compact open cluster HD 97950.
The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe; Shapley believed that distant nebulae were relatively small and lay within the outskirts of Earth's home galaxy, while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant.
A Wolf–Rayet nebula is a nebula which surrounds a Wolf–Rayet star.
WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as a supernova.
WR 102ka, also known as the Peony star, is a Wolf–Rayet star that is one of several candidates for the most luminous-known star in the Milky Way.
LL Pegasi is a Mira variable star surrounded by a pinwheel-shaped nebula, IRAS 23166+1655, thought to be a preplanetary nebula. It is a binary system that includes an extreme carbon star. The pair is hidden by the dust cloud ejected from the carbon star and is only visible in infrared light.
AB7, also known as SMC WR7, is a binary star in the Small Magellanic Cloud. A Wolf–Rayet star and a supergiant companion of spectral type O orbit in a period of 19.56 days. The system is surrounded by a ring-shaped nebula known as a bubble nebula.
A colliding-wind binary is a binary star system in which the two members are massive stars that emit powerful, radiatively-driven stellar winds. The location where these two winds collide produces a strong shock front that can cause radio, X-ray and possibly synchrotron radiation emission. Wind compression in the bow shock region between the two stellar winds allows dust formation. When this dust streams away from the orbiting pair, it can form a pinwheel nebula of spiraling dust. Such pinwheels have been observed in the Quintuplet Cluster
WR 25 is a binary star system in the turbulent star forming region Carina Nebula, about 6,800 light-years from Earth. It contains a Wolf-Rayet star and a hot luminous companion, and is a member of the Trumpler 16 cluster.
WR 147 is a star system in the constellation of Cygnus. Its distance has been calculated to be around 2,100 ± 200 light years away from the Earth. This puts the star in front of the OB association known as Cygnus OB2. The system is extremely reddened by interstellar extinction - that is, dust in front of the star scatters much of the blue light coming from WR 147, leaving the star appearing reddish.
Theta Muscae is a multiple star system in the southern constellation Musca with an apparent magnitude of 5.5. It is the second-brightest Wolf–Rayet star in the sky, although much of the visual brightness comes from the massive companions and it is not one of the closest of its type.
Apep is a triple star system containing a Wolf–Rayet binary and a hot supergiant, located in the constellation of Norma. Named after the serpent deity from Egyptian mythology, the star system is surrounded by a vast complex of stellar wind and cosmic dust thrown into space by the high rotation speed of the binary's primary star and formed into a "pinwheel" shape by the secondary star's influence. Ground-based studies of the system in the 2010s concluded that the system was the best known gamma-ray burst progenitor candidate in the Milky Way galaxy.
