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Zone Of Avoidance
The Zone of Avoidance (ZOA, ZoA), or Zone of Galactic Obscuration (ZGO), is the area of the sky that is obscured by the Milky Way. The Zone of Avoidance was originally called the Zone of Few Nebulae in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in John Herschel's '' General Catalogue of Nebulae''.Kraan-Korteweg & Lahav 2000, p. 2 Background When viewing space from Earth, the attenuation, interstellar dust and stars in the plane of the Milky Way (the galactic plane) obstruct the view of around 20% of the extragalactic sky at visible wavelengths. As a result, optical galaxy catalogues are usually incomplete close to the galactic plane. Modern developments Many projects have attempted to bridge the gap in knowledge caused by the Zone of Avoidance. The dust and gas in the Milky Way cause extinction at optical wavelengths, and foreground stars can be confused with background galaxies. However, the effect of extinction drops at lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way Infrared
Milky is an Italian dance music production group consisting of producers Giordano Trivellato and Giuliano Sacchetto, with Italian singer Giuditta serving as their lead singer on their album ''Star''. Although Giuditta Gazza was the singer on the recordings, a model, the Egyptian-born and German-raised Sabrina Elahl, was used for the music video for the "Just the Way You Are (Milky song), Just the Way You Are" single. The same model was used for the gramophone record, vinyl cover. Elahl's voice did not appear on any of Milky's recordings, where all songs were sung by Giuditta. Giuditta can be seen on the "Be My World" twelve-inch single, 12" cover as well as in the video for "In My Mind". Two of the tracks from ''Star'' eventually became hits in the United States; "Just the Way You Are" reached the chart-topper, num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2MASS
The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and at the Cerro Tololo Inter-American Observatory in Chile, each using a 1.3-meter telescope for the Northern and Southern Hemisphere, respectively. It was conducted in the short-wavelength infrared at three distinct frequency bands ( J, H, and K) near 2 micrometres, from which the photometric survey with its HgCdTe detectors derives its name. 2MASS produced an astronomical catalog with over 300 million observed objects, including minor planets of the Solar System, brown dwarfs, low-mass stars, nebulae, star clusters and galaxies. In addition, 1 million objects were cataloged in the ''2MASS Extended Source Catalog'' (''2MASX''). The cataloged objects are designated with a "2MASS" and "2MASX"-prefix respectively. Catalog The final d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Attractor
The Great Attractor is a gravitational anomaly in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster. The observed anomalies suggest a localized concentration of mass millions of times more massive than the Milky Way. However, it is inconveniently obscured by our own Milky Way's galactic plane, lying behind the Zone of Avoidance (ZOA), so that in visible light wavelengths, the Great Attractor is difficult to observe directly. In fact, it will not be for another hundred million years that Earth will be on the other side of the Milky Way galaxy, allowing us to see past the galactic plane. The anomaly is observable by its effect on the motion of galaxies and their associated clusters over a region of hundreds of millions of light-years across the universe. These galaxies are observable above and below the ZOA; all are redshifted in accordance with the Hubble flow, indicating that they are receding relative to us and to each other, but the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactic Plane
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galactic poles'' usually refer specifically to the plane and poles of the Milky Way, in which Planet Earth is located. Some galaxies are irregular and do not have any well-defined disk. Even in the case of a barred spiral galaxy like the Milky Way, defining the galactic plane is slightly imprecise and arbitrary since the stars are not perfectly coplanar. In 1959, the IAU defined the position of the Milky Way's north galactic pole as exactly RA = , Dec = in the then-used B1950 epoch; in the currently-used J2000 epoch, after precession is taken into account, its position is RA , Dec . This position is in Coma Berenices, near the bright star Arcturus; likewise, the south galactic pole lies in the constellation Sculptor. The "zero of longitude" of galactic coor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extragalactic Background Light
The diffuse extragalactic background light (EBL) is all the accumulated radiation in the universe due to star formation processes, plus a contribution from active galactic nuclei (AGNs). This radiation covers almost all wavelengths of the electromagnetic spectrum, except the microwave, which is dominated by the primordial cosmic microwave background. The EBL is part of the diffuse extragalactic background radiation (DEBRA), which by definition covers the entire electromagnetic spectrum. After the cosmic microwave background, the EBL produces the second-most energetic diffuse background, thus being essential for understanding the full energy balance of the universe. The understanding of the EBL is also fundamental for extragalactic very-high-energy (VHE, 30 GeV-30 TeV) astronomy. VHE photons coming from cosmological distances are attenuated by pair production with EBL photons. This interaction is dependent on the spectral energy distribution (SED) of the EBL. Therefore, it is necessa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwingeloo 2
Dwingeloo 2 is a small irregular galaxy discovered in 1996 and located about 10 million light-years away from the Earth. Its discovery was a result of the Dwingeloo Obscured Galaxy Survey (DOGS) of the Zone of Avoidance using the Dwingeloo Radio Observatory. Dwingeloo 2 is a companion galaxy of Dwingeloo 1. Dwingeloo 2 was first detected at radio wavelengths from the 21 cm emission line of neutral atomic hydrogen (known to astronomers as HI) in the course of follow-up observations after the discovery of Dwingeloo 1. Dwingeloo 2 is thought to be a member of the IC 342/Maffei Group, a galaxy group adjacent to the Local Group The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form .... The galaxy recedes from the Milky Way at the speed of about 241 km/s. The visible radius of Dwi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwingeloo 1
Dwingeloo 1 is a barred spiral galaxy about 10 million light-years away from the Earth, in the constellation Cassiopeia. It lies in the Zone of Avoidance and is heavily obscured by the Milky Way. The size and mass of Dwingeloo 1 are comparable to those of Triangulum Galaxy. Dwingeloo 1 has two smaller satellite galaxies — Dwingeloo 2 and MB 3 — and is a member of the IC 342/Maffei Group of galaxies. Discovery The Dwingeloo 1 galaxy was discovered in 1994 by the Dwingeloo Obscured Galaxy Survey (DOGS) using the Dwingeloo Radio Observatory, which searched for neutral hydrogen (HI) radio emissions at the wavelength of 21 cm from objects in the Zone of Avoidance. In this zone gas and dust in the disk of the Milky Way galaxy block the light from the galaxies lying behind it. The galaxy was, however, first noted as an unremarkable feature on Palomar Sky Survey plates earlier in the same year, but was not recognized as such. It was also independently discovered a few ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Line
The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , which is equivalent to the vacuum wavelength of in free space. This frequency falls below the microwave region of the electromagnetic spectrum, which begins at 3.0 GHz (10 cm wavelength), and it is observed frequently in radio astronomy because those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light. This line is also the theoretical basis of the hydrogen maser. The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen 1 s ground state that have an energy difference of []. It is called the ''spin-flip transition''. The frequency, , of the quantum, quanta that are emitted by this transition between tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21 Cm Line
The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , which is equivalent to the wavelength#General media, vacuum wavelength of in free space. This frequency falls below the microwave region of the electromagnetic spectrum, which begins at 3.0 GHz (10 cm wavelength), and it is observed frequently in radio astronomy because those radio waves can penetrate the large clouds of interstellar cosmic dust that are opacity (optics), opaque to visible light. This line is also the theoretical basis of the hydrogen maser. The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen principle quantum number, 1 azimuthal quantum number, s ground state that have an energy difference of []. It is called the ''spin-flip transit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paolo Maffei
Paolo Maffei (2 January 1926 – 1 March 2009) was an Italian astrophysicist and science writer. He was born in Arezzo and was director of the Catania Observatory and an astronomer at Arcetri, Bologna, Asiago and Hamburg. He studied comets, variable stars, galaxies and the evolution of the universe. An internationally renowned astronomer, he was one of the pioneers of infrared astronomy research. In 1968 he discovered through infrared analysis two galaxies, otherwise unobservable because their light emission in the visible frequencies is absorbed by the dust that fills the plane of the Milky Way. The two galaxies were named after him: Maffei-1 (a galaxy that, if directly observable, would become one of the most visible objects in the sky) and Maffei-2. The two galaxies are the main constituents of the group known as "Maffei's Group of galaxies 1". Maffei also a historian of astronomy and popularizer of astronomy through a series of books, including ''Al di là della ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maffei 2
Maffei 2 is an intermediate spiral galaxy about 10 million light-years away in the constellation Cassiopeia. Maffei 2 and Maffei 1 were both discovered by Paolo Maffei in 1968 from their infrared emission. Maffei 2 lies in the Zone of Avoidance and is about 99.5% obscured by the Milky Way's foreground dust clouds, and as a result is barely detectable at optical wavelengths. It had been suggested soon after its discovery that Maffei 2 may be a member of the Local Group, but it is now thought to be a member of another nearby group, the IC 342/Maffei Group, the galaxy group that is the closest to the Local Group. Gallery Heart and Soul nebulae.jpg, Near the bottom middle of this image, Maffei 2 is nearly obscured by the gas and dust in our own Galaxy See also * Dwingeloo 1 * NGC 1300 NGC 1300 is a barred spiral galaxy located about 61 million light-years away in the constellation Eridanus. The galaxy is about 110,000 light-years across. It is a member of the Eridanu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
