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LHA 120-N 55
LHA 120-N 55 is an emission nebula located within the Large Magellanic Cloud (LMC). It is a glowing clump of gas and dust that gets its light output from the hydrogen atoms shedding electrons within it. It was named in 1956, in a catalogue of H-alpha emission line objects in the LMC. Multiple dense molecular clumps have been detected, at least fifteen of which contain young stellar objects Young stellar object (YSO) denotes a star in its early stage of evolution. This class consists of two groups of objects: protostars and pre-main-sequence stars. Classification by spectral energy distribution A star forms by accumulation of mate .... References Emission nebulae Large Magellanic Cloud Dorado (constellation) {{nebula-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Large Telescope
The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, which are generally used separately but can be used together to achieve very high angular resolution. The four separate optical telescopes are known as ''Antu'', ''Kueyen'', ''Melipal'', and ''Yepun'', which are all words for astronomical objects in the Mapuche language. The telescopes form an array complemented by four movable Auxiliary Telescopes (ATs) of 1.8 m aperture. The VLT operates at visible light, visible and infrared wavelengths. Each individual telescope can detect objects roughly four billion times fainter than can be detected with the naked eye, and when all the telescopes are combined, the facility can achieve an angular resolution of about 0.002 arcsecond. In single telescope mode of operation angular resolution is ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Nebula
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. General information Usually, a young star will ionize part of the same cloud from which it was born, although only massive, hot stars can release sufficient energy to ionize a significant part of a cloud. In many emission nebulae, an entire cluster of young stars is contributing energy. Stars that are cooler than around 25,000K don't give off enough ultraviolet radiation with wavelengths shorter than 91.2nm (the wavelength needed in order to ionize Hydrogen atoms). This results in the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Magellanic Cloud
The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the Sagittarius Dwarf Spheroidal (16 kpc) and the possible dwarf irregular galaxy known as the Canis Major Overdensity. Based on the D25 isophote at the B-band (445 nm wavelength of light), the Large Magellanic Cloud is approximately across. It is roughly a hundredth as massive as the Milky WayMagellanic Cloud . ''''. 2009. Encyclopædia Britannica Online. 30 Aug. 2009. and is the fourth-largest g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H-alpha
H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha light is the brightest hydrogen line in the visible spectral range. It is important to astronomers as it is emitted by many emission nebulae and can be used to observe features in the Sun's atmosphere, including solar prominences and the chromosphere. Balmer series According to the Bohr model of the atom, electrons exist in quantized energy levels surrounding the atom's nucleus. These energy levels are described by the principal quantum number ''n'' = 1, 2, 3, ... . Electrons may only exist in these states, and may only transit between these states. The set of transitions from ''n'' ≥ 3 to ''n'' = 2 is called the Balmer series and its members are named sequentially by Greek letters: *''n'' = 3 to ''n'' = 2 is called Balmer-alpha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Line
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected ones of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets, which would otherwise be impossible. Types of line spectra Spectral lines are the result of interaction between a quantum system (usually atoms, but sometimes molecules or atomic nucleus, atomic nuclei) and a single photon. When a photon has about the right amount of photon energy, energy (which is connected to its frequency) to allow a change in the energy state of the system (in the case of an atom this is usually an electron changing Electron configuration, orbitals), the photon is absorbed. Then the energy will be spontaneously ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Young Stellar Objects
Young stellar object (YSO) denotes a star in its early stage of evolution. This class consists of two groups of objects: protostars and pre-main-sequence stars. Classification by spectral energy distribution A star forms by accumulation of material that falls in to a protostar from a circumstellar disk or envelope. Material in the disk is cooler than the surface of the protostar, so it radiates at longer wavelengths of light producing excess infrared emission. As material in the disk is depleted, the infrared excess decreases. Thus, YSOs are usually classified into evolutionary stages based on the slope of their spectral energy distribution in the mid-infrared, using a scheme introduced by Lada (1987). He proposed three classes (I, II and III), based on the values of intervals of spectral index \alpha \,: \alpha=\frac. Here \lambda \, is wavelength, and F_\lambda is Luminous flux, flux density. The \alpha \, is calculated in the wavelength interval of 2.2–20 m (near-infrared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Nebulae
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. General information Usually, a young star will ionize part of the same cloud from which it was born, although only massive, hot stars can release sufficient energy to ionize a significant part of a cloud. In many emission nebulae, an entire cluster of young stars is contributing energy. Stars that are cooler than around 25,000K don't give off enough ultraviolet radiation with wavelengths shorter than 91.2nm (the wavelength needed in order to ionize Hydrogen atoms). This results in the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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