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Carbon Stars
A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes most of the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance. There are also some dwarf and supergiant carbon stars, with the more common giant stars sometimes being called classical carbon stars to distinguish them. In most stars (such as the Sun), the atmosphere is richer in oxygen than carbon. Ordinary stars not exhibiting the characteristics of carbon stars but cool enough to form carbon monoxide are therefore called oxygen-rich stars. Carbon stars have quite distinctive spectral characteristics, and they were first recognized by their spectra by Angelo Secchi in the 1860s, a pioneering time in astronomical spectroscopy. Spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y Canum Venaticorum RGB
Y, or y, is the twenty-fifth and penultimate letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. According to some authorities, it is the sixth (or seventh if including W) vowel letter of the English alphabet. Its name in English is ''wye'' (pronounced ), plural ''wyes''. In the English writing system, it mostly represents a vowel and seldom a consonant, and in other orthographies it may represent a vowel or a consonant. Name In Latin, Y was named ''I graeca'' ("Greek I"), since the classical Greek sound , similar to modern German ''ü'' or French ''u'', was not a native sound for Latin speakers, and the letter was initially only used to spell foreign words. This history has led to the standard modern names of the letter in Romance languages – ''i grego'' in Galician, ''i grega'' in Catalan, ''i grec'' in French and Romanian, and ''i greca'' in Italian – all meaning "Greek I". The n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triatomic Carbon
Tricarbon (systematically named 1λ2,3λ2-propadiene and ''catena''-tricarbon) is an inorganic compound with the chemical formula (also written (μ-C)Cor ). It is a colourless gas that only persists in dilution or solution as an adduct. It is one of the simplest unsaturated carbenes. Tricarbon can be found in interstellar space and can be produced in the laboratory by a process called laser ablation. Natural occurrence Tricarbon is a small carbon cluster first spectroscopically observed in the early 20th century in the tail of a comet by William Huggins and subsequently identified in stellar atmospheres. Small carbon clusters like tricarbon and dicarbon are regarded as soot precursors and are implicated in the formation of certain industrial diamonds and in the formation of fullerenes. C3 has also been identified as a transient species in various combustion reactions. Properties Chemical properties The chemical properties of C3 was investigated in the 1960s by Profes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philip Childs Keenan
Philip Childs Keenan (March 31, 1908 – April 20, 2000) was an American astronomer. Keenan was an American spectroscopist who collaborated with William Wilson Morgan and Edith Kellman (1911–2007) to develop the MKK stellar spectral classification system between 1939 and 1943. This two-dimensional classification system (temperature & luminosity) was further revised by Morgan and Keenan in 1973. The MK system remains the standard stellar spectral classification system used by astronomers today. During their long collaboration, Keenan tended to focus his research on stars cooler than the Sun, while Morgan emphasized the hotter stars. Keenan had a long and productive career, publishing his final scientific paper in 1999, seventy years after his first. Honors Named after him *Asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar Sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Astrophysical Journal
''The Astrophysical Journal'' (''ApJ'') is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and became an electronic-only journal in 2015. Since 1953, ''The Astrophysical Journal Supplement Series'' (''ApJS'') has been published in conjunction with ''The Astrophysical Journal'', with generally longer articles to supplement the material in the journal. It publishes six volumes per year, with two 280-page issues per volume. ''The Astrophysical Journal Letters'' (''ApJL''), established in 1967 by Subrahmanyan Chandrasekhar as Part 2 of ''The Astrophysical Journal'', is now a separate journal focusing on the rapid publication of high-impact astronomical research. The three journals were published by the University of Chicago Press for the American Astronomical Society until, in January 2009, publication was transferred to IOP Publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Superba
La Superba (Y CVn, Y Canum Venaticorum) is a strikingly red giant star in the constellation Canes Venatici. It is faintly visible to the naked eye, and the red colour is very obvious in binoculars. It is a carbon star and semiregular variable. Visibility La Superba is a semiregular variable star, varying by about a apparent magnitude, magnitude over a roughly 160-day cycle, but with slower variation over a larger range. Periods of 194 and 186 days have been suggested, with a resonance between the periods. Y CVn is one of the reddest stars known, and it is among the brightest of the giant red carbon stars. It is the brightest of known Carbon star#The Revised Morgan–Keenan system, J-stars, which are a very rare category of carbon stars that contain large amounts of carbon-13 (carbon atoms with 7 neutrons instead of the usual 6). The 19th century astronomer Angelo Secchi, impressed with its beauty, gave the star its common name, which is now accepted by the Internatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grating into a spectrum exhibiting the Continuum (spectrum), rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the cool ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Interstellar And Circumstellar Molecules
This is a list of molecules that have been detected in the interstellar medium and circumstellar envelopes, grouped by the number of component atoms. The chemical formula is listed for each detected compound, along with any ionized form that has also been observed. Background The molecules listed below were detected through astronomical spectroscopy. Their spectral features arise because molecules either absorb or emit a photon of light when they transition between two molecular energy levels. The energy (and thus the wavelength) of the photon matches the energy difference between the levels involved. Molecular electronic transitions occur when one of the molecule's electrons moves between molecular orbitals, producing a spectral line in the ultraviolet, visible light, optical or near-infrared parts of the electromagnetic spectrum. Alternatively, a vibrational transition transfers Quantum, quanta of energy to (or from) vibrations of molecular bonds, producing signatures in the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CW Leonis
CW Leonis or IRC +10216 is a variable carbon star that is embedded in a thick dust envelope. It was first discovered in 1969 by a group of astronomers led by Eric Becklin, based upon infrared observations made with the 62-inch Caltech Infrared Telescope at Mount Wilson Observatory. Its energy is emitted mostly at infrared wavelengths. At a wavelength of 5 μm, it was found to have the highest flux of any object outside the Solar System. Properties CW Leonis is believed to be in a late stage of its life, blowing off its own sooty atmosphere to form a white dwarf. Based upon isotope ratios of magnesium, the initial mass of this star has been constrained to lie between 3–5 solar masses. The mass of the star's core, and the final mass of the star once it becomes a white dwarf, is about 0.7–0.9 solar masses. Its bolometric luminosity varies over the course of a 649-day pulsation cycle, ranging from a minimum of about 6,250 times the Sun's luminosity up to a peak o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submillimetre Astronomy
Submillimetre astronomy or submillimeter astronomy (see spelling differences) is the branch of observational astronomy that is conducted at submillimetre wavelengths (i.e., terahertz radiation) of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre. It is still common in submillimetre astronomy to quote wavelengths in 'microns', the old name for micrometre. Submillimetre observations can be used to trace emission from gas and dust, including the CI, CO, and CII lines. Sources behind this emission include molecular clouds and dark cloud cores, which can be used to clarify the process of star formation from earliest collapse to stellar birth, by determining chemical abundances in dark clouds and the cooling mechanisms for the molecules which comprise them. Other sources include protoplanetary discs, dusty starburst galaxies in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivided u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium Flash
A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low-mass stars (between 0.5-0.44 solar masses () and 2.0 ) during their red giant phase. The Sun is predicted to experience a flash 1.2 billion years after it leaves the main sequence. A much rarer runaway helium fusion process can also occur on the surface of Accretion (astrophysics), accreting white dwarf stars. Low-mass stars do not produce enough gravity, gravitational pressure to initiate normal helium fusion. As the hydrogen in the core is exhausted, some of the helium left behind is instead compacted into degenerate matter, supported against gravitational collapse by quantum mechanics, quantum mechanical pressure rather than ideal gas law, thermal pressure. Subsequent hydrogen shell fusion further increases the mass of the core until it reaches temperature of approximately 100 million kelvin, which is hot enough to initiate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium
Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyish-white color that closely resembles hafnium and, to a lesser extent, titanium. It is solid at room temperature, Ductility, ductile, malleable and corrosion-resistant. The name ''zirconium'' is derived from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian Language, Persian ''Jargoon, zargun'' (zircon; ''zar-gun'', "gold-like" or "as gold"). Besides zircon, zirconium occurs in over 140 other minerals, including baddeleyite and eudialyte; most zirconium is produced as a byproduct of minerals mined for titanium and tin. Zirconium forms a variety of inorganic chemistry, inorganic compounds, such as zirconium dioxide, and organometallic compounds, such as zirconocene dichloride. Five isotope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
