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Θ Carinae
θ Carinae, Latinized as Theta Carinae, is a spectroscopic binary star in the southern constellation of Carina. With an apparent visual magnitude of 2.76, it is the brightest star in the open star cluster IC 2602. It marks the northeastern end of the Diamond Cross asterism. Parallax measurements from the Hipparcos mission place this star at a distance of about from Earth. Properties The MKK stellar classification of this star is B0.5 Vp, which indicates this B-type main sequence star generates energy through the nuclear fusion of hydrogen in its core. The 'p' suffix designates peculiar spectral features, which have been observed in both optical and ultraviolet wavelengths. Theta Carinae is a single-lined spectroscopic binary with a 2.2 day period; the shortest known orbital period among massive stars, suggesting earlier mass transfer between the two components, possibly explaining the spectral peculiarities. In this spectroscopic system, the primary star is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a 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 celestial body, as they are subject to 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 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 bodies) can be used to generate an ephemeris, a table of values giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observational astronomy, observed pattern or group of stars in the sky. Asterisms can be any identified star pattern, and therefore are a more general concept than the IAU designated constellations, 88 formally defined constellations. Constellations are based upon asterisms, but unlike asterisms, constellations are defined regions with official boundaries which together encompass the entire sky. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PP Carinae
p Carinae is a star in the southern constellation of Carina (constellation), Carina. It has the variable star designation PP Carinae and, at an apparent visual magnitude of +3.3, is readily visible to the naked eye from the southern hemisphere. From the observed parallax shift of this star as the Earth orbits the Sun, its distance can be estimated as roughly with a 6% margin of error. It is considered to be a member of the open cluster IC 2602 although it lies well outside the core visible group of stars. The star is a B-type main sequence star with a stellar classification of B4 Vne. The 'ne' suffix indicates it is a rapidly rotating Be star that is surrounded by hot circumstellar gas. This material adds emission lines to the stellar spectrum, spectrum of the star. It has a projected rotational velocity of , with about 7.6 times the mass and eight times the radius of the Sun. Alan William James Cousins announced the discovery that this star is a variable star, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V337 Carinae
V337 Carinae (V337 Car, q Carinae) is a K-type bright giant star in the constellation of Carina. It is an irregular variable and has an apparent visual magnitude which varies between 3.36 and 3.44. It is easily visible to the naked eye, except in brightly-lit urban areas. Benjamin Apthorp Gould listed the star as possibly variable in his 1879 publication ''Uranometria Argentina'', when it was known as q Carinae. It was given its variable star designation, V337 Carinae, nearly 100 years later, in 1973. V337 Carinae has a spectral class of K2.5II, indicating a bright giant. It is considered likely to be on the red giant branch of stars fusing hydrogen around an inert helium core. However, with a mass nine times that of the Sun, it is also an accepted supernova candidate. Its limb-darkened angular diameter has been measured using interferometry Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superpositio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Constellations
Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenistic tradition. The Song dynasty (13th-century) Suzhou planisphere shows a total of 283 asterisms, comprising a total of 1,565 individual stars. The asterisms are divided into four groups, the Twenty-Eight Mansions (, ''Èrshíbā Xiù'') along the ecliptic, and the Three Enclosures of the northern sky. The southern sky was added as a fifth group in the late Ming dynasty based on European star charts, comprising an additional 23 asterisms. The Three Enclosures (, ''Sān Yuán'') include the Purple Forbidden Enclosure, which is centered on the north celestial pole and includes those stars which could be seen year-round,Needham, J.Astronomy in Ancient and Medieval China. ''Philosophical Transactions of the Royal Society of London''. Ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Language
Chinese ( or ) is a group of languages spoken natively by the ethnic Han Chinese majority and List of ethnic groups in China, many minority ethnic groups in China, as well as by various communities of the Chinese diaspora. Approximately 1.39 billion people, or 17% of the global population, speak a variety of Chinese as their first language. Chinese languages form the Sinitic languages, Sinitic branch of the Sino-Tibetan language family. The spoken varieties of Chinese are usually considered by native speakers to be dialects of a single language. However, their lack of mutual intelligibility means they are sometimes considered to be separate languages in a Language family, family. Investigation of the historical relationships among the varieties of Chinese is ongoing. Currently, most classifications posit 7 to 13 main regional groups based on phonetic developments from Middle Chinese, of which the most spoken by far is Mandarin Chinese, Mandarin with 66%, or around 800&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-type Star
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature when the body's emissivity curve (as a function of wavelength) is not known. When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a black body), the actual temperature of the body will be higher than the effective temperature. The net emissivity may be low due to surface or atmospheric properties, such as the greenhouse effect. Star The effective temperature of a star is the temperature of a black body with the same luminosity per ''surface area'' () as the star and is defined according to the Stefan–Boltzmann law . Notice that the total ( bolometric) luminosity of a star is then , where is the stellar radius. The definition of the stellar radius is obviously not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Straggler
A blue straggler is a type of star that is more luminous and bluer than expected. Typically identified in a stellar cluster, they have a higher effective temperature than the main sequence turnoff point for the cluster, where ordinary stars begin to evolve towards the red giant branch. Blue stragglers were first discovered by Allan Sandage in 1953 while performing photometry of the stars in the globular cluster M3. Description Standard theories of stellar evolution hold that the position of a star on the Hertzsprung–Russell diagram should be determined almost entirely by the initial mass of the star and its age. In a cluster, stars all formed at approximately the same time, and thus in an H–R diagram for a cluster, all stars should lie along a clearly defined curve set by the age of the cluster, with the positions of individual stars on that curve determined solely by their initial mass. With masses two to three times that of the rest of the main-sequence cluster stars, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fusion
Nuclear fusion is a nuclear reaction, reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutrons, neutron by-products. The difference in mass between the reactants and products is manifested as either the release or absorption (electromagnetic radiation), absorption of energy. This difference in mass arises as a result of the difference in nuclear binding energy between the atomic nuclei before and after the fusion reaction. Nuclear fusion is the process that powers all active stars, via many Stellar nucleosynthesis, reaction pathways. Fusion processes require an extremely large Lawson criterion, triple product of temperature, density, and confinement time. These conditions occur only in Stellar core, stellar cores, advanced Nuclear weapon design, nuclear weapons, and are approached in List of fusion experiments, fusion power experiments. A nuclear fusion process that produces atomic nuclei lighter than nickel-62 is generally exothermic, due t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-type Main Sequence Star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have strong neutral helium absorption lines, which are most prominent at the B2 subclass, and moderately strong hydrogen lines. Examples include Regulus, Algol A and Acrux. History This class of stars was introduced with the Harvard sequence of stellar spectra and published in the ''Revised Harvard photometry'' catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is 1/5 of the way from type B (or ... [...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] |
