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Tau Cassiopeiae
Tau Cassiopeiae (τ Cassiopeiae) is a solitary, orange hued star in the northern constellation of Cassiopeia. It is bright enough to be seen with the naked eye, having an apparent visual magnitude of +4.86. Based upon an annual parallax shift of 18.75 mas as seen from Earth, this system is located about 174 light years from the Sun. The spectrum of this star indicates it is an evolved, K-type giant star with a stellar classification of K1 IIIa. It is a suspected variable star of unknown type. Tau Cassiopeiae is 3.9 billion years old with about 1.44 times the mass of the Sun and 10 times the Sun's radius. It is radiating 40 times the Sun's luminosity from its expanded photosphere at an effective temperature of around 4,617 K. Naming In Chinese, (), meaning '' Flying Serpent'', refers to an asterism consisting of τ Cassiopeiae, α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, ε Cephei, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, AR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Cassiopeiae Diagram
Tau (uppercase Τ, lowercase τ, or \boldsymbol\tau; el, ταυ ) is the 19th letter of the Greek alphabet, representing the voiceless dental or alveolar plosive . In the system of Greek numerals, it has a value of 300. The name in English is pronounced or , but in Greek it is . This is because the pronunciation of the combination of Greek letters αυ can have the pronounciation of either , or , depending on what follows and if a diaeresis is present on the second vowel (see Greek orthography). Tau was derived from the Phoenician letter taw (𐤕). Letters that arose from tau include Roman T and Cyrillic Te (Т, т). The letter occupies the Unicode slots U+03C4 (lowercase) and U+03A4 (uppercase). In HTML, they can be produced with named entities (τ and Τ), decimal references (τ and Τ), or hexadecimal references (τ and Τ). Modern usage The lower-case letter τ is used as a symbol for: * Specific tax amoun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Of The Sun
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of the Sun. This equates to about two nonillion (short scale), two quintillion (long scale) kilograms or 2000 quettagrams: The solar mass is about times the mass of Earth (), or times the mass of Jupiter (). History of measurement The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance. The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of the Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of (9 arcseconds, compared to the present value of ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Cephei
Epsilon Cephei, Latinized from ε Cephei, is a star in the northern constellation of Cepheus. Based upon an annual parallax shift of 38.17 mas as seen from the Earth, it is located about 85 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 4.18. Properties Physical Characteristics This is a yellow-white hued, F-type star with a stellar classification of or F0 IV. Thus it may either be an F-type main sequence star showing an abundance excess of strontium, or it could be a more evolved subgiant star. It is a Delta Scuti variable star that cycles between magnitudes 4.15 and 4.21 every 59.388 minutes. The star displays an infrared excess, indicating the presence of a debris disk with a temperature of 65 K orbiting at a radius of 62 AU. This dust has a combined mass equal to 6.6% of the Earth's mass. Binary There is a faint companion star at an angular separation of along a position an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 206267
HD 206267A is a hierarchical triple star system in the northern circumpolar constellation of Cepheus. Two of the members form a spectroscopic binary that orbit each other with a period of 3.7 days, while a third member lies further away—it is unclear whether this third member is gravitationally bound to the pair. The system is emitting a stellar wind that reaches an exceptional velocity of 3,225 km/s, among the highest measured for stars of this type. This stellar system lies in the nebula IC 1396. All three components are massive stars, and the intense ultraviolet radiation they give off ionizes the gas of IC 1396, and causes compression denser globules of the nebula, leading to star formation. The stellar wind produced by the stars is strong enough to strip nearby stars of their protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protopl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi1 Cygni
Pi1 Cygni (π1 Cygni, abbreviated Pi1 Cyg, π1 Cyg) is a binary star in the northern constellation of Cygnus. It is visible to the naked eye, having a combined apparent visual magnitude of 4.66. The distance to this system can be roughly gauged by its annual parallax shift of 1.89 mas, which yields a separation of around 1,700 light years from the Sun, give or take a hundred light years. The two components are designated Pi1 Cygni A (officially named Azelfafage , the traditional name for the system) and B. Nomenclature ''π1 Cygni'' ( Latinised to ''Pi1 Cygni'') is the star's Bayer designation. The designations of the two components as ''Pi1 Cygni A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). It bore the traditional name ''Azelfafage'', derived from the Arabic ظلف الفرس ''Dhilf al-faras'' meaning "the horse track" or (pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi2 Cygni
Pi2 Cygni, Latinized from π2 Cygni, is a triple star system in the northern constellation of Cygnus. It is visible to the naked eye about 2.5° east-northeast of the open cluster M39, having an apparent visual magnitude of 4.24. Based upon an annual parallax shift of 2.95 mas, it is located at a distance of roughly 1,100 light years from the Sun. The inner pair of stars in this system form a single-lined spectroscopic binary with an orbital period of 72.0162 days and an eccentricity of 0.34. The primary, component A, is a B-type giant star with a stellar classification of B2.5 III. It is a Beta Cephei variable with an estimated 8.4 times the mass of the Sun and around 7.1 times the Sun's radius. The star is roughly 33 million years old and is spinning with a projected rotational velocity of 50 km/s. It is radiating 8,442 times the solar luminosity from its outer atmosphere at an effective temperature of around 20,815 K. The t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Lacertae
4 Lacertae is a single star in the northern constellation Lacerta, located about 1,900 light years away. This object visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.55. It is moving closer to the Earth with a heliocentric radial velocity of −26 km/s. This star is a suspected member of the Lac OB1 association. This is a supergiant star with a stellar classification of A0 Ib. The surface abundances show evidence of material that has been processed via the CNO cycle at the core. It has ten times the mass of the Sun and has expanded to about 59 times the Sun's radius. The star is around 25 million years old and is spinning with a projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ... of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Lacertae
Alpha Lacertae, Latinised from α Lacertae, is a single white-hued star in the constellation of Lacerta, located 103 light-years from the Sun. It is the brightest star in Lacerta with an apparent visual magnitude of 3.76. The star is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s. This is an ordinary A-type main-sequence star with a stellar classification of A1 V, which indicates it is generating energy through hydrogen fusion at its core. It is around 400 million years old with a relatively high rate of spin, showing a projected rotational velocity of 128 km/s. The star has 2.2 times the mass of the Sun and 2.1 times the Sun's radius. It is radiating 28 times the Sun's luminosity from its photosphere at an effective temperature of . Alpha Lacertae has a visual companion, CCDM J22313+5017B, of spectral type A and apparent visual magnitude 11.8, approximately 36 arcseconds away. The companion is optic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux. 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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flying Serpent (asterism)
Flying Serpent (''Tengshe'' 螣蛇) is an asterism (name for a group of stars) in the constellation "Encampment" (''Shixiu'' 室宿) in the Chinese constellation system. It is named after the mythological serpent, '' tengshe''. The ''Tengshe'' asterism was a group of "22 stars, occurring in the northern artof the "Encampment" () constellation, epresenting; or comprising the figure ofthe Heavenly Snake, chief of the water reptiles", according to the treatise on astronomy in the ''Book of Jin'' (''Jin Shu''). The Tengshe coincides with the lizard constellation Lacerta Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was defined in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" ..., and the northern parts of Lacerta occupy the center of Tengshe. References Chinese constellations {{China-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" (宿 ''xiù'') system also took shape around this period, by the time of King Wu Ding (1250–1192 BCE). Detailed records of astronomical observations began during the Warring States period (fourth century BCE) and flourished from the Han period onward. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate obser ... [...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, including 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 straightf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
