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Upsilon Ceti
Upsilon Ceti, Latinized from υ Ceti, is a solitary star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.95. Based upon an annual parallax shift of 11.14 mas, it is located about 293 light years from the Sun. This star was designated Upsilon Ceti by Bayer and 59 Ceti by Flamsteed. Flamsteed also gave it the designation Upsilon2 Ceti to distinguish it from 56 Ceti, which he called Upsilon1. Flamsteed's superscripted designations, however, are not in general use today. For ancient Arabic astronomers, this star with η Cet (Deneb Algenubi), θ Cet (Thanih al Naamat), τ Cet (Durre Menthor) and ζ Cet (Baten Kaitos), formed Al Naʽāmāt (النعامات), the Hen Ostriches In Chinese, (), meaning ''Sickle'', refers to an asterism consisting of υ Ceti, 48 Ceti and 56 Ceti. Consequently, the Chinese name for υ Ceti itself is (, en, the Fourth Star of Sickle.) Upsilon Ceti is an evolved ... [...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] |
Milliarcsecond
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in astro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Star Names
Chinese star names (Chinese: , ''xīng míng'') are named according to ancient Chinese astronomy and astrology. The sky is divided into star mansions (, ''xīng xiù'', also translated as "lodges") and asterisms (, ''xīng guān''). The system of 283 asterisms under Three Enclosures and Twenty-eight Mansions was established by Chen Zhuo of the Three Kingdoms period, who synthesized ancient constellations and the asterisms created by early astronomers Shi Shen, Gan De and Wuxian. Since the Han and Jin Dynasties, stars have been given reference numbers within their asterisms in a system similar to the Bayer or Flamsteed designations, so that individual stars can be identified. For example, Deneb (α Cyg) is referred to as (''Tiān Jīn Sì'', the Fourth Star of Celestial Ford). In the Qing Dynasty, Chinese knowledge of the sky was improved by the arrival of European star charts. ''Yixiang Kaocheng'', compiled in mid-18th century by then deputy Minister of Rites Ignaz Kögler, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
48 Ceti
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48 may refer to: * 48 (number) * one of the years 48 BC, AD 48, 1948, 2048 * ''48'' (novel) * 48'' (magazine) * "48", a song by Tyler, the Creator from the album ''Wolf'' * 48, a phone network brand of Three Ireland * "Forty Eight", a song by Karma to Burn from the album '' V'', 2011 See also * A48 (other) A48 may refer to : * A48 motorway (France), a road connecting the A43 and Grenoble * A48 road (Great Britain), a road connecting Gloucester, England and Carmarthen, Wales * Autovía A-48, a motorway under construction connecting Cadiz and Algeciras, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wall (Chinese Constellation)
The Wall mansion () is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise The Black Tortoise () is one of the Four Symbols of the Chinese constellations. Despite its English name, it is usually depicted as a tortoise entwined together with a snake. The name used in East Asian languages does not mention either anima .... Asterisms {{Chinese constellation Chinese constellations ... [...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] |
Zeta Ceti
Zeta Ceti (ζ Ceti, abbreviated Zeta Cet, ζ Cet) is a binary star in the equatorial constellation of Cetus. It has a combined apparent visual magnitude of 3.74, which is bright enough to be seen with the naked eye. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 235 light-years from the Sun. Zeta Ceti is the primary or 'A' component of a double star system designated WDS J01515-1020 (the secondary or 'B' component is HD 11366). Zeta Ceti's two components are therefore designated WDS J01515-1020 Aa and Ab. Aa is officially named Baten Kaitos , the traditional name of the entire system. Nomenclature ''ζ Ceti'' ( Latinised to ''Zeta Ceti'') is the binary pair's Bayer designation. WDS J01515-1020 A is its designation in the Washington Double Star Catalog. The designations of the two components as WDS J01515-1020 Aa and Ab derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Ceti
Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient relative to the Sun. It can be seen with the unaided eye with an apparent magnitude of 3.5. As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = , Dec = , which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of , the Sun would have an apparent magnitude m = M_v + 5 \cdot (\log_ 3.64 - 1) = 2.6. Observations have detected more than ten times as much dust surrounding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ceti
Theta Ceti, Latinized from θ Ceti, is a solitary, orange-hued star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.60. Based upon an annual parallax shift of 28.66 mas as seen from Earth, it is located about 114 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.10 due to interstellar dust. With an age of about 2.2 billion years, this is an evolved, K-type giant star with a stellar classification of K0 III. It is a red clump star on the horizontal branch, which means it is generating energy through helium fusion at its core. The star has an estimated 1.8 times the mass of the Sun and has expanded to 10 times the Sun's radius. It is radiating 53 times the solar luminosity from its photosphere at an effective temperature of 4,660 K. Name In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Ceti
Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of . This is a giant star that has been chosen a standard for the stellar classification of K2−IIIb. It has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a strong CN star with higher than normal abundance of cyanogen and iron relative to other stars of its class.) It is a red clump star that is generating energy through the nuclear fusion of helium at its core. Eta Ceti may have slightly more mass than the Sun and its outer envelope has expanded to 15 times the Sun's radiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
56 Ceti
56 Ceti is a single star located in the equatorial constellation of Cetus. Not found in the original Bayer catalogue, it was given the Bayer-like designation Upsilon1 Ceti by Flamsteed to distinguish it from Bayer's Upsilon Ceti, which Flamsteed designated Upsilon2 or 59 Ceti. In 1801, J. E. Bode included this designation in his ''Uranographia'', but the superscripted designations Upsilon1 and Upsilon2 are not in general use today. ''56 Ceti'' is the Flamsteed designation for this star. This star is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.85. It is located about 440 light years from the Sun, based on parallax, and is drifting further away with a radial velocity of +27 km/s. 56 Ceti is an aging giant star with a stellar classification of K3III, having exhausted the supply of hydrogen at its core and expanded to 39 times the Sun's radius. It is radiating 391 times the luminosity of the Sun from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
