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Theta Cancri
Theta Cancri, is a multiple star system in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinised from θ Cancri, and abbreviated Theta Cnc or θ Cnc. This star is visible to the naked eye as a dim point of light with an apparent visual magnitude of +5.32. The system is located at a distance of approximately from the Sun, based on parallax, and is drifting further away with a radial velocity of +44 km/s. Since it is near the ecliptic, it can be occulted by the Moon and, very rarely, by planets. The primary, designated component A, is K-type giant star with a stellar classification of K5 III, having exhausted the supply of hydrogen at its core, then cooled and expanded. At present it has 40 times the girth of the Sun. It is radiating 353 times the luminosity of the Sun at an effective temperature of . In Chinese astronomy, ''Ghost In folklore, a ghost is the soul or Spirit (supernatural entity), spirit of a dead Human, pe ... [...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] |
Giant Star
A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III. The terms ''giant'' and ''dwarf'' were coined for stars of quite different luminosity despite similar temperature or spectral type (namely K and M) by Ejnar Hertzsprung in 1905 or 1906. Giant stars have radii up to a few hundred times the Sun and luminosities over 10 times that of the Sun. Stars still more luminous than giants are referred to as supergiants and hypergiants. A hot, luminous main-sequence star may also be referred to as a giant, but any main-sequence star is properly called a dwarf, regardless of how large and luminous it is. Formation A star becomes a giant after all the hydrogen available for fusion at its core has been depleted and, as a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Stars
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a binary system of stars in mutual orbit, gravitationally bound to each other) or is an ''optical double'', a chance line-of-sight alignment of two stars at different distances from the observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. The only (possible) case of "binary star" whose two components are separately visible to the naked eye is the case of Mizar and Alcor (though actually a multiple-star system), but it is not known for certain whether Mizar and Alcor are gravitationally bound. Since the beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
K-type Giants
K-type may refer to: *AEC K-type The AEC K-type was a type of bus chassis built by Associated Equipment Company (AEC) from 1919 until 1926, mainly for use in London by the London General Omnibus Company (LGOC). Description The K-type was an important design that ended the ..., a bus chassis * K-type star, a stellar spectral classification * K-type filter, a type of electronic filter * K-type asteroid, an unusual kind of asteroid {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monthly Notices Of The Royal Astronomical Society
''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal in astronomy, astrophysics and related fields. It publishes original research in two formats: papers (of any length) and letters (limited to five pages). MNRAS publishes more articles per year than any other astronomy journal. The learned society journal has been in continuous existence since 1827 and became online only in 2020. It operates as a partnership between the Royal Astronomical Society (RAS), who select and peer-review the contents, and Oxford University Press (OUP), who publish and market the journal. Despite its name, MNRAS is no longer monthly, nor does it carry the notices of the RAS. In 2024 MNRAS became a purely gold open access journal. History The first issue of MNRAS was published on 9 February 1827 as ''Monthly Notices of the Astronomical Society of London'' and it has been in continuous publication ever since. It took its current name from the second vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Cancri
Delta Cancri is a star in the constellation of Cancer. It has the proper name Asellus Australis, Delta Cancri is its Bayer designation. This star is visible to the naked eye with an apparent visual magnitude of +3.94. Based on parallax measurements, it is located at a distance of from Earth. It is drifting further away with a line of sight velocity of 16 km/s. The star is 0.08 degree north of the ecliptic, so it can be occulted by the Moon and more rarely by planets; it is occulted (eclipsed) by the sun from about 31 July to 2 August. Thus the star can be viewed the whole night, crossing the sky at the start of February. Properties The spectrum of this star matches a spectral class of K0 III, with the luminosity class III indicating that it is a giant star that has exhausted the hydrogen at its core. With an estimated age of 2.45 billion years and 1.71 times the mass of the Sun, this star has expanded to 11.7 times the Sun's radius. It is radiating 60 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Cancri
Gamma Cancri is a star in the northern constellation of Cancer. Its name is a Bayer designation that is Latinized from γ Cancri, and abbreviated Gamma Cnc or γ Cnc. This star is formally named Asellus Borealis, pronouced , the traditional name of the system. Based on parallax measurements, it is located at a distance of approximately from the Sun. The star is drifting further away with a radial velocity of 29 km/s. In 1910 this star was reported to be a spectroscopic binary by O. J. Lee, but is now considered a single star. Since it is near the ecliptic, it can be occulted by the Moon. Nomenclature ''γ Cancri'' ( Latinised to ''Gamma Cancri'') is the star's Bayer designation. It bore the traditional name ''Asellus Borealis'' (Latin for "northern donkey"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Cancri
Eta Cancri is a single, orange-hued star in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinied from η Cancri, and abbreviated Eta Cnc or η Cnc. This is a faint star but visible to the naked eye with an apparent visual magnitude of 5.34. The annual parallax shift of as seen from Earth yields a distance estimate of from the Sun. It is moving further away with a radial velocity of +22 km/s. Due to its proximity to the ecliptic, it is subject to lunar occultations. A stellar classification of K3 III for Eta Cancri indicates that, at the estimated age of 3.9 billion years old, it has left the main sequence and become an evolved giant star. The spectrum shows unusually strong absorption lines of cyanogen. It has 1.5 times the mass of the Sun and has expanded to 17 times the Sun's radius. The star is radiating 87 times the Sun's luminosity from its photosphere at an effective temperature of around 4,415 K. In Chinese astrono ... [...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] |
Ghost (Chinese Constellation)
The Ghost mansion () is one of the Twenty-eight mansions of the Chinese constellations. It is one of the southern mansions of the Vermilion Bird The Vermilion Bird ( zh, c=朱雀, p=Zhūquè) is one of the Four Symbols of the Chinese constellations. According to Wuxing (Chinese philosophy), Wu Xing, the Taoism, Taoist five elemental system, it represents the Fire (Wu Xing), Fire element, .... Asterisms {{DEFAULTSORT:Ghost (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 China, 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). They flourished during the Han period (202 BCE – 220 CE) and subsequent dynasties with the publication of star catalogues. 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 framew ... [...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] |
