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Eta Boötis
Eta Boötis is a candidate binary star system in the constellation of Boötes. Its name is a Bayer designation that is Latinized from η Boötis, and abbreviated Eta Boo or η Boo. This system is visible to the naked eye as a point of light with an apparent visual magnitude of 2.68. Based on parallax measurements obtained during the Hipparcos mission, it is approximately distant from the Sun. It is drifting closer with a radial velocity of −5.3 km/s. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It forms a double star with the star BD+19 2726. As a constituent of a double pair, Eta Boötis is also designated WDS J13547+1824A, with its two components being designated Aa (formally named Muphrid , the traditional name for the entire system) and Ab. (As part of a binary pair, they are also designated Eta Boötis A and B, respectively.) is also designated WDS J13547+1824B. Nomenclature ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boötes
Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'ox-driver'; from ''boûs'' 'cow'). One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Boötes is now one of the 88 modern constellations. It contains the List of brightest stars, fourth-brightest star in the night sky, the orange giant Arcturus. Epsilon Boötis, or Izar, is a colourful multiple star popular with amateur astronomers. Boötes is home to many other bright stars, including eight above the fourth magnitude and an additional 21 above the fifth magnitude, making a total of 29 stars easily visible to the naked eye. History and mythology In ancient Babylon, the stars of Boötes were known as SHU.PA. They were apparently depicted as the god Enlil, who was the leader of the Babylonian religion, Babyloni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IAU Working Group On Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage. The IAU states that it is keen to make a distinction between the terms ''name'' and ''designation''. To the IAU, ''name'' refers to the (usually colloquial) term used for a star in everyday conversation, while ''designation'' is solely alphanumerical, and used almost exclusively in official catalogues and for professional astronomy. (The WGSN notes that transliterated Bayer designations (e.g., Tau Ceti) are considered a special historical case and are treated as designations.) Terms of reference The terms of reference for the WGSN for the period 2016–2018 were approved by the IAU Executive Committee at its meeting on 6 May 2016. In summary, these are to: * establish IAU guidelines for the proposal and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of a star. Yerkes luminosity class IV The term subgiant was first used in 1930 for class G and early K stars with absolute magnitudes between +2.5 and +4. These were noted as being part of a continuum of stars between obvious main-sequence stars such as the Sun and obvious giant stars such as Aldebaran, although less numerous than either the main sequence or the giant stars. The Yerkes spectral classification system is a two-dimensional scheme that uses a letter and number combination to denote the temperature of a star (e.g. A5 or M1) and a Roman numeral to indicate the luminosity relative to other stars of the same temperature. Luminosity class IV stars are the subgiants, located between main-sequence stars (luminosity class&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speckle Interferometry
Speckle imaging comprises a range of high-resolution Astrophotography, astronomical imaging techniques based on the analysis of large numbers of short Exposure (photography), exposures that freeze the variation of Astronomical seeing, atmospheric turbulence. They can be divided into the shift-and-add ("''image stacking''") method and the speckle interferometry methods. These techniques can dramatically increase the Optical resolution, resolution of ground-based telescopes, but are limited to bright targets. Explanation The principle of all the techniques is to take very short exposure images of astronomical targets, and then process those so as to remove the effects of astronomical seeing. Use of these techniques led to a number of discoveries, including thousands of binary stars that would otherwise appear as a single star to a visual observer working with a similar-sized telescope, and the first images of sunspot-like phenomena on other stars. Many of the techniques remain i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, ''e.g.'' Earth around the Sun. Periods in astronomy are expressed in units of time, usually hours, days, or years. Its reciprocal is the orbital frequency, a kind of revolution frequency, in units of hertz. Small body orbiting a central body According to Kepler's Third Law, the orbital period ''T'' of two point masses orbiting each other in a circular or elliptic orbit is: :T = 2\pi\sqrt where: * ''a'' is the orbit's semi-major axis * ''G'' is the gravitationa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopic Binary
A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars using a telescope, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough, they can gravitationally distort each other's outer stellar atmospheres. I ... [...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 ecliptic is divided into four sectors that are associated with the Four Symbols, guardians in Chinese mythology, and further into 28 mansions. Stars around the north celestial pole are grouped into three enclosures (, ''yuán''). The system of 283 asterisms under the 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 S� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upsilon Boötis
Upsilon Boötis is a single, orange-hued star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from υ Boötis, and abbreviated Upsilon Boo or υ Boo. This is a fourth magnitude star that is visible to the naked eye. Based upon an annual parallax shift of as seen from the Earth, it is located about distant. The star is moving closer to the Sun with a radial velocity of −6 km/s. This is an evolved K-type giant star with a stellar classification of K5.5 III. Astroseismology was used to obtain a mass estimate of 1.11 times the mass of the Sun, while interferometric measurements give a size of about 38 times the Sun's radius. It is radiating about 332 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,920 K. The star is roughly 10 billion years old and is spinning with a projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Boötis
Tau Boötis is a wide binary star system in the northern constellation of Boötes. Its name is a Bayer designation that is Latinised from τ Boötis, and abbreviated Tau Boo or τ Boo. This system is visible to the naked eye at a point of light with a combined apparent visual magnitude of 4.50. Based on parallax measurements, It is located at a distance of approximately from the Earth. This system is drifting closer to the Sun with a radial velocity of −16 km/s. The primary component is an ordinary F-type main-sequence star that is larger, brighter, and more massive than the Sun, while the secondary is a faint red dwarf. In 1999, an extrasolar planet was detected orbiting the primary star. Stellar components The primary component is a yellow-white F-type main-sequence star with a stellar classification of F6V. It is 35 percent more massive and 42 percent larger than the Sun. The star is radiating three times the luminosity of the Sun from its photosphere at an ... [...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] |
Neck (Chinese Constellation)
The Neck mansion (亢宿, pinyin: Kàng Sù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the eastern mansions of the Azure Dragon (Chinese constellation), Azure Dragon. In Chinese Cosmology, the Kang Constellation is associated with the Kidney Organ. 亢 is a picture of a person standing with their legs open, as in horse stance, and so holds the quality of strength that comes through a proper foundation. This matches up with Chapter 8 of the Suwen, which says that the Kidney is in charge of strength and fortification. The Kidney houses the Zhi, which is in charge of solid grounding in one’s life purpose. Kang is also the neck or throat of the Azure Dragon of the East, which, while the throat area is ruled by the Lung, has everything to do with sound—pointing to the Kidney’s orifice of the ears. Around the 5th Century BC, it is believed that eclipses would take place in this constellation. This coming together of the Sun and the moon works ... [...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] |
