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Lambda Andromedae
Lambda Andromedae, Latinized from λ Andromedae, is the Bayer designation for a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately from Earth, it has an apparent visual magnitude of +3.8. This is bright enough to be seen with the naked eye. The system is drifting further away from the Sun with a radial velocity of +6.8 km/s. Properties Lambda Andromedae is a single-lined spectroscopic binary with an orbital period of 20.5212 days. The spectrum of the primary matches a stellar classification of G8 III-IV, suggesting that it is an evolved star that lies part way between the subgiant and giant stages. The mass of this star is similar to the Sun, but it has expanded to around seven times the Sun's radius. It is radiating over 28 times the luminosity of the Sun from its outer envelope at an effective temperature of 4,800 K, giving it the characteristic yellow hue of a G-type star. This is an RS Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andromeda (constellation)
Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux. Its brightest star, Alpha Andromedae, is a binary star that has also been counted as a part of Pegasus, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. Overview The stellar atmosphere is divided into several regions of distinct character: * The photosphere, which is the atmosphere's lowest and coolest layer, is normally its only visible part. Light escaping from the surface of the star stems from this region and passes through the higher layers. The Sun's photosphere has a temperature in the 5,770 K to 5,780 K range. Starspots, cool regions of disrupted magnetic field lie on the photosphere. * Above the photosphere lies the chromosphere. This part of the atmosphere first cools down and then starts to heat up to about 10 times the temperature of the photosphere. * Above the chromosphere lies the transition region, where the temperature increases rapidly on a distance of only around 100 km. * The outermost part of the stellar atmosphere is the corona, a tenuous plasma which has a tem ... [...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] |
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] |
Lambda Andromedae
Lambda Andromedae, Latinized from λ Andromedae, is the Bayer designation for a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately from Earth, it has an apparent visual magnitude of +3.8. This is bright enough to be seen with the naked eye. The system is drifting further away from the Sun with a radial velocity of +6.8 km/s. Properties Lambda Andromedae is a single-lined spectroscopic binary with an orbital period of 20.5212 days. The spectrum of the primary matches a stellar classification of G8 III-IV, suggesting that it is an evolved star that lies part way between the subgiant and giant stages. The mass of this star is similar to the Sun, but it has expanded to around seven times the Sun's radius. It is radiating over 28 times the luminosity of the Sun from its outer envelope at an effective temperature of 4,800 K, giving it the characteristic yellow hue of a G-type star. This is an RS Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Magnetic Field
A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star. This motion is created through convection, which is a form of energy transport involving the physical movement of material. A localized magnetic field exerts a force on the plasma, effectively increasing the pressure without a comparable gain in density. As a result, the magnetized region rises relative to the remainder of the plasma, until it reaches the star's photosphere. This creates starspots on the surface, and the related phenomenon of coronal loops. Measurement The magnetic field of a star can be measured by means of the Zeeman effect. Normally the atoms in a star's atmosphere will absorb certain frequencies of energy in the electromagnetic spectrum, producing characteristic dark absorption lines in the spectrum. When the atoms are within a magnetic field, however, these lines become split into multiple, closely spaced lines. The energy also becomes polarized ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ROSAT
ROSAT (short for Röntgensatellit; in German X-rays are called Röntgenstrahlen, in honour of Wilhelm Röntgen) was a German Aerospace Center-led satellite X-ray telescope, with instruments built by West Germany, the United Kingdom and the United States. It was launched on 1 June 1990, on a Delta II rocket from Cape Canaveral, on what was initially designed as an 18-month mission, with provision for up to five years of operation. ROSAT operated for over eight years, finally shutting down on 12 February 1999. In February 2011, it was reported that the satellite was unlikely to burn up entirely while re-entering the Earth's atmosphere due to the large amount of ceramics and glass used in construction. Parts as heavy as could impact the surface. ROSAT eventually re-entered the Earth's atmosphere on 23 October 2011 over Bay of Bengal. Overview According to NASA, the Roentgensatellit (ROSAT) was a joint German, U.S. and British X-ray astrophysics project. ROSAT carried a Germa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
