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BK Camelopardalis
BK Camelopardalis is a variable star in the northern circumpolar constellation of Camelopardalis, near the constellation border with Cassiopeia. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude that fluctuates around 4.74. The star is located approximately 540 light years away from the Sun based on parallax. It is a proposed member of the Cassiopeia–Taurus group of co-moving stars. This is a main sequence Be star with a stellar classification of B2.5 Vne, where the 'n' suffix indicates "nebulous" (broad) lines due to rapid rotation. The presence of emission lines in the spectrum has been known since at least 1895. Spectrograms of the star have been taken since 1905, providing a long history of its cycles of variation. It ranges in brightness from a peak of 4.76 down to 4.90. BK Camelopardalis is 32 million years old and is spinning with a projected rotational velocity of 328 km/s. It has 7.5 times the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camelopardalis (constellation)
Camelopardalis is a large but faint constellation of the celestial sphere, northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars. Etymology First attested in English in 1785, the word ''camelopardalis'' comes from Latin, and it is the romanization of the Greek language, Greek "καμηλοπάρδαλις" meaning "giraffe", from "κάμηλος" (''kamēlos''), "camel" + "πάρδαλις" (''pardalis''), "spotted", because it has a long neck like a camel and spots. Features Stars Although Camelopardalis is the 18th largest constellation, it is not a particularly bright constellation, as the brightest stars are only of fourth magnitude. In fact, it only contains four stars brighter than magnitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-type Main-sequence Stars
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines. Examples include Regulus and Algol A. This class of stars was introduced with the Harvard sequence of stellar spectra and published in the ''Revised Harvard photometry'' catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is 1/5 of the way from type B (or B0) to type A. Later, however, more refined s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Camelopardalis
Alpha Camelopardalis, Latinized from α Camelopardalis, is a star in the northern constellation of Camelopardalis. With an apparent visual magnitude of 4.3, it is the third-brightest star in this not-very-prominent circumpolar constellation; the first and second-brightest stars being Beta Camelopardalis and CS Camelopardalis, respectively. It is the farthest constellational star, with a distance of approximately 6,000 light-years from Earth based on parallax measurements. Description Alpha Camelopardalis has a stellar classification of O9 Ia, with the 'Ia' indicating that it is an O-type luminous supergiant. It is a massive star with 37.6 times the mass of the Sun and 32.5 times the Sun's radius. The effective temperature of the outer envelope is 29,000 K; much hotter than the Sun's effective temperature of 5,778 K, giving it the characteristic blue hue of an O-type star. It is emitting 676,000 times the luminosity of the Sun and is a weak X-ray emitter. Var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
43 Camelopardalis
43 Camelopardalis is a single star in the northern circumpolar constellation of Camelopardalis, located roughly 1,060 light years away from the Sun based on parallax. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 5.11. This object is moving closer to the Earth with a heliocentric radial velocity of −21 km/s. The stellar classification of 43 Camelopardalis is B7 III, matching that of a blue giant. It is spinning rapidly with a projected rotational velocity of 190 km/s. The star has five times the mass of the Sun and about 4.4 times the Sun's radius. It is radiating 724 times the luminosity of the Sun from its photosphere at an effective temperature of 13,183 K. Chinese name In Chinese, (), meaning '' Right Wall of Purple Forbidden Enclosure'', refers to an asterism consisting of 43 Camelopardalis, α Draconis, κ Draconis, λ Draconis, 24 Ursae Majoris, α Camelopardalis and BK Camelopa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
24 Ursae Majoris
24 Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, located 101.5 light-years from the Sun. It has the variable star designation DK Ursae Majoris and the Bayer designation d Ursae Majoris; ''24 Ursae Majoris'' is the Flamsteed designation. This object is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.54. It is moving closer to the Earth with a heliocentric radial velocity of −27 km/s, and is expected to come as close as in around 879,000 years. Description 24 Ursae Majoris has a stellar classification of G4 III-IV, which, at the estimated age of about one billion years, matches the spectrum of an aging giant star blended with features of a subgiant luminosity class. Based upon its position on the H–R diagram, this star has just passed through the Hertzsprung gap and is ready to begin its first ascent along the red-giant branch. It is a suspected RS Canum Venati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda Draconis
Lambda Draconis (λ Draconis, abbreviated Lam Dra, λ Dra), also named Giausar ( ), is a solitary, orange-red star in the northern circumpolar constellation of Draco. It is visible to the naked eye with an apparent visual magnitude of +3.85. Based upon an annual parallax shift of 9.79 mas as seen from the Earth, the star is located around 333 light years from the Sun. This is an evolved red giant star on the asymptotic giant branch with a stellar classification of M0III-IIIa Ca1. It is a suspected slow irregular variable with a periodicity of roughly 1,100 days. The measured angular diameter, after correction for limb darkening, is . At the estimated distance of the star, this yields a physical size of about 53 times the radius of the Sun. It has an estimated 1.7 times the mass of the Sun and is radiating 834 times the solar luminosity from its photosphere at an effective temperature of 3,958 K. Nomenclature λ Draconis ( Latinised to ''Lambda Dr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa Draconis
Kappa Draconis, Latinized from κ Draconis, is a blue giant star located in the northern circumpolar constellation of Draco. At an apparent magnitude of 3.88, it is barely visible to the naked eye when artificial lighting from cities is present. Nevertheless, it is a powerful star, approximately five time as massive as the Sun. It is about 460 light-years away, and is 1,400 times brighter than the Sun. The star is currently located at declination (right ascension ), but due to the effects of precession, Kappa Draconis was the nearest star to the north celestial pole visible to the naked eye from 1793 BC to approximately 1000 BC, though it was 6° removed from perfect alignment, making it only an approximate pole star, similar to the roughly 7° variance from perfect alignment of the much brighter (magnitude 2.08) star Kochab, at the same time during Earth's precession. Properties Kappa Draconis is a classical Be star, displaying Balmer emission lines in its spectrum. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Draconis
Thuban (), with Bayer designation Alpha Draconis or α Draconis, is a binary star system in the northern constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star from the 4th to 2nd millennium BC. Johann Bayer gave Thuban the designation Alpha and placed it as the only member of his ''secundae'' magnitude class in Draco, although its current apparent magnitude of 3.65 means it is 3.7 times fainter than the brightest star in the constellation, Gamma Draconis (Eltanin), which Bayer placed in his ''tertiae'' magnitude class although its current apparent magnitude is 2.24. Nomenclature ''α Draconis'' ( Latinised to ''Alpha Draconis'') is the star's Bayer designation. The traditional name ''Thuban'' is derived from the Arabic word ' ('large snake' (e.g. a python or a legendary draconian serpent)). It is sometimes known as the ''Dragon's Tail'' and as ''Adib'' . In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purple Forbidden Enclosure
The Purple Forbidden enclosure ( Zǐ wēi yuán) is one of the San Yuan ( Sān yuán) or Three Enclosures Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenistic .... Stars and constellations of this group lie near the north celestial pole and are visible all year from temperate latitudes in the Northern Hemisphere. Asterisms The asterisms are : See also * Twenty-eight mansions References Chinese constellations Chinese astrology {{china-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Language
Chinese (, especially when referring to written Chinese) is a group of languages spoken natively by the ethnic Han Chinese majority and many minority ethnic groups in Greater China. About 1.3 billion people (or approximately 16% of the world's population) speak a variety of Chinese as their first language. Chinese languages form the Sinitic branch of the Sino-Tibetan languages family. The spoken varieties of Chinese are usually considered by native speakers to be variants of a single language. However, their lack of mutual intelligibility means they are sometimes considered separate languages in a family. Investigation of the historical relationships among the varieties of Chinese is ongoing. Currently, most classifications posit 7 to 13 main regional groups based on phonetic developments from Middle Chinese, of which the most spoken by far is Mandarin (with about 800 million speakers, or 66%), followed by Min (75 million, e.g. Southern Min), Wu (74 million, e.g. Shangh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionizing Radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
