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Omega1 Scorpii
ω1 Scorpii, Latinised as Omega1 Scorpii, is a star in the zodiac constellation of Scorpius. With an apparent visual magnitude of 3.95 it can be seen with the naked eye, 0.22 degree north of the ecliptic. Parallax measurements of this star give an estimated distance of around 470 light years from the Sun. It is a member of the Scorpius–Centaurus association. This is a B-type main sequence star with a stellar classification of B1 V. It has a luminosity of 9,120 Suns, consistent with an isochronal age of 5 million years and an estimated mass of 11 solar masses. The radius is about 6.6 times that of the Sun. It has an effective temperature of 26,530 in its outer atmosphere. Omega1 Scorpii is a β Cephei star that undergoes non-radial pulsations at a rate of 15 cycles per day. This is causing the surface temperature to fluctuate between 28,300 K and 22,600 K along the equator. The star is spinning rapidly with a projected rotational velocity of 105 km/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bayer Designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. The brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas ''Uranometria''. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers (including Nicolas-Louis de Lacaille and Benjamin Apthorp Gould) supplemented Bayer's catalog with entries for southern constellations. Scheme Bayer assigned a lowercase Greek letter (alpha (α), beta (β), gamma (γ), etc.) or a Latin letter (A, b, c, etc.) to each star he catalogued, combined with the Latin name of the star's parent constellation in genitive (possessive) form. The constellation name is frequently abbreviated to a standard three-letter form. For example, Aldebaran in the constellation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scorpius–Centaurus Association
The Scorpius–Centaurus association (sometimes called Sco–Cen or Sco OB2) is the nearest OB association to the Sun. This stellar association is composed of three subgroups (Upper Scorpius, Upper Centaurus–Lupus, and Lower Centaurus–Crux) and its distance is about 130 parsecs or 420 light-years. Using improved Hipparcos data, Rizzuto and colleagues analysed nearby stars more closely, bringing the number of known members to 436. They doubt the need to add a subclassification because they found a more continuous spread of stars. The Sco–Cen subgroups range in age from 11 million years (Upper Scorpius) to roughly 15 million years (Upper Centaurus–Lupus and Lower Centaurus–Crux). Many of the bright stars in the constellations Scorpius, Lupus, Centaurus, and Crux are members of the Sco–Cen association, including Antares (the most massive member of Upper Scorpius), and most of the stars in the Southern Cross. Hundreds of stars have been identified as members of Sco-Cen, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of 2018, the Union had over 13,700 individual members, spanning 90 countries, and 82 national members. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu2 Scorpii
Mu² Scorpii (μ² Scorpii, abbreviated Mu² Sco, μ² Sco), also named Pipirima , is a star in the zodiac constellation of Scorpius. It has an apparent visual magnitude of +3.56, which is bright enough to be seen with the naked eye. Its distance from the Sun is about 474 light-years, as determined by parallax measurements. It is a member of the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association. Properties This is a blue-white, B-type subgiant star with a stellar classification of B2 IV. It has an estimated 7 times the radius of the Sun, almost 9 times the Sun's mass, and shines with 2,385 times the Sun's luminosity. The outer atmosphere has an effective temperature of 23,113 K. It is some 18.5 million years old and is spinning with a projected rotational velocity of 58 km/s. Nomenclature ''μ² Scorpii'' ( Latinised to ''Mu² Scorpii'') is the star's Bayer designation. In Tahiti, a traditional story is told of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omega2 Scorpii
ω2 Scorpii, Latinised as Omega2 Scorpii, is a suspected variable star in the zodiac constellation of Scorpius. A component of the visual double star ω Scorpii, it is bright enough to be seen with the naked eye having an apparent visual magnitude of +4.320. The distance to this star, as determined using parallax measurements, is around 291 light years. The visual magnitude of this star is reduced by 0.38 because of extinction from interstellar dust. It is 0.05 degree north of the ecliptic, so can be occulted by the moon and planets. This is a G-type giant star with a stellar classification of G6/8III. With an estimated age of 282 million years, it is an evolved, thin disk star that is currently on the red horizontal branch. The interferometry-measured angular diameter of this star is , which, at its estimated distance, equates to a physical radius of nearly 16 times the radius of the Sun. It has 3.27 times the mass of the Sun, and radiates 141 times the Sun's lumi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polynesian Narrative
The Polynesian narrative or Polynesian mythology encompasses the oral traditions of the people of Polynesia (a grouping of Central and South Pacific Ocean island archipelagos in the Polynesian Triangle) together with those of the scattered cultures known as the Polynesian outliers. Polynesians speak languages that descend from a language reconstructed as Proto-Polynesian - probably spoken in the Tonga - Samoa area around 1000 BC. Description Prior to the 15th century AD, Polynesian peoples fanned out to the east, to the Cook Islands, and from there to other groups such as Tahiti and the Marquesas. Their descendants later discovered the islands from Tahiti to Rapa Nui, and later Hawai‘i and New Zealand. The latest research puts the settlement of New Zealand at about 1300 AD. The various Polynesian languages are all part of the Austronesian language family. Many are close enough in terms of vocabulary and grammar to permit communication between some other language speakers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cook Islands
) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , languages_type = Spoken languages , languages = , ethnic_groups = , ethnic_groups_year = 2016 census , demonym = Cook Islander , government_type = , leader_title1 = Monarch , leader_name1 = , leader_title2 = 's Representative , leader_name2 = Sir Tom Marsters , leader_title3 = Prime Minister , leader_name3 = Mark Brown , leader_title4 = President of the House of Ariki , leader_name4 = Tou Travel Ariki , legislature = Parliament , sovereignty_type = Associated state of New Zealand , established_event1 = Self-governance , established_date1 = 4 August 1965 , establi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 bulge due to centrifugal force. As stars are not solid bodies, they can also undergo differential rotation. Thus the equator of the star can rotate at a different angular velocity than the higher latitudes. These differences in the rate of rotation within a star may have a significant role in the generation of a stellar magnetic field. The magnetic field of a star interacts with the stellar wind. As the wind moves away from the star its rate of angular velocity slows. The magnetic field of the star interacts with the wind, which applies a drag to the stellar rotation. As a result, angular momentum is transferred from the star to the wind, and over time this gradually slows the star's rate of rotation. Measurement Unless a star is being obse ... [...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] |
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, including 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 straightf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of the Sun. This equates to about two nonillion (short scale), two quintillion (long scale) kilograms or 2000 quettagrams: The solar mass is about times the mass of Earth (), or times the mass of Jupiter (). History of measurement The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance. The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of the Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of (9 arcseconds, compared to the present value of ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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