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Nu Horologii
Nu Horologii, Latinized from ν Horologii, is the Bayer designation for a single star in the southern constellation of Horologium. It was catalogued by the Dutch explorer Frederick de Houtman in 1603. With an apparent visual magnitude of 5.3, this star can be seen with the naked eye from the southern hemisphere. (According to the Bortle scale, it can be seen at night from bright suburban skies.) Based upon parallax, Nu Horologii lies at a distance of 169 light-years from Earth. It is drifting closer to the Sun with a radial velocity of +31 km/s. Physical characteristics The stellar classification of A2 V indicates that it is an A-type main sequence star that is generating energy through thermonuclear fusion of hydrogen into helium at its core. Nu Horologii is larger and hotter than the Sun, with 190% of the Sun's mass, 188% of the radius of the Sun, and it shines with 16.7 times the solar luminosity. This is a young star with an estimated age of 540 mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horologium (constellation)
Horologium (Latin , the pendulum clock, from Ancient Greek, Greek , ) is a constellation of six stars faintly visible in the southern celestial hemisphere. It was first described by the French astronomer Nicolas-Louis de Lacaille in 1756 and visualized by him as a clock with a pendulum and a second hand. In 1922 the constellation was redefined by the International Astronomical Union (IAU) as a region of the celestial sphere containing Lacaille's stars, and has since been an IAU designated constellations, IAU designated constellation. Horologium's associated region is wholly visible to observers south of 23rd parallel north, 23°N. The constellation's brightest star—and the only one brighter than an apparent magnitude of 4—is Alpha Horologii (at 3.85), an aging orange giant star that has swollen to around 11 times the diameter of the Sun. The Mira variable, long-period variable-brightness star, R Horologii (4.7 to 14.3), has one of the largest variations in brightness among al ... [...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. In its turn, the magnetic field of a star interacts with the stellar wind. As the wind moves away from the star its angular speed decreases. 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 sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-type Main-sequence Stars
A type or type A may refer to: Science * A-type asteroid, a type of relatively uncommon inner-belt asteroids * A type blood, a type in the ABO blood group system * A-type inclusion, a type of cell inclusion * A-type potassium channel, a type of voltage-gated potassium channel * A type proanthocyanidin, a specific type of flavonoids * A-type star, a class of stars * Type A climate, a type in the Köppen climate classification * Type A flu, a type of influenza virus * Type A evaluation of uncertainty, an uncertainty in measurement that can be inferred, for example, from repeated measurement * Type A personality, a personality type in the Type A and Type B personality theory * Hemophilia type A, a type of haemophilia * A-type granite a type of granite rock * Adenosine receptor Technology * Type A Dolby Noise Reduction, a type of Dolby noise-reduction system * Type A plug (see also NEMA connector) * Type A submarine, a class of submarines in the Imperial Japanese Navy which served during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commonwealth Scientific And Industrial Research Organisation
The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations around the world. From its headquarters in Canberra, CSIRO maintains more than 50 sites across Australia as well as in France and the United States, employing over 6,500 people. Federally funded scientific research in Australia began in 1916 with the creation of the Advisory Council of Science and Industry. However, the council struggled due to insufficient funding. In 1926, research efforts were revitalised with the establishment of the Council for Scientific and Industrial Research (CSIR), which strengthened national science leadership and increased research funding. CSIR grew rapidly, achieving significant early successes. In 1949, legislative changes led to the renaming of the organisation as Commonwealth Scientific and Industrial Research ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Society Of The Pacific
The Astronomical Society of the Pacific (ASP) is an American scientific and educational organization, founded in San Francisco on February 7, 1889, immediately following the solar eclipse of January 1, 1889. Its name derives from its origins on the Pacific Coast, but today it has members all over the country and the world. It has the legal status of a nonprofit organization. It is the largest general astronomy education society in the world, with members from over 40 countries. Education and outreach programs The ASP's mission is to promote public interest in and awareness of astronomy (and increase scientific literacy) through its publications, web site, and many educational and outreach programs. * The NASA Night Sky Network – a community of more than 450 astronomy clubs across the U.S. that share their time and telescopes to engage the public with unique astronomy experiences. The ASP provides training and materials to enhance clubs outreach activities, and inspires more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding the nucleus, and sometimes a Comet tail, tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can Subtended angle, subtend an arc of up to 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oort Cloud
The Oort cloud (pronounced or ), sometimes called the Öpik–Oort cloud, is scientific theory, theorized to be a cloud of billions of Volatile (astrogeology), icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 Astronomical unit, AU (0.03 to 3.2 light-years). The cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of Comet, long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun. The cloud is thought to encompass two regions: a circumstellar disc, disc-shaped inner Oort cloud aligned with the Ecliptic, solar ecliptic (also called its Hills cloud) and a circumstellar envelope, spherical outer Oort cloud enclosing the entire Solar System. Both regions lie well beyond the heliosphere and are in Outer space#Interstellar space, interstellar space. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Fornacis
Alpha Fornacis (α Fornacis, abbreviated Alpha For, α For) is a triple star system in the southern constellation of Fornax. It is the brightest star in the constellation and the only one brighter than magnitude 4.0. Based on parallax measurements obtained during the Gaia mission, it is 45.66 light-years distant. Its three components are designated Alpha Fornacis A (officially named Dalim ), Alpha Fornacis Ba and Alpha Fornacis Bb. Nomenclature ''α Fornacis'' ( Latinised to ''Alpha Fornacis'') is the system's Bayer designation. The designations of the three components as ''Alpha Fornacis A, Ba and Bb'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). Formerly it was designated as the 12th of Eridanus (12 Eri) by Flamsteed. Indigenous Arabs had named both Alpha Eridani and Fomalhaut ظَلِيم ''al-ẓalīm'', a local word for 'ostrich'. Later, Arabi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debris Disk
A debris disk (American English), or debris disc ( Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks are found around stars with mature planetary systems, including at least one debris disk in orbit around an evolved neutron star. Debris disks can also be produced and maintained as the remnants of collisions between planetesimals, otherwise known as asteroids and comets. As of 2001, more than 900 candidate stars had been found to possess a debris disk. They are usually discovered by examining the star system in infrared light and looking for an excess of radiation beyond that emitted by the star. This excess is inferred to be radiation from the star that has been absorbed by the dust in the disk, then re-radiated away as infrared energy. Debris disks are often described as massive analogs to the debris in the Solar System. Most kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared Excess
An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are often the result of circumstellar dust heated by starlight and reemitted at longer wavelengths. They are common in young stellar objects and evolved stars on the asymptotic giant branch or older. In addition, monitoring for infrared excess emission from stellar systems is one possible method that could enable a search for large-scale stellar engineering projects of a hypothetical extraterrestrial civilization; for example a Dyson sphere A Dyson sphere is a hypothetical megastructure that encompasses a star and captures a large percentage of its power output. The concept is a thought experiment that attempts to imagine how a spacefaring civilization would meet its energy re ... or Dyson swarm. This infrared excess would be the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. One au is approximately equivalent to 499 light-seconds. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical unit. In the astronomical literature, the symbol AU is common. In 2006, the International Bureau of Weights and Measures (BIPM) had recommended ua as the symbol for the unit, from the French ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big enough to sustain nuclear fusion of hydrogen into helium in their cores, but massive enough to emit some light and heat from the deuterium fusion, fusion of deuterium (deuterium, 2H). The most massive ones (> ) can lithium burning, fuse lithium (lithium-7, 7Li). Astronomers classify self-luminous objects by Stellar classification#Spectral types, spectral type, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M (2100–3500 Kelvin, K), L (1300–2100 Kelvin, K), T (600–1300 Kelvin, K), and Y ( 80 ''M''J), which have spectral classes L2 to L6. Spectral class T As GD 165B is the prototype of the L dwarfs, Gliese 229B is the prototype of a second ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
