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HD 74156
HD 74156 is a yellow dwarf star (spectral type G0V) in the constellation of Hydra, 187 light years from the Solar System. It is known to be orbited by two giant planets. Star This star is 24% more massive and 64% larger than the Sun. The total luminosity is 2.96 times that of the Sun and its temperature 5960 K. The age of the star is estimated at 3.7 billion years, with metallicity 1.35 times that of the Sun based on its abundance of iron. Planetary system In April 2001, two giant planets were announced orbiting the star. The first planet HD 74156 b orbits the star at a distance closer than Mercury is to the Sun, in an extremely eccentric orbit. The second planet HD 74156 c is a long-period, massive planet (at least 8 times the mass of Jupiter), which orbits the star in an elliptical orbit with a semimajor axis of 3.90 astronomical units. In 2022, the inclination and true mass of HD 74156 c were measured via astrometry. Claims of a third planet Given the two-plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Draper Catalogue
The ''Henry Draper Catalogue'' (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the ''Henry Draper Extension'' (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the ''Henry Draper Extension Charts'' (HDEC), published from 1937 to 1949 in the form of charts, which gave classifications for 86,933 more stars. In all, 359,083 stars were classified as of August 2017. The HD catalogue is named after Henry Draper, an amateur astronomer, and covers the entire sky almost completely down to an apparent photographic magnitude of about 9; the extensions added fainter stars in certain areas of the sky. The construction of the ''Henry Draper Catalogue'' was part of a pioneering effort to classify stellar spectra, and its catalogue numbers are commonly used as a way of identifying stars. History The origin of the ''Henry Draper Catalogue'' d ... [...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] |
Extrasolar Planets Encyclopaedia
The Extrasolar Planets Encyclopaedia (also known as Encyclopaedia of exoplanetary systems and Catalogue of Exoplanets) is an astronomy website, founded in Paris, France at the Meudon Observatory by Jean Schneider in February 1995, which maintains a database of all the currently known and candidate extrasolar planets, with individual pages for each planet and a full list interactive catalog spreadsheet. The main catalogue comprises databases of all of the currently confirmed extrasolar planets as well as a database of unconfirmed planet detections. The databases are frequently updated with new data from peer-reviewed publications and conferences. In their respective pages, the planets are listed along with their basic properties, including the year of planet's discovery, mass, radius, orbital period, semi-major axis, eccentricity, inclination, longitude of periastron, time of periastron, maximum time variation, and time of transit, including all error range values. The ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Astrophysical Journal Supplement Series
''The Astrophysical Journal'' (''ApJ'') is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and became an electronic-only journal in 2015. Since 1953, ''The Astrophysical Journal Supplement Series'' (''ApJS'') has been published in conjunction with ''The Astrophysical Journal'', with generally longer articles to supplement the material in the journal. It publishes six volumes per year, with two 280-page issues per volume. ''The Astrophysical Journal Letters'' (''ApJL''), established in 1967 by Subrahmanyan Chandrasekhar as Part 2 of ''The Astrophysical Journal'', is now a separate journal focusing on the rapid publication of high-impact astronomical research. The three journals were published by the University of Chicago Press for the American Astronomical Society until, in January 2009, publication was transferred to IOP Publi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy And Astrophysics
''Astronomy & Astrophysics (A&A)'' is a monthly peer-reviewed scientific journal covering theoretical, observational, and instrumental astronomy and astrophysics. It is operated by an editorial team under the supervision of a board of directors representing 27 sponsoring countries plus a representative of the European Southern Observatory. The journal is published by EDP Sciences and the current editors-in-chief are Thierry Forveille and João Alves. History Origins ''Astronomy & Astrophysics'' was created as an answer to the publishing situation found in Europe in the 1960s. At that time, multiple journals were being published in several countries around the continent. These journals usually had a limited number of subscribers, and articles were written in languages other than English. They were less widely read than American and British journals and the research they reported had therefore less impact in the community. Starting in 1963, conversations between astronomers from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monthly Notices Of The Royal Astronomical Society
''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal in astronomy, astrophysics and related fields. It publishes original research in two formats: papers (of any length) and letters (limited to five pages). MNRAS publishes more articles per year than any other astronomy journal. The learned society journal has been in continuous existence since 1827 and became online only in 2020. It operates as a partnership between the Royal Astronomical Society (RAS), who select and peer-review the contents, and Oxford University Press (OUP), who publish and market the journal. Despite its name, MNRAS is no longer monthly, nor does it carry the notices of the RAS. In 2024 MNRAS became a purely gold open access journal. History The first issue of MNRAS was published on 9 February 1827 as ''Monthly Notices of the Astronomical Society of London'' and it has been in continuous publication ever since. It took its current name from the second vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upsilon Andromedae
Upsilon Andromedae (υ Andromedae, abbreviated Upsilon And, υ And) is a binary star located 44 light-years from Earth in the constellation of Andromeda. The system consists of an F-type main-sequence star (designated υ Andromedae A, officially named Titawin in the Amazigh language ) and a smaller red dwarf. , three extrasolar planets (designated Upsilon Andromedae b, c, d; named Saffar, Samh and Majriti, respectively) are believed to orbit υ Andromedae A. All three are likely to be jovian planets that are comparable in size to Jupiter. This was both the first multiple- planet system to be discovered around a main-sequence star, and the first multiple-planet system known in a multiple-star system. Nomenclature ''υ Andromedae'' ( Latinised to ''Upsilon Andromedae'') is the system's Bayer designation. Under the rules for naming objects in binary star systems, the two components are designated A and B. Under the same rules, the first planet discovered orbiting υ And ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 37124
HD 37124 is a star in the equatorial constellation of Taurus (the Bull), positioned about a half degree to the SSW of the bright star Zeta Tauri. The apparent visual magnitude of this star is 7.68, which is too dim to be visible to the naked eye. It is located at a distance of 103 light years from the Sun based on parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ..., but is drifting closer with a radial velocity of −23 km/s. Three extrasolar planets have been found to orbit the star. The stellar classification of HD 37124 is G4IV-V, showing a spectrum with blended traits of a main sequence star and a more stellar evolution, evolved subgiant star. It is a Magnetic activity, quiet star with a low Chromospheric activity index, activity index. This star is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Extrasolar Planets
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, but lists are frequently written down on paper, or maintained electronically. Lists are "most frequently a tool", and "one does not ''read'' but only ''uses'' a list: one looks up the relevant information in it, but usually does not need to deal with it as a whole".Lucie Doležalová,The Potential and Limitations of Studying Lists, in Lucie Doležalová, ed., ''The Charm of a List: From the Sumerians to Computerised Data Processing'' (2009). Purpose It has been observed that, with a few exceptions, "the scholarship on lists remains fragmented". David Wallechinsky, a co-author of '' The Book of Lists'', described the attraction of lists as being "because we live in an era of overstimulation, especially in terms of information, and lists help us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Resolution Echelle Spectrometer
The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and, when completed in 1993 (Keck I) and 1996 (Keck II), they were the largest optical reflecting telescopes in the world. They have been the third and fourth largest since 2006. Overview With a concept first proposed in 1977, telescope designers Terry Mast, of the University of California, Berkeley, and Jerry Nelson of Lawrence Berkeley Laboratory had been developing the technology necessary to build a large, ground-based telescope. In 1985, Howard B. Keck of the W. M. Keck Foundation gave $70 million to fund the construction of the Keck I telescope, which began in September 1985. First light occurred on November 24, 1990, using 9 of the eventual 36 segments. When construction of the first telescope was well advanced, further donations allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * Circular orbit: * Elliptic orbit: * Parabolic trajectory: * Hyperbolic trajectory: The eccentricity is given by e = \sqrt where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
