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SCR 1845−6357
SCR 1845−6357 is a binary system, away in the constellation Pavo. The primary is a low-mass red dwarf and the secondary is a brown dwarf. It is one of the nearest stellar systems, as well as the closest red dwarf-brown dwarf binary. System The primary, SCR 1845−6357A, is an ultra-cool red dwarf, one of the smallest and coolest stars so far discovered, with a mass of about 7% of the Sun's, a radius 9.4% of the Sun's, and an effective temperature of . It is very faint, at an apparent magnitude of 17.4 due to its low luminosity, equivalent to 0.03% of the Sun's luminosity across all wavelengths. It was discovered in 2004 by the SuperCOSMOS survey. This star has been found to have a brown dwarf companion in 2006, designated . The companion has an observed distance of 4.1 AU from the primary and is classified as a T-dwarf. It is estimated to have 25 to 65 times the mass of Jupiter (2.4 to 6.2% of the Sun's mass), but its radius is 30% smaller than that of Ju ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pavo (constellation)
Pavo is a constellation in the Southern Celestial Hemisphere, southern sky whose name is Latin for . Pavo first appeared on a 35-cm (14 in) diameter celestial globe published in 1598 in Amsterdam by Petrus Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas ''Uranometria'' of 1603, and was likely conceived by Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. French explorer and astronomer Nicolas-Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Pavo, Grus (constellation), Grus, Phoenix (constellation), Phoenix and Tucana are collectively known as the "Southern Birds". The constellation's brightest member, Alpha Pavonis, is also known as Peacock and appears as a 1.91-Apparent magnitude, magnitude blue-white star, but is actually a spectroscopic binary. Delta Pavonis is a nearby Sun-like star some 19.9 light-years distant. Six of the star systems in Pavo have been found to host planets, inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminosity
Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object, astronomical objects. In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the Solar luminosity, luminosity of the Sun, ''L''⊙. Luminosity can also be given in terms of the astronomical Magnitude (astronomy), magnitude system: the Absolute magnitude#Bolometric magnitude, absolute bolometric magnitude (''M''bol) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or Passband, filter band. In contrast, the term ''brightness'' in astronomy is gene ... [...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] |
VizieR
A vizier (; ; ) is a high-ranking political advisor or Minister (government), minister in the Near East. The Abbasids, Abbasid caliphs gave the title ''wazir'' to a minister formerly called ''katib'' (secretary), who was at first merely a helper but afterwards became the representative and successor of the ''dapir'' (official scribe or secretary) of the Sasanian Empire, Sassanian kings. In modern usage, the term has been used for government Minister (government), ministers in much of the Middle East and beyond. Several alternative spellings are used in English, such as ''vizir'', ''wazir'', and ''vezir''. Etymology Vizier may be derived from the Arabic ''wazara'' (), from the Semitic root ''W-Z-R''. The word is mentioned in the Quran, where Aaron is described as the ''wazir'' (helper) of Moses, as well as the word ''wizr'' (burden) which is also derived from the same root. It was later adopted as a title, in the form of ''wazīr āl Muḥammad'' () by the proto-Shi'a leaders ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Astrophysical Journal
''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 Publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Astronomical Journal
''The Astronomical Journal'' (often abbreviated ''AJ'' in scientific papers and references) is a peer-reviewed monthly scientific journal owned by the American Astronomical Society (AAS) and currently published by IOP Publishing. It is one of the premier journals for astronomy in the world. Until 2008, the journal was published by the University of Chicago Press on behalf of the AAS. The reasons for the change to the IOP were given by the society as the desire of the University of Chicago Press to revise its financial arrangement and their plans to change from the particular software that had been developed in-house. The other two publications of the society, the ''Astrophysical Journal'' and its supplement series, followed in January 2009. The journal was established in 1849 by Benjamin A. Gould. It ceased publication in 1861 due to the American Civil War, but resumed in 1885. Between 1909 and 1941 the journal was edited in Albany, New York. In 1941, editor Benjamin Boss arranged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy & 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] |
Cha 110913−773444
Cha 110913−773444 (sometimes abbreviated ''Cha 110913'') is an astronomical object surrounded by what appears to be a protoplanetary disk. It lies at a distance of 529 light-years from Earth. There is no consensus yet among astronomers whether to classify the object as a sub-brown dwarf (with planets) or a rogue planet (with moons). Cha 110913−773444 was discovered in 2004 by Kevin Luhman and others at Pennsylvania State University using the Spitzer Space Telescope and the Hubble Space Telescope, as well as two Earth-bound telescopes in Chile. See also * WISEA J120037.79-784508.3, a brown dwarf with a primordial disk * OTS 44, a rogue planet * SCR 1845-6357, a binary system with a faint red dwarf and a brown dwarf * PSO J318.5−22, a rogue planet * 2MASS J11151597+1937266, a relative nearby planetary-mass object with a disk * KPNO-Tau 12 KPNO-Tau 12 (also called 2MASS J0419012+280248) is a low-mass brown dwarf or free-floating planetary-mass object ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OTS 44
OTS 44 is a free-floating planetary-mass object or brown dwarf located at in the constellation Chamaeleon near the reflection nebula IC 2631. It is among the lowest-mass free-floating substellar objects, with approximately 11.5 times the mass of Jupiter, or approximately 1.1% that of the Sun. Its radius is estimated to be 3.2 or 3.6 times that of Jupiter. OTS 44 was discovered in 1998 by Oasa, Tamura, and Sugitani as a member of the star-forming region Chamaeleon I. Based upon infrared observations with the Spitzer Space Telescope and the Herschel Space Observatory, OTS 44 emits an excess of infrared radiation for an object of its type, suggesting it has a circumstellar disk of dust and particles of rock and ice. This disk (gas+dust) has a SED-fitted mass of at about 30 Earth masses. Observations with the SINFONI spectrograph at the Very Large Telescope show that the disk is accreting matter at the rate of approximately 10−11 of the mass of the Sun per year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter Radius
The Jupiter radius or Jovian radius ( or ) has a value of , or 11.2 Earth radii () (one Earth radius equals ). The Jupiter radius is a unit of length used in astronomy to describe the radii of gas giants and some exoplanets. It is also used in describing brown dwarfs. The general shape of the planet Jupiter has been directly measured from radio occultations of passing spacecraft, starting with the Pioneer and Voyager missions. This gives an overall margin of error of about 5 km. Estimates of the radii at one bar pressure are then determined through extrapolation. The planet Jupiter has the approximate shape of an oblate spheroid, which is mainly set by the rate of rotation. This gives a difference of about 10% between the polar and equatorial radii. The polar radius has been determined with an accuracy of ±10 km, as of 1987. Density fluctuations within the planet can create variations in the equatorial radius of up to 30 km. The winds in the outer atmosphere can v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Of Jupiter
The Jupiter mass, also called Jovian mass, is the units of mass, unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter is by far the most giant planet, massive planet in the Solar System. It is approximately 2.5 times as massive as all of the other planets in the Solar System combined. Jupiter mass is a common unit of mass in astronomy that is used to indicate the masses of other similarly-sized objects, including the outer planets, extrasolar planets, and brown dwarfs, as this unit provides a convenient scale for comparison. Current best estimates The current best known value for the mass of Jupiter can be expressed as : M_\mathrm=(1.89813 \pm 0.00019)\times10^ \text, which is about as massive as the Sun (is about ): M_\mathrm=\frac M_ \approx (9.547919 \pm 0.000002) \times10^ M_. Jupiter is 318 times as massive as Earth: M_\mathrm = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-dwarf
An object with the spectral type T (also called T dwarf or methane brown dwarf) is either a brown dwarf or young free-floating planetary-mass object. A directly imaged exoplanet with a young age can also be a T-dwarf. T dwarfs are colder than L dwarfs, but warmer than Y dwarfs. Prototype Gliese 229B The first T-dwarf discovered was Gliese 229B, which was discovered in 1995. This object had a temperature below 1000 K and showed methane (CH4), water vapor (H2O) and carbon monoxide (CO) in its spectrum. In the upper atmosphere CO is converted into CH4 and H2O, while the opposite is true for the hotter lower atmosphere. It also showed absorption due to caesium (Cs), but absorption features commonly found in M-dwarfs ( CaH, FeH, TiO, and VO) were missing. Ammonia (NH3) was included in the analysis of the spectrum. Sodium (Na) and potassium (K) are also detected in this T-dwarf. Later work found a dynamical mass of 70 ± 5 for Gliese 229B, which is much higher than the cooling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
