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2MASS J18082002−5104378
2MASS J18082002−5104378 (abbreviated J1808−5104) is an ultra metal-poor (UMP) Binary star, binary star system, in the constellation Ara (constellation), Ara, about from Earth, and is a Binary star#Spectroscopic binaries, single-lined spectroscopic binary (SB1). It is one of the oldest stars known, about 13.53 billion years old, possibly one of the first stars, a star made almost entirely of materials released from the Big Bang. A tiny unseen companion, a low-mass UMP star, is particularly unusual. System J1808−5104 is an ultra metal-poor (UMP) star, one that has a Logarithmic scale, logarithmic metallicity [Fe/H] less than , or th of the levels in the Sun. It is a single-lined spectroscopic binary, with radial velocity variations in its spectral absorption lines interpreted as orbital motion of the visible star. The companion is invisible, but inferred from the orbit. J1808−5104 is the brightest UMP star, as a binary system, known, and is part of the ... [...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] |
Galaxy
A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarf galaxy, dwarfs with less than a thousand stars, to the List of largest galaxies, largest galaxies known – Type-cD galaxy, supergiants with one hundred 10^12, trillion stars, each orbiting its galaxy's centre of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few per cent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorised according to their visual morphology (astronomy), morphology as elliptical galaxy, elliptical, Spiral galaxy, spiral, or irregular galaxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
November 2018
Events January * January 1 – Bulgaria takes over the Presidency of the Council of the European Union, after the Estonian presidency. * January 4 – SPLM-IO rebels loyal to Chan Garang Lual start a raid against Juba, capital of South Sudan. * January 12– 13 – The first round of voting in the 2018 Czech presidential election is held. * January 20 – Turkey, led by President Recep Tayyip Erdoğan, announces the beginning of a military offensive to capture a portion of northern Syria from Kurdish forces, amidst the ongoing Kurdish–Turkish conflict. * January 20– 22 – The US government enters a federal government shutdown as a result of a dispute over Deferred Action for Childhood Arrivals. * January 24 – Scientists in China report in the journal ''Cell'' the creation of the first monkey clones using somatic cell nuclear transfer, named Zhong Zhong and Hua Hua. * January 26– 27 – The second round of voting of the 2018 Czech presidential election is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
