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CS22892-052 (star)
BPS CS22892-0052 (Sneden's Star) is an old population II star located at a distance of 4.7 kpc in the galactic halo. It belongs to a class of ultra-metal-poor stars ( Metallicity e/H-3.1), specifically the very rare subclass of neutron-capture ( r-process) enhanced stars. It was discovered by Tim C. Beers and collaborators with the Curtis Schmidt telescope at the Cerro Tololo Inter-American Observatory in Chile. Extended high-resolution spectroscopic observations since around 1995 (with Chris Sneden from the University of Texas at Austin as the leading observer) allowed observers to determine the abundances of 53 chemical elements in this star, as of December 2005 only second in number to the Sun. From barium (Z=56) on, all elements show the pattern of the r-process contribution to the abundances of the elements in the Solar System. Comparing the observed abundances for a stable element such as europium (Z=63) and the radioactive element thorium (Z=90) to calcul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquarius (constellation)
Aquarius is an celestial equator, equatorial constellation of the zodiac, between Capricornus and Pisces (constellation), Pisces. Its name is Latin for "water-carrier" or "cup-carrier", and its old astronomical symbol is (♒︎), a representation of water. Aquarius is one of the oldest of the recognized constellations along the zodiac (the Sun's apparent path). It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is found in a region often called the Sea (astronomy), Sea due to its profusion of constellations with watery associations such as Cetus the whale, Pisces (constellation), Pisces the fish, and Eridanus (constellation), Eridanus the river. At apparent magnitude 2.9, Beta Aquarii is the brightest star in the constellation. History and mythology Aquarius is identified as "The Great One" in the Babylonian star catalogues and represents the god Ea (god), Ea himself, who is commonly depic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Texas At Austin
The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,075 graduate students and 3,133 teaching faculty as of Fall 2021, it is also the largest institution in the system. It is ranked among the top universities in the world by major college and university rankings, and admission to its programs is considered highly selective. UT Austin is considered one of the United States's Public Ivies. The university is a major center for academic research, with research expenditures totaling $679.8 million for fiscal year 2018. It joined the Association of American Universities in 1929. The university houses seven museums and seventeen libraries, including the LBJ Presidential Library and the Blanton Museum of Art, and operates various auxiliary research facilities, such as the J. J. Pickle Research Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BD+17°3248
BD+17°3248 is an old Population II star located at a distance of roughly in the Galactic Halo. It belongs to the class of ultra-metal-poor stars, especially the very rare subclass of neutron-capture (r-process) enhanced stars. Since about 2000, this star had been studied with 3 telescopes: a) the Hubble Space Telescope, b) the Keck I telescope and c) the Harlan J. Smith Telescope at the McDonald Observatory of the University of Texas. Elemental abundances in the range from germanium (Z=32) up to uranium (Z=92) were determined. The Hubble Space Telescope was used to observe the ultraviolet part of the stellar spectra. This allowed the measurement of platinum, osmium and, for the first time outside of the Solar System, gold. From barium (Z=56) onward, all elements show a pattern of r-process contribution to the abundances of the elements in the Solar system. The University of Mainz and University of Basel groups of Karl-Ludwig Kratz and Friedrich-Karl Thielemann perfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CS31082-001 (star)
BPS CS31082-0001, named Cayrel's Star , is an old Population II star located in a distance of 2.1 kpc in the galactic halo. It belongs to the class of ultra-metal-poor stars (metallicity H">Iron">Fe<_a>_Hydrogen.html" ;"title="Iron.html" ;"title="/nowiki>Iron">Fe/Hydrogen">H/nowiki> = -2.9), specifically the very rare subclass of neutron-capture enhanced stars. It was discovered by Tim C. Beers and collaborators with the Curtis Schmidt telescope at the Cerro Tololo Inter-American Observatory in Chile and analyzed by Roger Cayrel and collaborators. They used the Very Large Telescope ( Very Large Telescope, VLT) at the European Southern Observatory in Paranal, Chile for high-resolution optical spectroscopy to determine elemental abundances. The thorium-232 to uranium-238 ratio was used to determine the age. It is estimated to be about 12.5 billion years old, making it one of the oldest known. Compared to other ultra-metal-poor, r-process enriched st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich-Karl Thielemann
Friedrich-Karl "Friedel“ Thielemann (born 17 April 1951 in Mülheim an der Ruhr) is a German-Swiss theoretical astrophysicist. Thielemann studied at the TH Darmstadt, where he in 1976 he acquired his Diplom. In 1980 he earned his PhD under Wolfgang Hillebrandt (in Garching) and E. R. Hilf in nuclear astrophysics. As a post-doc he was with David Schramm and William David Arnett at the University of Chicago, William A. Fowler at Caltech, Hans Klapdor at the Max-Planck-Institut für Kernphysik, am Max-Planck-Institut für Astrophysik in Garching (with Hillebrandt) and at the University of Illinois (with James W. Truran). Starting in 1986 he was Assistant Professor and from 1991 Associate Professor at the Center for Astrophysics Harvard & Smithsonian and at the Harvard Observatory of Harvard University. In 1994 he became a professor at the University of Basel. In 1995 he was a guest professor at the University of Turin and from 1997 to 2001 a guest scientist at Oak Ridge Natio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karl-Ludwig Kratz
Karl-Ludwig Kratz (born April 23, 1941, in Jena, Thuringia) is a German nuclear chemist and astrophysicist. He is professor for nuclear chemistry at the Johannes Gutenberg University of Mainz and adjunct professor of physics at the University of Notre Dame in South Bend, Indiana. One of the main interests of Kratz is the study of nuclear structure of very neutron-rich isotopes. He concentrated on the beta-delayed neutron decay mode, especially the spectroscopy of the emitted neutrons. These isotopes are obtained by nuclear fission or proton induced spallation of heavy elements as uranium. In general, the extremely neutron-rich species of interest are produced together with an overwhelming amount of shorter-lived ones. Therefore, he is developing chemical and physical separation techniques with very high chemical selectivity. These studies are performed in international collaborations at high-flux reactors (Institut Laue-Langevin, France) or accelerator facilities as the CERN in Sw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Basel
The University of Basel (Latin: ''Universitas Basiliensis'', German: ''Universität Basel'') is a university in Basel, Switzerland. Founded on 4 April 1460, it is Switzerland's oldest university and among the world's oldest surviving universities. The university is traditionally counted among the leading institutions of higher learning in the country. The associated Basel University Library is the largest and among the most important libraries in Switzerland. The university hosts the faculties of theology, law, medicine, humanities and social sciences, science, psychology, and business and economics, as well as numerous cross-disciplinary subjects and institutes, such as the Biozentrum for biomedical research and the Institute for European Global Studies. In 2020, the university had 13,139 students and 378 professors. International students accounted for 27 percent of the student body. In its over 500-year history, the university has been home to Erasmus of Rotterdam, Parac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Mainz
The Johannes Gutenberg University Mainz (german: Johannes Gutenberg-Universität Mainz) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study. The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany. The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, the Goethe University Frankfurt and the Technische Universität Darmstadt together form the Rhine-Main-Universities (RMU). History The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova
A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the ''progenitor'', either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. Supernovae are more energetic than novae. In Latin language, Latin, ''nova'' means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word ''supernova'' was coined by Walter Baade and Fritz Zwicky in 1929. The last supernova to be directly observed in the Milky Way was Kepler's Supernova in 160 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided. All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208 Pb. On Earth, thorium and uranium are the only significantly radioactive elements that still occur naturally in large quantities as primordial elements. Thorium is estimated to be over three times as abundant as uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europium
Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanthanide, as it can be dented with a fingernail and easily cut with a knife. When oxidation is removed a shiny-white metal is visible. Europium was isolated in 1901 and is named after the continent of Europe. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3, but the oxidation state +2 is also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic as compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on Earth.Stwertka, Albert. ''A Guide to the Elements'', Oxford University Press, 1996, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Elements By Stability Of Isotopes
Atomic nuclei consist of protons and neutrons, which attract each other through the nuclear force, while protons repel each other via the electric force due to their positive charge. These two forces compete, leading to some combinations of neutrons and protons being more stable than others. Neutrons stabilize the nucleus, because they attract protons, which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus; if too many or too few neutrons are present with regard to the optimum ratio, the nucleus becomes unstable and subject to certain types of nuclear decay. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, or electron capture. Many rare types of decay, such as spontaneous fission or cluster decay, are known. (See Radioactive decay for details.) Of the first 82 elements in the periodic tab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
