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Iron Star
In astronomy, an iron star is a hypothetical type of compact star. Unrelatedly, the term "iron star" is also used for blue supergiants which have a forest of forbidden FeII lines in their spectra. They are potentially quiescent hot luminous blue variables. Eta Carinae has been described as a prototypical example. Formation An iron star is a hypothetical type of compact star that could occur in the universe in the extremely far future, after perhaps 101500 years. The premise behind the formation of iron stars states that cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into iron-56 nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting stellar-mass objects to cold spheres of iron. The formation of these stars is only a possibility if protons do not decay. Though the surface of a neutron star may be iron according to some predictions, it is distinct from an iron star. By the end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest include planets, natural satellite, moons, stars, nebulae, galaxy, galaxies, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond atmosphere of Earth, Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonian astronomy, Babylonians, Greek astronomy, Greeks, Indian astronomy, Indians, Egyptian astronomy, Egyptians, Chinese astronomy, Chinese, Maya civilization, Maya, and many anc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Future Of An Expanding Universe
Observations suggest that the expansion of the universe will continue forever. The prevailing theory is that the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario once popularly called "Heat Death" is now known as the "Big Chill" or "Big Freeze". If dark energy—represented by the cosmological constant, a ''constant'' energy density filling space homogeneously, or scalar fields, such as quintessence or moduli, ''dynamic'' quantities whose energy density can vary in time and space—accelerates the expansion of the universe, then the space between clusters of galaxies will grow at an increasing rate. Redshift will stretch ancient, incoming photons (even gamma rays) to undetectably long wavelengths and low energies. Stars are expected to form normally for 1012 to 1014 (1–100 trillion) years, but eventually the supply of gas needed for star formation will be exhausted. As existing stars run out of fuel and cease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothetical Stars
A hypothetical star is a star, or type of star, that is speculated to exist but has yet to be definitively observed. Hypothetical types of stars have been conjectured to exist, have existed or will exist in the future universe. Types Scientifically speculated hypothetical types include: Specific stars Specific hypothetical stars include: See also *Hypothetical astronomical object Various unknown astronomical objects have been hypothesized throughout recorded history. For example, in the 5th century BCE, the philosopher Philolaus defined a hypothetical astronomical object which he called the "Central Fire", around which ... References Further reading *Schunck, F.E. and E.W. Mielke: "General relativistic boson stars", Class. Quantum. Grav. Vol. 20, R301 - R356 (2003) {{star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Types
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Death Of The Universe
The heat death of the universe (also known as the Big Chill or Big Freeze) is a hypothesis on the ultimate fate of the universe, which suggests the universe will evolve to a state of no thermodynamic free energy, and will therefore be unable to sustain processes that increase entropy. Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium. The Heat Death theory has become the leading theory in the modern age with the fewest unpredictable factors. If the topology of the universe is open or flat, or if dark energy is a positive cosmological constant (both of which are consistent with current data), the universe will continue expanding forever, and a heat death is expected to occur, with the universe cooling to approach equilibrium at a very low temperature after a very long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothetical Star
A hypothetical star is a star, or type of star, that is speculated to exist but has yet to be definitively observed. Hypothetical types of stars have been conjectured to exist, have existed or will exist in the future universe. Types Scientifically speculated hypothetical types include: Specific stars Specific hypothetical stars include: See also *Hypothetical astronomical object Various unknown astronomical objects have been hypothesized throughout recorded history. For example, in the 5th century BCE, the philosopher Philolaus defined a hypothetical astronomical object which he called the "Central Fire", around which ... References Further reading *Schunck, F.E. and E.W. Mielke: "General relativistic boson stars", Class. Quantum. Grav. Vol. 20, R301 - R356 (2003) {{star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steady-state Model
In cosmology, the steady-state model, or steady state theory is an alternative to the Big Bang theory of evolution of the universe. In the steady-state model, the density of matter in the expanding universe remains unchanged due to a continuous creation of matter, thus adhering to the perfect cosmological principle, a principle that asserts that the observable universe is practically the same at any time and any place. While from the 1940s to the 1960s the astrophysical community was equally divided between supporters of the Big Bang theory and supporters of the steady-state theory, it is now rejected by the vast majority of cosmologists, astrophysicists and astronomers, as the observational evidence points to a hot Big Bang cosmology with a finite age of the universe, which the steady-state model does not predict. History In the 13th century, Siger of Brabant authored the thesis ''The Eternity of the World'', which argued that there was no first man, and no first specimen o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ivan Yefremov
Ivan Antonovich (real patronymic Antipovich) Yefremov ( ru , Ива́н Анто́нович (Анти́пович) Ефре́мов; April 23, 1908 – October 5, 1972; last name sometimes transliterated as Efremov) was a Soviet paleontologist, science-fiction author and social thinker. He founded taphonomy, the study of fossilization patterns. Biography He was born in the village of Vyritsa in Saint Petersburg Governorate on April 23, 1908. His parents divorced during the Russian Revolution. His mother married a Red Army commander and left the children in Kherson to be cared for by an aunt who soon died of typhus. Yefremov survived on his own for some time, after which he joined a Red Army unit as a "son of the regiment" and went to Perekop with it. In 1921, he was discharged and went to Petrograd (today's Saint Petersburg) to study. He completed his education there while combining his studies with a variety of odd jobs. He later commented that "the Revolution was als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andromeda (novel)
''Andromeda: A Space-Age Tale'' (russian: "Туманность Андромеды", ''Tumannost' Andromedy'' – ''Andromeda Nebula'') is a science fiction novel by the Soviet writer and paleontologist Ivan Yefremov,Sergey Klimanov's Home PageIvan Yefremov's WorksRevised 2004-08-10. Accessed 2006-09-08. written in 1955–1956 and published in 1957. It was translated into English as ''Andromeda: A Space-Age Tale'' by George Hanna. The novel predicted some future inventions ( borazon, space probe, powered exoskeleton and ion thruster). It was made into a film in 1967, ''The Andromeda Nebula''. Yefremov's 1958 short story " The Heart of the Serpent" and 1968 novel ''The Bull's Hour'', which is set in the same universe taking place some 200 years later, are considered as its sequels. Plot summary The book portrays Yefremov's conception of a classic communist utopia set in a distant future. Throughout the novel, the author's attention is focused on the social and cultural aspe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Andromeda Nebula
''The Andromeda Nebula'' (russian: Туманность Андромеды) is a 1967 Soviet science fiction film starring Sergei Stolyarov and directed by Yevgeni Sherstobitov at the Dovzhenko Film Studios. The film was originally intended to be the first episode of a series of films, alternatively titled as ''The Andromeda Nebula: Episode I. Prisoners of the Iron Star'', but the remaining parts were never made due to Stolyarov's death. Plot The film is based upon the 1957 novel '' Andromeda Nebula'' by Ivan Yefremov. It follows the story of a group of humans on the spaceship ''Tantra'' who are tasked with investigating the home planet of an alien race. They discover that artificial radioactivity has killed almost all life on that planet. During the voyage home the ship is trapped by the gravitational force of an iron star and lands on a planet orbiting the star. Surrounded by predators who destroy human nervous system through space suits, the crew has to fight to see Earth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reviews Of Modern Physics
''Reviews of Modern Physics'' (abbreviated RMP) is a quarterly peer-reviewed scientific journal published by the American Physical Society. It was established in 1929 and the current editor-in-chief is Michael Thoennessen. The journal publishes review articles, usually by established researchers, on all aspects of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ... and related fields. The reviews are usually accessible to non-specialists and serve as introductory material to graduate students, which survey recent work, discuss key problems to be solved and provide perspectives toward the end. References External links * Publications established in 1929 Physics review journals Quarterly journals English-language journals American Physical Society academic journ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Decay
Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium-4 atom, which consists of two protons and two neutrons. It has a charge of and a mass of . For example, uranium-238 decays to form thorium-234. While alpha particles have a charge , this is not usually shown because a nuclear equation describes a nuclear reaction without considering the electrons – a convention that does not imply that the nuclei necessarily occur in neutral atoms. Alpha decay typically occurs in the heaviest nuclides. Theoretically, it can occur only in nuclei somewhat heavier than nickel (element 28), where the overall binding energy per nucleon is no longer a maximum and the nuclides are therefore unstable toward spontaneou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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