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SN 1972e
SN1972E was a supernova in the galaxy NGC 5253 that was discovered 13 May 1972 with an apparent B magnitude of about 8.5, shortly after it had reached its maximum brightness. In terms of apparent brightness, it was the second-brightest supernova of any kind (fainter only than SN 1987A) of the 20th century. It was observed for nearly 700 days, and it became the prototype object for the development of theoretical understanding of Type Ia supernovae. Background The supernova was discovered by Charles Kowal, about 56 arc seconds west and 85 arc seconds south of the center of NGC 5253. The position in the periphery of the galaxy aided observation, minimizing interference by background objects. Well-positioned for Southern Hemisphere observers, it was quite observable from Northern Hemisphere observatories as well. Attempts made to observe it in X-rays with Uhuru and OSO 7 and to detect gamma rays from it via Cherenkov radiation showers gave at best equivocal results. Photomet ... [...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] |
Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Supernovae
This is a list of supernovae that are of historical significance. These include supernovae that were observed prior to the availability of photography, and individual events that have been the subject of a scientific paper that contributed to supernova theory. An alternative, complete and updated list can be found in thOpen Supernova Catalog List ''In most entries, the year when the supernova was seen is part of the designation (1st column).'' See also * List of most distant supernovae * List of supernova candidates * List of supernova remnants * Lists of astronomical objects References Further reading * External linksList of all known supernovaeaThe Open Supernova CatalogIAU Supernovaeon thTransient Name Server (TNS) at IAU |
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] |
Chandrasekhar Limit
The Chandrasekhar limit () is the maximum mass of a stable white dwarf star. The currently accepted value of the Chandrasekhar limit is about (). White dwarfs resist gravitational collapse primarily through electron degeneracy pressure, compared to main sequence stars, which resist collapse through thermal pressure. The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star's core is insufficient to balance the star's own gravitational self-attraction. Consequently, a white dwarf with a mass greater than the limit is subject to further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or black hole. Those with masses up to the limit remain stable as white dwarfs.Sean Carroll, Ph.D., Caltech, 2007, The Teaching Company, ''Dark Matter, Dark Energy: The Dark Side of the Universe'', Guidebook Part 2 page 44, Accessed Oct. 7, 2013, "...Chandrasekhar limit: The maximum mass of a white dwarf star, about 1.4 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Dwarf
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes from the emission of residual thermal energy; no fusion takes place in a white dwarf. The nearest known white dwarf is at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name ''white dwarf'' was coined by Willem Luyten in 1922. White dwarfs are thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star or black hole. This includes over 97% of the other stars in the Milky Way. After the hydrogen- fusing period of a main-sequence star of low or medium mass ends, such a star will expand to a red giant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Nickel
Naturally occurring nickel (28Ni) is composed of five stable isotopes; , , , and , with being the most abundant (68.077% natural abundance). 26 radioisotopes have been characterised with the most stable being with a half-life of 76,000 years, with a half-life of 100.1 years, and with a half-life of 6.077 days. All of the remaining radioactive isotopes have half-lives that are less than 60 hours and the majority of these have half-lives that are less than 30 seconds. This element also has 8 meta states. List of isotopes , - , , style="text-align:right" , 28 , style="text-align:right" , 20 , 48.01975(54)# , 10# ms 500 ns, , , 0+ , , , - , , style="text-align:right" , 28 , style="text-align:right" , 21 , 49.00966(43)# , 13(4) ms 2(+5−3) ms, , , 7/2−# , , , - , , style="text-align:right" , 28 , style="text-align:right" , 22 , 49.99593(28)# , 9.1(18) ms , β+ , 50Co , 0+ , , , - , , style="text-align:right" , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of the Sun. This equates to about two nonillion (short scale), two quintillion (long scale) kilograms or 2000 quettagrams: The solar mass is about times the mass of Earth (), or times the mass of Jupiter (). History of measurement The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance. The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of the Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of (9 arcseconds, compared to the present value of ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Cobalt
Naturally occurring cobalt (Co) consists of a single stable isotope, Co. Twenty-eight radioisotopes have been characterized; the most stable are Cobalt-60, Co with a half-life of 5.2714 years, Co (271.8 days), Co (77.27 days), and Co (70.86 days). All other isotopes have half-lives less than 18 hours and most of these have half-lives less than 1 second. This element also has 11 meta states, all of which have half-lives less than 15 minutes. The isotopes of cobalt range in atomic weight from Co to Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, Co, is electron capture and the main mode of decay for those of greater than 59 atomic mass units is beta decay. The main decay products before Co are iron isotopes and the main products after are nickel isotopes. Radioactive isotopes can be produced by various nuclear reactions. For example, Co is produced by cyclotron irradiation of iron. The main reaction is the (d,n) reaction Fe + H → n + Co. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, ''half-life period'', dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to ''half-life'' in the early 1950s. Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnitude (astronomy)
In astronomy, magnitude is a unitless measure of the brightness Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ... of an astronomical object, object in a defined passband, often in the visible spectrum, visible or infrared spectrum, but sometimes across all wavelengths. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. The scale is Logarithmic scale, logarithmic and defined such that a magnitude 1 star is exactly 100 times brighter than a magnitude 6 star. Thus each step of one magnitude is \sqrt[5] \approx 2.512 times brighter than the magnitude 1 higher. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. Astronomers use two different defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction (astronomy)
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler. However, its effects had been noted in 1847 by Friedrich Georg Wilhelm von Struve, and its effect on the colors of stars had been observed by a number of individuals who did not connect it with the general presence of galactic dust. For stars that lie near the plane of the Milky Way and are within a few thousand parsecs of the Earth, extinction in the visual band of frequencies (photometric system) is roughly 1.8 magnitudes per kiloparsec. For Earth-bound observers, extinction arises both from the interstellar medium (ISM) and the Earth's atmosphere; it may also arise from circumstellar dust around an observed object. Strong extinction in earth's atmosphere of some wavelength regions (such as X-ray, ultraviolet, and infrared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
