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Charles Thomas Bolton
Charles Thomas Bolton (April 15, 1943 – ) was an American-Canadian astronomer who was one of the first in his field to present strong evidence of the existence of a stellar-mass black hole. Biography Bolton was born in Camp Forrest, a military base in Tullahoma, Tennessee. He received his bachelor's degree in 1966 from the University of Illinois, followed by a 1968 master's degree and a 1970 doctoral degrees from the University of Michigan. Bolton then worked as a postdoctoral researcher at the David Dunlap Observatory in Richmond Hill, Ontario, teaching there until 1972. He taught at Scarborough College from 1971 to 1972, and at Erindale College from 1972 to 1973. Thereafter, he was affiliated with the University of Toronto astronomy department, eventually becoming an emeritus professor. In 1970, Bolton developed the first computer models for stellar spectra that were precise enough to compare with data from real stars. In 1971, as a post-doctoral fellow and part-time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tullahoma, Tennessee
Tullahoma is a city in Coffee and Franklin counties in southern Middle Tennessee, United States. The population was 20,339 at the 2020 census. In 2019, the population was estimated to be 19,555. It is the principal city of the Tullahoma micropolitan area (a 2009 estimate placed it at 99,927), which consists of Coffee and Moore counties and is the second largest micropolitan area in Tennessee. The city is also partially in the Winchester Micropolitan area. History Tullahoma was founded in 1852 as a work camp along the new Nashville and Chattanooga Railroad. Its name is derived from the Choctaw language, and means "red rock". An alternative explanation (see Sam Davis Elliott's ''Soldier of Tennessee'' and sources cited therein) of the name is that Peter Decherd, who donated the land for the railroad right-of-way (and was therefore given the right to name two stations along the line), named one station Decherd, after himself, and the other as Tulkahoma (later changed to Tulla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul Murdin
Paul Geoffrey Murdin (born 5 January 1942) is a British astronomer. He identified the first clear candidate for a black hole, Cygnus X-1, with his colleague Louise Webster. He studied Mathematics and Physics at the universities of Oxford and Rochester. In 1962, he took an eight-week summer residential course supporting researchers at the Royal Greenwich Observatory in Herstmonceux and at the end was offered a post by the Astronomer Royal, Richard Woolley. He left to study a PhD at Rochester and returned to the RGO in 1970 as a research fellow. During his three-year contract there, he wondered what he could contribute to find out about the provenance of powerful cosmic x-ray sources that had recently been detected, particularly Cygnus X-1. After he had made unsuccessful searches for light variations and unusual spectra among the hundreds of stars within the area of positional uncertainty of the X-ray source, a radio star was found that was coincident with a star HDE226868 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2021 Deaths
This is a list of lists of deaths of notable people, organized by year. New deaths articles are added to their respective month (e.g., Deaths in ) and then linked below. 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 Earlier years ''Deaths in years earlier than this can usually be found in the main articles of the years.'' See also * Lists of deaths by day * Deaths by year (category) {{DEFAULTSORT:deaths by year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1943 Births
Events Below, the events of World War II have the "WWII" prefix. January * January 1 – WWII: The Soviet Union announces that 22 German divisions have been encircled at Stalingrad, with 175,000 killed and 137,650 captured. * January 4 – WWII: Greek-Polish athlete and saboteur Jerzy Iwanow-Szajnowicz is executed by the Germans at Kaisariani. * January 10 – WWII: Guadalcanal campaign, Guadalcanal Campaign: American forces of the 2nd Marine Division and the 25th Infantry Division (United States), 25th Infantry Division begin their assaults on the Battle of Mount Austen, the Galloping Horse, and the Sea Horse#Galloping Horse, Galloping Horse and Sea Horse on Guadalcanal. Meanwhile, the Japanese Seventeenth Army (Japan), 17th Army makes plans to abandon the island and after fierce resistance withdraws to the west coast of Guadalcanal. * January 11 ** The United States and United Kingdom revise previously unequal treaty relationships with the Republic of China (1912–194 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulletin Of The American Astronomical Society
''Bulletin of the American Astronomical Society'' (''BAAS''; ''Bull. Am. Astron. Soc.'') is the journal of record for the American Astronomical Society established in 1969. It publishes meetings of the society, obituaries of its members, and scholarly articles. Four issues are published per year that are collected into a single volume. Articles are indexed, and often archived, from the Astrophysics Data System The SAO/NASA Astrophysics Data System (ADS) is a digital library portal for researchers on astronomy and physics, operated for NASA by the Smithsonian Astrophysical Observatory. ADS maintains three bibliographic collections containing over 15 ..., using the journal code BAA. External links * Academic journals established in 1969 Astronomy journals English-language journals Quarterly journals American Astronomical Society academic journals {{astronomy-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Pollution
Light pollution is the presence of any unwanted, inappropriate, or excessive artificial Visible spectrum, lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting sources, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution. Although this type of pollution can exist throughout the day, its effects are magnified during the night with the contrast of the sky's darkness. It has been estimated that 83% of the world's people live under light-polluted skies and that 23% of the world's land area is affected by skyglow. The area affected by artificial illumination continues to increase. A major side effect of urbanization, light pollution is blamed for compromising health, disrupting ecosystems, and spoiling aesthetic environments. Studies show that ur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, 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 to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. The last supernova directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye. The supernova remnant, remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstellar Medium
The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic medium. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. Although the density of atoms in the ISM is usually far below that in the best laboratory vacuums, the mean free path between collisions is short compared to typical interstellar lengths, so on these scales the ISM behaves as a gas (more precisely, as a Plasma (physics), plasma: it is everywhere at least slightly ionized), responding to pressure forces, and not as a collection of non-interacting particles. The interstellar medium is composed of multiple phases distinguished by whether matter is ionic, atomic, or molecular, and the temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity
Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical quantity, quantity, meaning that both magnitude and direction are needed to define it. The Scalar (physics), scalar absolute value (Magnitude (mathematics), magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the International System of Units, SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Definition Average velocity The average velocity of an object over a period of time is its Displacement (geometry), change in position, \Delta s, divided by the duration of the period, \Delt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Kinematics
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as the internal kinematics of more distant galaxies. Measurement of the kinematics of stars in different subcomponents of the Milky Way including the thin disk, the thick disk, the bulge, and the stellar halo provides important information about the formation and evolutionary history of our Galaxy. Kinematic measurements can also identify exotic phenomena such as hypervelocity stars escaping from the Milky Way, which are interpreted as the result of gravitational encounters of binary stars with the supermassive black hole at the Galactic Center. Stellar kinematics is related to but distinct from the subject of stellar dynamics, which involves the theoretical study or modeling of the motions of stars under the influence of gravity. Stel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye. The Milky Way is a barred spiral galaxy with a Galaxy#Isophotal diameter, D25 isophotal diameter estimated at , but only about 1,000 light-years thick at the spiral arms (more at the bulge). Recent simulations suggest that a dark matter area, also containing some visible stars, may extend up to a diameter of almost 2 million light-years (613 kpc). The Milky Way has several List of Milky Way's satellite galaxies, satellite galaxies and is part of the Local Group of galaxies, forming part of the Virgo Supercluster which is itself a component of the Laniakea Supercluster. It is estimated to contain 100–400 billion stars and at least that number of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cygnus X-1
Cygnus X-1 (abbreviated Cyg X-1) is a galactic X-ray source in the constellation Cygnus and was the first such source widely accepted to be a black hole. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources detectable from Earth, producing a peak X-ray flux density of (). It remains among the most studied astronomical objects in its class. The compact object is now estimated to have a mass about 21.2 times the mass of the Sun and has been shown to be too small to be any known kind of normal star or other likely object besides a black hole. If so, the radius of its event horizon has "as upper bound to the linear dimension of the source region" of occasional X-ray bursts lasting only for about 1 ms. Cygnus X-1 belongs to a high-mass X-ray binary system, located about 7,000 light-years away, that includes a blue supergiant variable star designated HDE 226868, which it orbits at about 0.2 AU, or 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
