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Philip Childs Keenan
Philip Childs Keenan (March 31, 1908 – April 20, 2000) was an American astronomer. Keenan was an American spectroscopist who collaborated with William Wilson Morgan and Edith Kellman (1911–2007) to develop the MKK stellar spectral classification system between 1939 and 1943. This two-dimensional classification system (temperature & luminosity) was further revised by Morgan and Keenan in 1973. The MK system remains the standard stellar spectral classification system used by astronomers today. During their long collaboration, Keenan tended to focus his research on stars cooler than the Sun, while Morgan emphasized the hotter stars. Keenan had a long and productive career, publishing his final scientific paper in 1999, seventy years after his first. Honors Named after him *Asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellevue, Pennsylvania
Bellevue is a borough in Allegheny County, Pennsylvania, United States, along the Ohio River, adjoining Pittsburgh. The population was 8,311 at the 2020 census. The borough was incorporated in 1867. There is a public park and library, the Andrew Bayne Memorial Library. Education Bellevue is served by the Northgate School District. History The land on which the borough currently sits was once part of the Depreciation Lands reserved for Revolutionary War veterans. The first landowners in the area were James Robinson and Hugh Henry Brackenridge, purchasing parcels in 1799 and 1792 respectively. At the time of its organization as a borough, Bellevue had exactly the minimum population for such a designation: 300 residents. Residents of the area tried unsuccessfully to obtain improvements from Ross Township, but officials were opposed to development along Venango Trail (today Route 19). In response, Bellevue was incorporated as a borough independent of Ross on September 7, 1867 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Maryland to its south, West Virginia to its southwest, Ohio to its west, Lake Erie and the Canadian province of Ontario to its northwest, New York to its north, and the Delaware River and New Jersey to its east. Pennsylvania is the fifth-most populous state in the nation with over 13 million residents as of 2020. It is the 33rd-largest state by area and ranks ninth among all states in population density. The southeastern Delaware Valley metropolitan area comprises and surrounds Philadelphia, the state's largest and nation's sixth most populous city. Another 2.37 million reside in Greater Pittsburgh in the southwest, centered around Pittsburgh, the state's second-largest and Western Pennsylvania's largest city. The state's su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbus, Ohio
Columbus () is the state capital and the most populous city in the U.S. state of Ohio. With a 2020 census population of 905,748, it is the 14th-most populous city in the U.S., the second-most populous city in the Midwest, after Chicago, and the third-most populous state capital. Columbus is the county seat of Franklin County; it also extends into Delaware and Fairfield counties. It is the core city of the Columbus metropolitan area, which encompasses 10 counties in central Ohio. The metropolitan area had a population of 2,138,926 in 2020, making it the largest entirely in Ohio and 32nd-largest in the U.S. Columbus originated as numerous Native American settlements on the banks of the Scioto River. Franklinton, now a city neighborhood, was the first European settlement, laid out in 1797. The city was founded in 1812 at the confluence of the Scioto and Olentangy rivers, and laid out to become the state capital. The city was named for Italian explorer Christopher Columbus. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ohio
Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The state's capital and largest city is Columbus, with the Columbus metro area, Greater Cincinnati, and Greater Cleveland being the largest metropolitan areas. Ohio is bordered by Lake Erie to the north, Pennsylvania to the east, West Virginia to the southeast, Kentucky to the southwest, Indiana to the west, and Michigan to the northwest. Ohio is historically known as the "Buckeye State" after its Ohio buckeye trees, and Ohioans are also known as "Buckeyes". Its state flag is the only non-rectangular flag of all the U.S. states. Ohio takes its name from the Ohio River, which in turn originated from the Seneca word ''ohiːyo'', meaning "good river", "great river", or "large creek". The state arose from the lands west of the Appalachian Mountai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, galaxies – in either observational astronomy, observational (by analyzing the data) or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, Sun, solar astronomy, the Star formation, origin or stellar evolution, evolution of stars, or the galaxy formation and evolution, formation of galaxies. A related but distinct subject is physical cosmology, which studies the Universe as a whole. Types Astronomers usually fall under either of two main types: observational astronomy, observational and theoretical astronomy, theoretical. Observational astronomers make direct observations of Astronomical object, celestial objects and analyze the data. In contrast, theoretical astronomers create and investigate C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yerkes Observatory
Yerkes Observatory ( ) is an astronomical observatory located in Williams Bay, Wisconsin, United States. The observatory was operated by the University of Chicago Department of Astronomy and Astrophysics from its founding in 1897 to 2018. Ownership was transferred to the non-profit Yerkes Future Foundation (YFF) in May 2020, which began restoration and renovation of the historic building and grounds. Re-opening for public tours and programming began May 27, 2022. The observatory, often called "the birthplace of modern astrophysics," was founded in 1892 by astronomer George Ellery Hale and financed by businessman Charles T. Yerkes. It represented a shift in the thinking about observatories, from their being mere housing for telescopes and observers, to the early-20th-century concept of observation equipment integrated with laboratory space for physics and chemistry analysis. The observatory's main dome houses a doublet lens refracting telescope, the largest refractor ever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perkins Observatory
Perkins Observatory is an astronomical observatory in Delaware, Ohio. It is owned and operated by Ohio Wesleyan University. In 1931 it had the third largest telescope in the World; the 69 inch aperture Perkins telescope came online at this observatory. The mirror was the largest cast in the United States up to that time, and it was made by the United States National Bureau of Standards. In the 1930s this observatory also started periodic document release called '' The Telescope,'' featuring results from the telescope but grew to include other astronomical information. The University partnered with Ohio State University in 1935, to help run the big telescope and the agreement lasted for almost seven decades. In the 1960s the telescope was moved to Arizona, USA for better viewing conditions, and fitted with new larger mirror. Nevertheless, the Observatory continued to be a hub of astronomical activity in the region and for the University. In the 21st century the Observatory suppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Wilson Morgan
William Wilson Morgan (January 3, 1906 – June 21, 1994) was an American astronomer and astrophysicist. The principal theme in Morgan's work was stellar and galaxy classification. He is also known for helping prove the existence of spiral arms in our galaxy. In addition to his scientific achievements he served as a professor and as astronomy director for University of Chicago, and was the managing editor for George Hale's Astrophysical Journal. Scientific achievements Along with Philip Keenan he developed the MK system for the classification of stars through their spectra. He also developed several galaxy morphological classification systems, including the first systems to use the physical, quantifiable properties of galaxies, as opposed to simple, qualitative, eyeball estimates favoured by Edwin Hubble. He invented the now widely used classification cD for massive galaxies in the centres of galaxy clusters. In 1970, along with astronomer Laura P. Bautz, they created the stil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edith Kellman
Edith Kellman (April 4, 1911, Walworth, Wisconsin – May 11, 2007, Walworth, Wisconsin) was a noted American astronomer who is known for her work on the Yerkes system of stellar classification, also called the MKK system. Early life and education Edith Kellman was born on April 4, 1911 in Walworth, Wisconsin to Ludvig and Ellen Levander Kellman. Kellman attended Wheaton College in Wheaton, Illinois. Career Kellman worked at the Yerkes Observatory as a photographic assistant, where she worked with William Morgan and Philip Keenan to develop the Yerkes system, an influential system of stellar classification. The MKK classification system was introduced in 1943 and was used by Morgan, Keenan, and Kellman to map the spiral structure of the Milky way using O and B star 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 gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grating into a spectrum exhibiting the Continuum (spectrum), 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 coo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
