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Joel Stebbins
Joel Stebbins (July 30, 1878 – March 16, 1966) was an American astronomer who pioneered photoelectric photometry in astronomy. He was director of the University of Illinois Observatory from 1903 to 1922 where he performed innovative work with the selenium cell. In 1922 he became director of the Washburn Observatory at the University of Wisconsin–Madison where he remained until 1948. After 1948, Stebbins continued his research at Lick Observatory until his final retirement in 1958. Stebbins brought photoelectric photometry from its infancy in the early 1900s to a mature technique by the 1950s, when it succeeded photography as the primary method of photometry. He used the new technique to investigate eclipsing binaries, the reddening of starlight by interstellar dust, colors of galaxies, and variable stars. Biography Joel Stebbins was born in Omaha, Nebraska, on July 30, 1878, the son of Charles Stebbins, an office worker at the Union Pacific Railroad and his wife Sara Ann né ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omaha, Nebraska
Omaha ( ) is the largest city in the U.S. state of Nebraska and the county seat of Douglas County. Omaha is in the Midwestern United States on the Missouri River, about north of the mouth of the Platte River. The nation's 39th-largest city, Omaha's 2020 census population was 486,051. Omaha is the anchor of the eight-county, bi-state Omaha-Council Bluffs metropolitan area. The Omaha Metropolitan Area is the 58th-largest in the United States, with a population of 967,604. The Omaha-Council Bluffs-Fremont, NE-IA Combined Statistical Area (CSA) totaled 1,004,771, according to 2020 estimates. Approximately 1.5 million people reside within the Greater Omaha area, within a radius of Downtown Omaha. It is ranked as a global city by the Globalization and World Cities Research Network, which in 2020 gave it "sufficiency" status. Omaha's pioneer period began in 1854, when the city was founded by speculators from neighboring Council Bluffs, Iowa. The city was founded along th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Stars
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, photodiode, or photomultiplier. Photometers measure: *Illuminance *Irradiance *Light absorption * Scattering of light *Reflection of light *Fluorescence *Phosphorescence *Luminescence History Before electronic light sensitive elements were developed, photometry was done by estimation by the eye. The relative luminous flux of a source was compared with a standard source. The photometer is placed such that the illuminance from the source being investigated is equal to the standard source, as the human eye can judge equal illuminance. The relative luminous fluxes can then be calculated as the illuminance decreases proportionally to the inverse square of distance. A standard example of such a photometer consists of a piece of paper with an o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophysical Journal
''The Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and became an electronic-only journal in 2015. Since 1953 ''The Astrophysical Journal Supplement Series'' (''ApJS'') has been published in conjunction with ''The Astrophysical Journal'', with generally longer articles to supplement the material in the journal. It publishes six volumes per year, with two 280-page issues per volume. ''The Astrophysical Journal Letters'' (''ApJL''), established in 1967 by Subrahmanyan Chandrasekhar as Part 2 of ''The Astrophysical Journal'', is now a separate journal focusing on the rapid publication of high-impact astronomical research. The three journals were published by the University of Chicago Press for the American Astronomical Society unt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omicron Ceti
Mira (), designation Omicron Ceti (ο Ceti, abbreviated Omicron Cet, ο Cet), is a red-giant star estimated to be 200–400 light-years from the Sun in the constellation Cetus. ο Ceti is a Binary star, binary stellar system, consisting of a variable red giant (Mira A) along with a white dwarf companion (Mira B). Mira A is a pulsating variable star and was the first non-supernova variable star discovered, with the possible exception of Algol. It is the prototype of the Mira variables. Nomenclature ο Ceti (Romanization of Greek, Latinised to ''Omicron Ceti'') is the star's Bayer designation. It was named Mira (Latin for 'wonderful' or 'astonishing') by Johannes Hevelius in his ''Historiola Mirae Stellae'' (1662). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absorption Spectrum
Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum. Absorption spectroscopy is employed as an analytical chemistry tool to determine the presence of a particular substance in a sample and, in many cases, to quantify the amount of the substance present. Infrared and ultraviolet–visible spectroscopy are particularly common in analytical applications. Absorption spectroscopy is also employed in studies of molecular and atomic physics, astronomical spectroscopy and remote sensing. There is a wide range of experimental approaches for measuring absorption spectra. The most common arrangement is to dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doctor Of Philosophy
A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common Academic degree, degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is an earned research degree, those studying for a PhD are required to produce original research that expands the boundaries of knowledge, normally in the form of a Thesis, dissertation, and defend their work before a panel of other experts in the field. The completion of a PhD is often a requirement for employment as a university professor, researcher, or scientist in many fields. Individuals who have earned a Doctor of Philosophy degree may, in many jurisdictions, use the title ''Doctor (title), Doctor'' (often abbreviated "Dr" or "Dr.") with their name, although the proper etiquette associated with this usage may also be subject to the professional ethics of their own scholarly field, culture, or society. Those who teach at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of California
The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, Santa Barbara, and Santa Cruz, along with numerous research centers and academic abroad centers. The system is the state's land-grant university. Major publications generally rank most UC campuses as being among the best universities in the world. Six of the campuses, Berkeley, Davis, Irvine, Los Angeles, Santa Barbara, and San Diego are considered Public Ivies, making California the state with the most universities in the nation to hold the title. UC campuses have large numbers of distinguished faculty in almost every academic discipline, with UC faculty and researchers having won 71 Nobel Prizes as of 2021. The University of California currently has 10 campuses, a combined student body of 285,862 students, 24,400 faculty members, 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nova Persei
GK Persei (also Nova Persei 1901) was a bright nova first observed on Earth in 1901. It was discovered by Thomas David Anderson, an Edinburgh clergyman, at 02:40 UT on 22 February 1901 when it was at magnitude 2.7. It reached a maximum magnitude of 0.2, the brightest nova of modern times until Nova Aquilae 1918. After fading into obscurity at about magnitude 12 to 13 during the early 20th century, GK Persei began displaying infrequent outbursts of 2 to 3 magnitudes (about 7 to 15 times quiescent brightness). Since about 1980, these outbursts have become quite regular, typically lasting about two months and occurring about every three years. Thus, GK Persei seems to have changed from a classical nova like Nova Aquilae 1918 to something resembling a typical dwarf nova-type cataclysmic variable star. Surrounding GK Persei is the Firework nebula, a nova remnant first detected in 1902 consisting of an expanding cloud of gas and dust bubbles moving up to 1200 km/s. GK Per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequency interval or band. Light curves can be periodic, as in the case of eclipsing binaries, Cepheid variables, other periodic variables, and transiting extrasolar planets, or aperiodic, like the light curve of a nova, a cataclysmic variable star, a supernova or a microlensing event or binary as observed during occultation events. The study of the light curve, together with other observations, can yield considerable information about the physical process that produces it or constrain the physical theories about it. Variable stars Graphs of the apparent magnitude of a variable star over time are commonly used to visualise and analyse their behaviour. Although the categorisation of variable star types is increasingly done from their s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Comstock (astronomer)
George Cary Comstock (February 12, 1855 – May 11, 1934) was an American astronomer and educator. Biography George Comstock was born in Madison, Wisconsin on February 12, 1855, the eldest child of Charles Henry Comstock and Mercy Bronson. In 1877 he was awarded a Ph.B. from the University of Michigan, after studying mathematics and astronomy. For a couple of years he worked for the U.S. Lake Survey and then a Mississippi River improvement project, before joining Washburn Observatory as the assistant director in 1879. As career insurance, during his free moments he studied law and was admitted to the Wisconsin bar in 1883 after graduating from Wisconsin law school. However, he would never practice the legal profession. He was appointed professor at Ohio State University in 1887, where he taught mathematics and astronomy, and he took over directorship of the Washburn Observatory. On June 12, 1894, he was married to Esther Cecile Everett, and the couple had a daughter, Mary Cecelia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bachelor Of Science
A Bachelor of Science (BS, BSc, SB, or ScB; from the Latin ') is a bachelor's degree awarded for programs that generally last three to five years. The first university to admit a student to the degree of Bachelor of Science was the University of London in 1860. In the United States, the Lawrence Scientific School first conferred the degree in 1851, followed by the University of Michigan in 1855. Nathaniel Southgate Shaler, who was Harvard's Dean of Sciences, wrote in a private letter that "the degree of Bachelor of Science came to be introduced into our system through the influence of Louis Agassiz, who had much to do in shaping the plans of this School." Whether Bachelor of Science or Bachelor of Arts degrees are awarded in particular subjects varies between universities. For example, an economics student may graduate as a Bachelor of Arts in one university but as a Bachelor of Science in another, and occasionally, both options are offered. Some universities follow the Oxford a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
