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Willem J. Luyten
Willem Jacob Luyten (March 7, 1899 – November 21, 1994) was a Dutch-American astronomer. "Willem Jacob Luyten", ''Marquis Who's Who'', 2006. Life Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His mother was Cornelia M. Francken and his father Jacob Luyten, a teacher of French. At the age of 11 he observed Halley's Comet, which started his fascination with astronomy. He also had a knack for languages, and eventually could speak nine. In 1912 his family moved back to the Netherlands where he studied astronomy at the University of Amsterdam, receiving his BA in 1918. He was the first student to earn his PhD (at the age of 22) with Ejnar Hertzsprung at Leiden University. In 1921 he left for the United States where he first worked at the Lick Observatory. From 1923 to 1930 Luyten worked at the Harvard College Observatory eventually working at the observatory's Bloemfontein station. He spent the years 1928–1930 in Bloemfontein, South ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semarang
Semarang ( jv, ꦏꦸꦛꦯꦼꦩꦫꦁ , Pegon: سماراڠ) is the capital and largest city of Central Java province in Indonesia. It was a major port during the Dutch colonial era, and is still an important regional center and port today. The city has been named as the cleanest tourist destination in Southeast Asia by the ASEAN Clean Tourist City Standard (ACTCS) for 2020–2022. It has an area of and is located at . The population of the city was 1,555,984 at the 2010 censusBiro Pusat Statistik, Jakarta, 2011. and 1,653,524 at the 2020 census,Badan Pusat Statistik, Jakarta, 2021. making it Indonesia's ninth most populous city after Jakarta, Surabaya, Bekasi, Bandung, Medan, Depok, Tangerang and Palembang. The built-up urban area had 3,183,516 inhabitants at the 2010 census spread over two cities and 26 districts. The Semarang metropolitan area (a.k.a. ''Kedungsepur'') has a population of over 6 million in 2020 (''see Greater Semarang section''). The population of the cit ... [...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 an online database of over 16 million astronomy and physics papers from both peer reviewed and non-peer reviewed sources. Abstracts are available free online for almost all articles, and full scanned a ..., using the journal code BAAS. External links * Publications 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] |
1964 Luyten
Events January * January 1 – The Federation of Rhodesia and Nyasaland is dissolved. * January 5 - In the first meeting between leaders of the Roman Catholic and Orthodox churches since the fifteenth century, Pope Paul VI and Patriarch Athenagoras I of Constantinople meet in Jerusalem. * January 6 – A British firm, the Leyland Motor Corp., announces the sale of 450 buses to the Cuban government, challenging the United States blockade of Cuba. * January 9 – ''Martyrs' Day'': Armed clashes between United States troops and Panamanian civilians in the Panama Canal Zone precipitate a major international crisis, resulting in the deaths of 21 Panamanians and 4 U.S. soldiers. * January 11 – United States Surgeon General Luther Terry reports that smoking may be hazardous to one's health (the first such statement from the U.S. government). * January 12 ** Zanzibar Revolution: The predominantly Arab government of Zanzibar is overthrown by African nationalist rebels; a United ... [...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] |
LTT 1445
LTT 1445 is a triple M-dwarf system about 22 light-years distant in the constellation Eridanus. The primary LTT 1445 A hosts two exoplanets- one discovered in 2019 that transits the star every 5.36 days, and another found in 2021 that transits the star every 3.12 days, close to a 12:7 resonance. As of August 2019 it is the second closest transiting exoplanet system discovered, with the closest being HD 219134 bc. Stellar system All three stars in the system are M-dwarfs, with masses between 0.16 and 0.26 . LTT 1445 A and LTT 1445 BC are separated by about 34 astronomical units and orbit each other with a period of about 250 years. The BC pair orbit each other about every 36 years in an eccentric orbit (e= ~0.5). The alignment of the three stars and the edge-on orbit of the BC pair suggests co-planarity of the system. The existence of a transiting planet LTT 1445Ab suggests that the entire system is co-planar, with orbits in one plane. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UV Ceti
Luyten 726-8, also known as Gliese 65, is a binary star system that is one of Earth's nearest neighbors, at about 8.7 light years from Earth in the constellation Cetus. The two component stars are both flare stars with the variable star designations BL Ceti and UV Ceti. Star system The star system was discovered in 1948 by Willem Jacob Luyten in the course of compiling a catalog of stars of high proper motion; he noted its exceptionally high proper motion of 3.37 arc seconds annually and cataloged it as Luyten . The two stars are of nearly equal brightness, with visual magnitudes of 12.7 and 13.2 as seen from Earth. They orbit one another every 26.5 years. The distance between the two stars varies from . The Luyten 726-8 system is approximately from Earth's Solar System, in the constellation Cetus, and is thus the seventh-closest star system to Earth. Its own nearest neighbor is Tau Ceti, away from it. If R_v=+29 km/s then approximately 28,700 years ago Luyten 7 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare Star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X-rays to radio waves. The first known flare stars ( V1396 Cygni and AT Microscopii) were discovered in 1924. However, the best-known flare star is UV Ceti, first observed to flare in 1948. Today similar flare stars are classified as UV Ceti type variable stars (using the abbreviation UV) in variable star catalogs such as the General Catalogue of Variable Stars. Most flare stars are dim red dwarfs, although recent research indicates that less massive brown dwarfs might also be capable of flaring. The more massive RS Canum Venaticorum variables (RS CVn) are also known to flare, but it is understood that these flares are induced by a companion star in a binary system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luyten 726-8
Luyten 726-8, also known as Gliese 65, is a binary star system that is one of Earth's nearest neighbors, at about 8.7 light years from Earth in the constellation Cetus. The two component stars are both flare stars with the variable star designations BL Ceti and UV Ceti. Star system The star system was discovered in 1948 by Willem Jacob Luyten in the course of compiling a catalog of stars of high proper motion; he noted its exceptionally high proper motion of 3.37 arc seconds annually and cataloged it as Luyten . The two stars are of nearly equal brightness, with visual magnitudes of 12.7 and 13.2 as seen from Earth. They orbit one another every 26.5 years. The distance between the two stars varies from . The Luyten 726-8 system is approximately from Earth's Solar System, in the constellation Cetus, and is thus the seventh-closest star system to Earth. Its own nearest neighbor is Tau Ceti, away from it. If R_v=+29 km/s then approximately 28,700 years ago Luyten 726-8 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luyten's Star
Luyten's Star (GJ 273) is a red dwarf in the constellation Canis Minor located at a distance of approximately from the Sun. It has a visual magnitude of 9.9, making it too faint to be viewed with the unaided eye. It is named after Willem Jacob Luyten, who, in collaboration with Edwin G. Ebbighausen, first determined its high proper motion in 1935. The star has two confirmed planets and two candidate planets, of which Luyten b is in the circumstellar habitable zone. Properties This star is approximately a quarter the mass of the Sun and has 35% of the Sun's radius. Luyten's Star is at the maximum mass at which a red dwarf can be fully convective, which means that most if not all of the star forms an extended convection zone. It has a stellar classification of M3.5V, with the V luminosity class indicating this is a main-sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. The projected rotation rate of this star is too ... [...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] |
Proper Motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars. The components for proper motion in the equatorial coordinate system (of a given epoch, often J2000.0) are given in the direction of right ascension (''μ''α) and of declination (''μ''δ). Their combined value is computed as the ''total proper motion'' (''μ''). It has dimensions of angle per time, typically arcseconds per year or milliarcseconds per year. Knowledge of the proper motion, distance, and radial velocity allows calculations of an object's motion from our star system's frame of reference and its motion from the galactic frame of reference – that is motion in respect to the Sun, and by coordinate transformation, that in respect to the Milky Way. Introduction Over the course of centuries, stars appear t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bloemfontein
Bloemfontein, ( ; , "fountain of flowers") also known as Bloem, is one of South Africa's three capital cities and the capital of the Free State (province), Free State province. It serves as the country's judicial capital, along with legislative capital Cape Town and Administration (government), administrative capital Pretoria. Bloemfontein is the seventh-largest city in South Africa. Situated at an elevation of above sea level, the city is home to approximately 520,000 residents and forms part of the Mangaung Metropolitan Municipality which has a population of 747,431. It was one of the host cities for the 2010 FIFA World Cup. The city of Bloemfontein hosts the Supreme Court of Appeal (South Africa), Supreme Court of Appeal of South Africa, the Franklin Game Reserve, :af:Naval Hill, Naval Hill, the Maselspoort, Maselspoort Resort and the :af:Sand du Plessis-teaterkompleks, Sand du Plessis Theatre. The city hosts numerous museums, including the National Women's Monument, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
