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V777 Her
GD 358 is a variable white dwarf star of the DBV type. Like other pulsating white dwarfs, its variability arises from non-radial gravity wave pulsations within the star itself. GD 358 was discovered during the 1958–1970 Lowell Observatory survey for high proper motion stars in the Northern Hemisphere. Although it did not have high proper motion, it was noticed that it was a very blue star, and hence might be a white dwarf. Greenstein confirmed this in 1969. In 1968, Arlo U. Landolt discovered the first intrinsically variable white dwarf when he found that HL Tau 76 varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes.A New Short-Period Blue Variable Arlo U. Landolt, ''Astrophysical Journal'' 153, #1 (July 1968), pp. 151–164. By the middle of the 1970s, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965. and In 2011, the Observatory was named one of "The World's 100 Most Important Places" by Time Magazine. It was at the Lowell Observatory that the dwarf planet Pluto was discovered in 1930 by Clyde Tombaugh. The observatory was founded by astronomer Percival Lowell of Boston's Lowell family and is overseen by a sole trustee, a position historically handed down through the family. The first trustee was Lowell's third cousin Guy Lowell (1916–1927). Percival's nephew Roger Putnam served from 1927 to 1967, followed by Roger's son Michael (1967–1987), Michael's brother William Lowell Putnam III (1987–2013), and current trustee W. Lowell Putnam. Multiple astronauts attended the Lowell Observatory in 1963 while the moon was being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable-star
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] |
Don Winget
Don E. Winget is an American astronomer and astrophysicist who studies white dwarf stars. He is the Harlan J. Smith Centennial Professor in Astronomy and a university distinguished teaching professor at the University of Texas at Austin. Research Much of Winget's research concerns the study of white dwarf stars. Winget's doctoral research at the University of Rochester predicted the existence of DBV stars, a certain class of pulsating white dwarf. After becoming a faculty member at the University of Texas, he and his colleagues discovered GD 358, a star of this class, fulfilling the prediction of his dissertation and marking the first time in which a class of variable stars was predicted to exist before any instances of it were observed. With Ed Nather, his colleague at University of Texas, Winget introduced the technique for studying the seismology and the inner structure of white dwarfs called "Whole Earth Telescope". The technique involves coordinating a network of small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Dwarf Spectroscopy
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, 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 Thermal radiation, emission of residual heat, 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 stellar evolution, 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-stellar nucleosynthesis, fusing period of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HL Tau 76
HL Tau 76 is a variable white dwarf star of the DAV (or ZZ Ceti) type. It was observed by G. Haro and W. J. Luyten in 1961, and was the first variable white dwarf discovered when, in 1968, Arlo U. Landolt found that it varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes. Like other DAV white dwarfs, its variability arises from non-radial gravity wave pulsations within itself., § 7. Later observation and analysis has found HL Tau 76 to pulsate in over 40 independent vibrational modes, with periods between 380 seconds and 1390 seconds. The designation HL Tau 76 derives from the discovery of this star as a white dwarf, when it was described as ''Taurus no.76'' in a publication authored by Guillermo Haro and Willem Jacob Luyten. The exact designation ''HL Tau 76'' was then used in subsequent papers, including one giving the star its designation EGGR 265 where it was noted to be variable. It was then included in the 57th name-list of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arlo U
Arlo (pronounced AR-loh) is a traditionally male given name. Some sources state it to be of Old English origin, meaning "from the hill fort"; it was first used by Edmund Spenser, who "evidently invented" it, as the name of a hill where the gods debate in his poem ''The Faerie Queene'' (1590 and 1596). A 2018 Yahoo! UK article indicated an increasing popularity of "Arlo" – alongside such names as "James", "Charlie", "Noah", and "Reggie" as a girls' name in England and Wales. {{tocright People Arts and sciences * Arlo Bates (1850–1918), American author, educator and newspaperman * Arlo Gilliam (born 1977), American singer-songwriter and record producer * Arlo Guthrie (born 1947), American folk singer * Arlo Haskell, historian, poet, literary organizer, and publisher * Arlo Hemphill (born 1971), American explorer, ocean conservationist and film actor * Arlo U. Landolt (1935–2022), American astronomer * Arlo Parks (born 2000), British musician * Arlo West (born 1958), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jesse L
Jesse may refer to: People and fictional characters * Jesse (biblical figure), father of David in the Bible. * Jesse (given name), including a list of people and fictional characters * Jesse (surname), a list of people Music * ''Jesse'' (album), a 2003 album by Jesse Powell * "Jesse", a 1973 song by Roberta Flack - see Roberta Flack discography * "Jesse", a song from the album ''Valotte'' by Julian Lennon * "Jesse", a song from the album ''The People Tree'' by Mother Earth * "Jesse" (Carly Simon song), a 1980 song * "Jesse", a song from the album ''The Drift'' by Scott Walker * "Jesse", a song from the album '' If I Were Your Woman'' by Stephanie Mills Other * ''Jesse'' (film), a 1988 American television film * ''Jesse'' (TV series), a sitcom starring Christina Applegate * ''Jesse'' (novel), a 1994 novel by Gary Soto * ''Jesse'' (picture book), a 1988 children's book by Tim Winton * Jesse, West Virginia, an unincorporated community * Jesse Hall, University of Missouri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to Earth's axial tilt of 23.439281°, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation. Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to the Coriolis e ... [...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] |
Gravity Wave
In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. An example of such an interface is that between the atmosphere and the ocean, which gives rise to wind waves. A gravity wave results when fluid is displaced from a position of equilibrium. The restoration of the fluid to equilibrium will produce a movement of the fluid back and forth, called a ''wave orbit''. Gravity waves on an air–sea interface of the ocean are called surface gravity waves (a type of surface wave), while gravity waves that are the body of the water (such as between parts of different densities) are called ''internal waves''. Wind-generated waves on the water surface are examples of gravity waves, as are tsunamis and ocean tides. The period of wind-generated gravity waves on the free surface of the Earth's ponds, lakes, seas and oceans are predominantly between 0.3 and 30 secon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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