Werner Landgraf | |
|---|---|
 Werner Landgraf (1991) | |
| Born | July 29, 1959 Mainz, Germany |
| Nationality | German |
| Awards | |
| Scientific career | |
| Fields | Astrophysics, Cosmology, Fundamental Physics |
| Thesis | Nichtgravitative Kräfte beim Halleyschen Kometen (1988) |
| Doctoral advisor | Hans-Heinrich Voigt |
Werner Landgraf (born 29 July 1959, in Mainz) is a German astrophysicist and a discoverer of minor planets.
W. Landgraf studied physics at the University of Siegen in 1977 and was working on his first astronomical projects. [1] His earliest work was very inspired by Brian G. Marsden and Victor Shor. Two years later, he joined the Department of Astrophysics of University of Göttingen. There he presented his thesis The calculation of atmospheric models and line profiles for the analysis of stellar spectra. He graduated from the university in 1983, [2] and then he worked until 1988 on his dissertation Nongravitational forces of Comet Halley., [3] under supervision by Hans-Heinrich Voigt.
In 1986, W. Landgraf received a teaching position at the University of Siegen. In addition to the main lecture about astronomy and astrophysics, he gave lectures also on solar system objects and their motion, Relativity and Cosmology. [4]
W. Landgraf's work mainly concerns the verification and determination of astronomical constants of the reference system, the masses of the planets, non-gravitational forces and the verification of the gravitational law within the Solar System. He developed and improved methods for identifying and calculating the orbits of different objects in the Solar System. He busied himself in this work with numerous minor planets with emphasis on the near-Earth asteroids, comets, their long term dynamics, [5] and with the observation of small planets and comets. [5]
He also developed a method of eliminating systematic errors in positioning brighter comets that resulted in a more accurate prediction of the Halley's Comet. [6] A recalculation of the path of Halley's comet to 2317 BC confirmed that the Greeks had already seen the comet on 466 B.C. [7] [8] [9]
| 3683 Baumann | 23 June 1987 |
| 4349 Tibúrcio | 5 June 1989 |
| 4378 Voigt | 14 May 1988 |
| 7696 Liebe | 10 May 1988 |
| 9938 Kretlow | 14 May 1988 |
| 17412 Kroll | 24 May 1988 |
| 29148 Palzer | 10 May 1988 |
He discovered seven minor planets including 3683 Baumann, 4378 Voigt (named after Hans-Heinrich Voigt), 9938 Kretlow and 4349 Tibúrcio at ESO's La Silla Observatory in northern Chile. [10] [11]
He examined the properties, individuation and interaction of causets, which each starts from the affirmation that "everything what exists, acts" as its first element and as its sphere of validity successively produces really news, not predetermined by nor contained in and linear independent from old, and that the earliest elements or occurred facts and their aftereffects appear as its internal logical, geometrical, physical properties (namely, the first and the next 1,2,4 ... elements of the same rank, represent its dimensions and corresponding primary natural forces). Applied to our real world, this would suggest that successive events, world points, and their actions already would be an own discrete first dimension and producing force, corresponding to proper time (inclusive a discrete variance and limited vality range of facts and their effects), followed by the similar time; a kinematic extension, and two equivalent curvature-defining geometric extensions. This makes plausible that the dimensions of the world increase proportionally to their elementary units, in a not-localizable manner, very classically and approximately corresponding to a radiation with a wavelength of about the world's size, keeping the biggest part of the world's energy, per each elementary space inclusive at any background or surface one such photon or information and a pressure canceling the gravitational deceleration of expansion [12]
In 1987, asteroid 3132 Landgraf was named after him. [13]
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can subtend an arc of up to 30° across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
The Oort cloud, sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU. The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. The largest eight objects, which form a planetary system, are, in order of distance from the Sun: four terrestrial planets, Mercury, Venus, Earth and Mars; and four giant planets which include two gas giants, Jupiter and Saturn, and two ice giants, Uranus and Neptune. The terrestrial planets, which all have a definite surface, are mostly made of rock and metal. The gas giants are mostly made of hydrogen and helium, while the ice giants are mostly made of volatile substances such as water, ammonia, and methane. The terrestrial planets are also called the inner Solar System and the giant planets the outer Solar System.
2060 Chiron is a small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orbiting between the asteroid belt and the Kuiper belt.
Heinrich Wilhelm Matthias Olbers was a German astronomer. He found a convenient method of calculating the orbit of comets, and in 1802 and 1807 discovered the second and the fourth asteroids Pallas and Vesta.
Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to form out of cosmic dust grains. Believed to have formed in the Solar System about 4.6 billion years ago, they aid study of its formation.
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms object and body are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial object is a complex, less cohesively bound structure, which may consist of multiple bodies or even other objects with substructures.
Maximilian Franz Joseph Cornelius Wolf was a German astronomer and a pioneer in the field of astrophotography. He was the chairman of astronomy at the University of Heidelberg and director of the Heidelberg-Königstuhl State Observatory from 1902 until his death in 1932.
Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-type or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Jupiter Tisserand invariant (TJ) of 2 or less, while Akimasa Nakamura defines this group with the following orbital elements:
Armin Otto Leuschner was an American astronomer and educator.
David Clifford Jewitt is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Planetary Physics, the Director of the Institute for Planets and Exoplanets, Professor of Astronomy in the Department of Physics and Astronomy and Professor of Astronomy in the Department of Earth, Planetary and Space Sciences. He is best known for being the first person to discover a body beyond Pluto and Charon in the Kuiper belt.
Paulo Renato Centeno Holvorcem is a Brazilian amateur astronomer and mathematician who lives in Brasilia, Brazil.
The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5×109 km; 2.8×109 mi). These extreme orbits are thought to be the result of gravitational "scattering" by the gas giants, and the objects continue to be subject to perturbation by the planet Neptune.
The following outline is provided as an overview of and topical guide to astronomy:
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: "All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies' ".
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term minor planet, but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs).
D/1770 L1, popularly known as Lexell's Comet after its orbit computer Anders Johan Lexell, was a comet discovered by astronomer Charles Messier in June 1770. It is notable for having passed closer to Earth than any other comet in recorded history, approaching to a distance of only 0.015 astronomical units, or six times the distance from the Earth to the Moon. The comet has not been seen since 1770 and is considered a lost comet.
Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of two bodies. Of greatest interest is the risk of a collision with Earth. Earth MOID is often listed on comet and asteroid databases such as the JPL Small-Body Database. MOID values are also defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on.
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a significant amount of jargon.
Robert D. Stephens is an American amateur astronomer and a prolific photometrist of minor planets at the Center for Solar System Studies, Rancho Cucamonga in California, United States.
