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A neutron star is the collapsed core of a massive supergiant star,which had a total mass of between 10 and 25 solar masses (M☉),possibly more if the star was especially metal-rich. Except for black holes,neutron stars are the smallest and densest known class of stellar objects. Neutron stars have a radius on the order of 10 kilometers (6 mi) and a mass of about 1.4 M☉. They result from the supernova explosion of a massive star,combined with gravitational collapse,that compresses the core past white dwarf star density to that of atomic nuclei.
PSR B1620−26 b is an exoplanet located approximately 12,400 light-years from Earth in the constellation of Scorpius. It bears the unofficial nicknames "Methuselah" and "the Genesis planet" due to its extreme age. The planet is in a circumbinary orbit around the two stars of PSR B1620−26 and is the first circumbinary planet ever confirmed. It is also the first planet found in a globular cluster. The planet is one of the oldest known extrasolar planets,believed to be about 12.7 billion years old.
Sergei Kopeikin is a USSR-born theoretical physicist and astronomer presently living and working in the United States,where he holds the position of Professor of Physics at the University of Missouri in Columbia,Missouri. He specializes in the theoretical and experimental study of gravity and general relativity. He is also an expert in the field of the astronomical reference frames and time metrology. His general relativistic theory of the Post-Newtonian reference frames which he had worked out along with Victor A. Brumberg,was adopted in 2000 by the resolutions of the International Astronomical Union as a standard for reduction of ground-based astronomical observation. A computer program Tempo2 used to analyze radio observations of pulsars,includes several effects predicted by S. Kopeikin that are important for measuring parameters of the binary pulsars,for testing general relativity,and for detection of gravitational waves of ultra-low frequency. Sergei Kopeikin has worked out a complete post-Newtonian theory of equations of motion of N extended bodies in scalar-tensor theory of gravity with all mass and spin multipole moments of arbitrary order and derived the Lagrangian of the relativistic N-body problem.
Joseph Hooton Taylor Jr. is an American astrophysicist and Nobel Prize laureate in Physics for his discovery with Russell Alan Hulse of a "new type of pulsar,a discovery that has opened up new possibilities for the study of gravitation."
Russell Alan Hulse is an American physicist and winner of the Nobel Prize in Physics,shared with his thesis advisor Joseph Hooton Taylor Jr.,"for the discovery of a new type of pulsar,a discovery that has opened up new possibilities for the study of gravitation".
PSR B1620−26 is a binary star system located at a distance of 3,800 parsecs in the globular cluster of Messier 4 in the constellation of Scorpius. The system is composed of a pulsar and a white dwarf star. As of 2000,the system is also confirmed to have an exoplanet orbiting the two stars.
A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth,and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short,regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
A millisecond pulsar (MSP) is a pulsar with a rotational period less than about 10 milliseconds. Millisecond pulsars have been detected in radio,X-ray,and gamma ray portions of the electromagnetic spectrum. The leading theory for the origin of millisecond pulsars is that they are old,rapidly rotating neutron stars that have been spun up or "recycled" through accretion of matter from a companion star in a close binary system. For this reason,millisecond pulsars are sometimes called recycled pulsars.
PSR J0737−3039 is the first known double pulsar. It consists of two neutron stars emitting electromagnetic waves in the radio wavelength in a relativistic binary system. The two pulsars are known as PSR J0737−3039A and PSR J0737−3039B. It was discovered in 2003 at Australia's Parkes Observatory by an international team led by the Italian radio astronomer Marta Burgay during a high-latitude pulsar survey.
The Hulse–Taylor pulsar is a binary star system composed of a neutron star and a pulsar which orbit around their common center of mass. It is the first binary pulsar ever discovered.
The gravitational wave background is a random background of gravitational waves permeating the Universe,which is detectable by gravitational-wave experiments,like pulsar timing arrays. The signal may be intrinsically random,like from stochastic processes in the early Universe,or may be produced by an incoherent superposition of a large number of weak independent unresolved gravitational-wave sources,like supermassive black-hole binaries. Detecting the gravitational wave background can provide information that is inaccessible by any other means,about astrophysical source population,like hypothetical ancient supermassive black-hole binaries,and early Universe processes,like hypothetical primordial inflation and cosmic strings.
A binary pulsar is a pulsar with a binary companion,often a white dwarf or neutron star. Binary pulsars are one of the few objects which allow physicists to test general relativity because of the strong gravitational fields in their vicinities. Although the binary companion to the pulsar is usually difficult or impossible to observe directly,its presence can be deduced from the timing of the pulses from the pulsar itself,which can be measured with extraordinary accuracy by radio telescopes.
Gravitational waves are waves of the intensity of gravity that are generated by the accelerated masses of binary stars and other motions of gravitating masses,and propagate as waves outward from their source at the speed of light. They were first proposed by Oliver Heaviside in 1893 and then later by Henri Poincaréin 1905 as the gravitational equivalent of electromagnetic waves.
Gravitational-wave astronomy is an emerging field of science,concerning the observations of gravitational waves to collect relatively unique data and make inferences about objects such as neutron stars and black holes,events such as supernovae,and processes including those of the early universe shortly after the Big Bang.
Donald Charles Backer was an American astrophysicist who primarily worked in radio astronomy. Backer made important contributions to the understanding and study of pulsars,black holes,and the epoch of reionization.
A pulsar timing array (PTA) is a set of galactic pulsars that is monitored and analysed to search for correlated signatures in the pulse arrival times on Earth. As such,they are galactic-sized detectors. Although there are many applications for pulsar timing arrays,the best known is the use of an array of millisecond pulsars to detect and analyse long-wavelength gravitational wave background. Such a detection would entail a detailed measurement of a gravitational wave (GW) signature,like the GW-induced quadrupolar correlation between arrival times of pulses emitted by different millisecond pulsar pairings that depends only on the pairings' angular separations in the sky. Larger arrays may be better for GW detection because the quadrupolar spatial correlations induced by GWs can be better sampled by many more pulsar pairings. With such a GW detection,millisecond pulsar timing arrays would open a new low-frequency window in gravitational-wave astronomy to peer into potential ancient astrophysical sources and early Universe processes,inaccessible by any other means.
Problem books are textbooks,usually at advanced undergraduate or post-graduate level,in which the material is organized as a series of problems,each with a complete solution given. Problem books are distinct from workbooks in that the problems are designed as a primary means of teaching,not merely for practice on material learned elsewhere. Problem books are found most often in the mathematical and physical sciences;they have a strong tradition within the Russian educational system.
PSR J0348+0432 is a pulsar–white dwarf binary system in the constellation Taurus. It was discovered in 2007 with the National Radio Astronomy Observatory's Robert C. Byrd Green Bank Telescope in a drift-scan survey.
Ajit Kembhavi is an Indian astrophysicist. He is presently a Professor Emeritus at the Inter-University Centre for Astronomy and Astrophysics,(IUCAA) at Pune,India,of which he was also a founder member. He also serves as a Vice President of the International Astronomical Union. He is the Principal Investigator of Pune Knowledge Cluster along with Professor L. S. Shashidhara.
Ingrid Stairs is a Canadian astronomer currently based at the University of British Columbia. She studies pulsars and their companions as a way to study binary pulsar evolution,pulsar instrumentation and polarimetry,and Fast Radio Bursts (FRBs). She was awarded the 2017 Rutherford Memorial Medal for physics of the Royal Society of Canada,and was elected as a Fellow of the American Physical Society in 2018.
References
- 1 2 3 4 5 Much, Justin (May 14, 2011). "New Willamette U. president returns to deep roots in Salem". Statesman Journal. Retrieved May 14, 2011.[ permanent dead link ]
- ↑ Graves, Bill; Emily E. Smith (May 14, 2011). "UC Santa Cruz dean Stephen E. Thorsett will be next president of Willamette University in Salem". The Oregonian . Retrieved May 14, 2011.
- 1 2 3 4 Much, Justin (May 14, 2011). "Willamette University announces new president". Statesman Journal . Retrieved May 14, 2011.
- ↑ Thorsett, Stephen Erik (1991). Observing millisecond and binary pulsars.
- ↑ Nathan Newbury, John Ruhl, Suzanne Staggs, Stephen Thorsett, and Michael Newman. (1991). Princeton Problems in Physics with Solutions, Princeton University Press. ISBN 0-691-02449-9
- ↑ "Stephen Thorsett named dean".
- ↑ Stairs, I. H.; Thorsett, S. E.; Arzoumanian, Z. (2004). "Measurement of Gravitational Spin-Orbit Coupling in a Binary-Pulsar System". Physical Review Letters. 93 (14): 141101. arXiv: astro-ph/0408457 . Bibcode:2004PhRvL..93n1101S. doi:10.1103/PhysRevLett.93.141101. hdl:2060/20040171632. PMID 15524779. S2CID 39128728.
- ↑ Planets around Pulsars (vol. 36, 1993), ISBN 0-937707-55-4.
- ↑ Radio Pulsars (vol. 302, 2003), ISBN 1-58381-151-6.
- ↑ Extreme Solar Systems (vol. 398, 2008), ISBN 978-1-58381-666-0.
