|
Hercules X-1
Hercules X-1 (Her X-1), also known as 4U1656+35, is a moderately strong X-ray binary source first studied by the Uhuru satellite. It is composed of a neutron star accreting matter from a normal star (HZ Her) probably due to Roche lobe overflow. Intermediate-mass X-ray binary (IMXB) Her X-1 is the prototype for the massive X-ray binaries although it falls on the borderline, , between high- and low-mass X-ray binaries. An intermediate-mass X-ray binary (IMXB) is a binary star system where one of the components is a neutron star or a black hole. The other component is an intermediate mass star. Intensity The source exhibits complex time variability, pulsing with a period of 1.24 s due to the rotation of the neutron star, eclipsing every 1.70 days with the period of the binary orbit, and also varying with a 35-day period believed associated with the precession of the accretion disk. From observations, a twisted accretion disk, in retrograde precession, modulates the X-rays ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hercules (constellation)
Hercules is a constellation named after Hercules, the Roman mythology, Roman mythological hero adapted from the Greek mythology, Greek hero Heracles. Hercules was one of the 48 constellations listed by the second-century astronomer Ptolemy, and it remains one of the IAU designated constellations, 88 modern constellations today. It is the fifth-largest of the modern constellations and is the largest of List of brightest stars, the 50 which have no stars brighter than apparent Magnitude (astronomy), magnitude +2.5. Characteristics Hercules is bordered by Draco (constellation), Draco to the north; Boötes, Corona Borealis, and Serpens, Serpens Caput to the east; Ophiuchus to the south; Aquila (constellation), Aquila to the southwest; and Sagitta, Vulpecula, and Lyra to the west. Covering 1225.1 square degrees and 2.970% of the night sky, it ranks fifth among the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical X-ray Sources
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. Several types of astrophysical objects emit X-rays. They include galaxy clusters, black holes in active galactic nuclei (AGN), galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf (cataclysmic variable stars and super soft X-ray sources), neutron star or black hole (X-ray binaries). Some Solar System bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays. Furthermore, celestial entities in space are discussed as celestial X-ray sources. The origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background. The X-ray continuum can ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Stars
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white holes, quark stars, and strange stars), neutron stars are the smallest and densest currently known class of stellar objects. Neutron stars have a radius on the order of and a mass of about 1.4 solar masses. 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. Once formed, they no longer actively generate heat, and cool over time; however, they may still evolve further through collision or accretion. Most of the basic models for these objects imply that neutron stars are composed almost entirely of neutrons (subatomic particles with no net electrical charge and with slightly larger mass than protons); the electron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OSO 7
OSO 7 or Orbiting Solar Observatory 7 (NSSDC ID: 1971-083A), before launch known as OSO H is the seventh in the series of American Orbiting Solar Observatory satellites launched by NASA between 1962 and 1975. OSO 7 was launched from Cape Kennedy (now Cape Canaveral) on 29 September 1971 by a Delta N rocket into a 33.1° inclination, low-Earth (initially 321 by 572 km) orbit, and re-entered the Earth's atmosphere on 9 July 1974. It was built by the Ball Brothers Research Corporation (BBRC), now known as Ball Aerospace, in Boulder Colorado. While the basic design of all the OSO satellites was similar, the OSO 7 was larger otal spacecraft mass was 635 kg (1397 lb)than the OSO 1 through OSO 6, with a larger squared-off solar array in the non-rotating "Sail", and a deeper rotating section, the "Wheel". Sail instruments The "Sail" portion of the spacecraft, which was stabilized to face the Sun in all the OSO series satellites, carried two instruments on OSO 7, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the celestial equator, along the hour circle passing through the point in question. The root of the word ''declination'' (Latin, ''declinatio'') means "a bending away" or "a bending down". It comes from the same root as the words ''incline'' ("bend foward") and ''recline'' ("bend backward"). In some 18th and 19th century astronomical texts, declination is given as ''North Pole Distance'' (N.P.D.), which is equivalent to 90 – (declination). For instance an object marked as declination −5 would have an N.P.D. of 95, and a declination of −90 (the south celestial pole) would have an N.P.D. of 180. Explanation Declination in astronomy is comparable to geographic latitude, projected onto the celestial sphere, and right ascension is like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right Ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired with declination, these astronomical coordinates specify the location of a point on the celestial sphere in the equatorial coordinate system. An old term, ''right ascension'' ( la, ascensio recta), "''Ascensio recta'' Solis, stellæ, aut alterius cujusdam signi, est gradus æquatorus cum quo simul exoritur in sphæra recta"; roughly translated, "''Right ascension'' of the Sun, stars, or any other sign, is the degree of the equator that rises together in a right sphere" refers to the ''ascension'', or the point on the celestial equator that rises with any celestial object as seen from Earth's equator, where the celestial equator intersects the horizon at a right angle. It contrasts with ''oblique ascension'', the point on the celestial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Juan, Puerto Rico
San Juan (, , ; Spanish for "Saint John") is the capital city and most populous municipality in the Commonwealth of Puerto Rico, an unincorporated territory of the United States. As of the 2020 census, it is the 57th-largest city under the jurisdiction of the United States, with a population of 342,259. San Juan was founded by Spanish colonists in 1521, who called it Ciudad de Puerto Rico ("City of Puerto Rico", Spanish for ''rich port city''). Puerto Rico's capital is the third oldest European-established capital city in the Americas, after Santo Domingo, in the Dominican Republic, founded in 1496, and Panama City, in Panama, founded in 1521, and is the oldest European-established city under United States sovereignty. Several historical buildings are located in San Juan; among the most notable are the city's former defensive forts, Fort San Felipe del Morro and Fort San Cristóbal, and La Fortaleza, the oldest executive mansion in continuous use in the Americas. Today, Sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket Graph
A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the vacuum of space. Rockets work more efficiently in a vacuum and incur a loss of thrust due to the opposing pressure of the atmosphere. Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets rely on momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, spin, or gravity. Rockets for military and recreational uses date back to at least 13th-century China. Signif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma (physics)
Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ is the electron collision rate. It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are ''anisotropic'', meaning that their properties in the direction parallel to the magnetic field are different from those perpendicular to it. While electric fields in plasmas are usually small due to the plasma high conductivity, the electric field associated with a plasma moving with velocity \mathbf in the magnetic field \mathbf is given by the usual Lorentz force, Lorentz formula \mathbf = -\mathbf\times\mathbf, and is not affected by Debye shielding. Mathematical descriptions To completely describe the state of a plasma, all of the particle locations and velocities that describe the electromagnetic field in the plasma region would need to be written down. However, it is generally not practical or necessary to keep track of all the particles in a plasma. Therefore, plasma physicist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
