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GPM J1839−10
GPM J1839−10 is a potentially unique ultra-long period magnetar located about 15,000 light-years away from Earth in the Scutum constellation, in the Milky Way. It was discovered by a team of scientists at Curtin University using the Murchison Widefield Array. Its unusual characteristics violate current theory and prompted a search of other radio telescope archives, including the Giant Metrewave Radio Telescope and the Very Large Array, which revealed evidence of the object dating back to 1988. The signature of the object went unnoticed because scientists did not know to look for its unusual behavior. The current understanding of neutron stars is that below a certain rate of rotation, called "the death line", they cease emissions. Uniquely, not only does GPM J1839−10 have an extremely slow rotation of approximately twenty-two minutes, it emits bursts of radio waves lasting up to five minutes, for which there is currently no generally accepted explanation. See also * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field (∼109 to 1011 T, ∼1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.Ward; Brownlee, p.286 The existence of magnetars was proposed in 1992 by Robert Duncan and . Their proposal sought to explain the properties of transient sources of gamma rays, now known as soft gamma repeaters (SGRs). Over the following decade, the magnetar hypothesis became widely accepted, and was extended to explain anomalous X-ray pulsars (AXPs). , 24 confirmed magnetars were known. It has been suggested that magnetars are the source of fast radio bursts (FRB), in particular as a result of findings in 2020 by scientists using the Australian Square Kilometre Array. Description Like other neutron stars, magnetars are around in diameter, and have a mass about 1.4 solar masses. They are formed by the collapse of a star with a mass 10– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Star
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 electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetars
A magnetar is a type of neutron star with an extremely powerful magnetic field (∼109 to 1011 T, ∼1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.Ward; Brownlee, p.286 The existence of magnetars was proposed in 1992 by Robert Duncan and . Their proposal sought to explain the properties of transient sources of gamma rays, now known as soft gamma repeaters (SGRs). Over the following decade, the magnetar hypothesis became widely accepted, and was extended to explain anomalous X-ray pulsars (AXPs). , 24 confirmed magnetars were known. It has been suggested that magnetars are the source of fast radio bursts (FRB), in particular as a result of findings in 2020 by scientists using the Australian Square Kilometre Array. Description Like other neutron stars, magnetars are around in diameter, and have a mass about 1.4 solar masses. They are formed by the collapse of a star with a mass 10– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Types
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSR J0901–4046
PSR J0901–4046 is an ultra-long period pulsar. Its period, 75.9 seconds, is the longest for any known neutron star pulsar (some objects believed to be white dwarf pulsars, such as AR Scorpii, have longer periods). Its period is more than three times longer than that of PSR J0250+5854, the previous long period record-holder. The pulses are narrow; radio emission is seen from PSR J0901–4046 for only 0.5% of its rotation period. PSR J0901–4046 was discovered serendipitously on September 27, 2020, by the MeerTRAP team, when a single pulse from it was noticed during MeerKAT observations of Vela X-1 (which is less than 1/4 degree away from PSR J0901–4046 on the sky). After that pulse was detected, further examination of the data revealed that 14 weaker pulses were present in the ~30 minute long data set, but they had been missed by the real-time detection software. The deepest image of the MeerKAT field showed a diffuse shell-like structure that may be a supernova remna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GCRT J1745−3009
GCRT J1745−3009 is a Galactic Center radio transient (GCRT), or bursting low-frequency radio source which lies in the direction of the Galactic Center.A Faint, Steep Spectrum Burst from the Radio Transient GCRT J1745-3009, Scott D. Hyman, Subhashis Roy, Sabyasachi Pal, T. Joseph W. Lazio, Paul S. Ray, Namir E. Kassim, and Sanjay BhatnagararXiv:astro-ph/0701098 Discovery A group of astronomers from Sweet Briar College and the Naval Research Laboratory detected transient emission from two sources in 1998 while studying the Galactic Center. They then began monitoring the region specifically looking for transient sources and detected five bursts of radio waves about 1 meter in wavelength (frequency 330 MHz) during a seven-hour period from September 30 to October 1, 2002. The five bursts were of equal brightness, with each lasting about 10 minutes, and occurring every 77 minutes. Like an earlier low-frequency transient discovered by the same group, it was given the desig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the ''Timaeus'' of Plato, or Socrates in his reflections on what the Greeks called ''khôra'' (i.e. "space"), or in the ''Physics'' of Aristotle (Book IV, Delta) in the definition of ''topos'' (i.e. place), or in the later "geometrical conception of place" as "spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Large Array
The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~ west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes (twenty-seven of which are operational while one is always rotating through maintenance) deployed in a Y-shaped array and all the equipment, instrumentation, and computing power to function as an interferometer. Each of the massive telescopes is mounted on double parallel railroad tracks, so the radius and density of the array can be transformed to adjust the balance between its angular resolution and its surface brightness sensitivity. Astronomers using the VLA have made key observations of black holes and protoplanetary disks around young stars, discovered magnetic filaments and traced complex gas motions at the Milky Way's center, probed the Universe's cosmological parameters, and provided new knowled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Metrewave Radio Telescope
The Giant Metrewave Radio Telescope (GMRT), located near Pune, Junnar, near Narayangaon at khodad in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research, Mumbai. It was conceived and built under the direction of Late Prof. Govind Swarup during 1984 to 1996. It is an interferometric array with baselines of up to . It was recently upgraded with new receivers, after which it is also known as the Upgraded Giant Metrewave Radio Telescope (uGMRT). Location The GMRT Observatory is located about 80 km north of Pune at Khodad. A nearby town is Narayangaon which is around 9 km from the telescope site. The office of NCRA is located in the Savitribai Phule Pune University campus. Science and observations One of the aims for the telescope during its development was to search for the highl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Telescopes
A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night. Since astronomical radio sources such as planets, stars, nebulas and galaxies are very far away, the radio waves coming from them are extremely weak, so radio telescopes require very large antennas to collect enough radio energy to study them, and extremely sensitive receiving equipment. Radio telescopes are typically large parabolic ("dish") antennas similar to those employed in tracking and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
