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A magnetar is a type of neutron star believed to have 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. The theory regarding these objects was proposed by Robert Duncan and Christopher Thompson in 1992, but the first recorded burst of gamma rays thought to have been from a magnetar had been detected on March 5, 1979. During the following decade, the magnetar hypothesis became widely accepted as a likely explanation for soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). On 1 June 2020, astronomers reported narrowing down the source of fast radio bursts (FRBs), which may now plausibly include "compact-object mergers and magnetars arising from normal core collapse supernovae".
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AXP may refer to:
Anomalous X-ray pulsars (AXPs) are now widely believed to be magnetars—young, isolated, highly magnetized neutron stars. These energetic X-ray pulsars are characterized by slow rotation periods of ~2–12 seconds and large magnetic fields of ~1013–1015 gauss (1 to 100 gigateslas). There are currently (as of 2017) 12 confirmed and 2 candidate AXPs. The identification of AXPs with magnetars was motivated by their similarity to another enigmatic class of sources, the soft gamma repeaters.
SGR 1806−20 is a magnetar, a type of neutron star with a very powerful magnetic field, that was discovered in 1979 and identified as a soft gamma repeater. SGR 1806−20 is located about 14.5 kiloparsecs (50,000 light-years) from Earth on the far side of the Milky Way in the constellation of Sagittarius. It has a diameter of no more than 20 kilometres (12 mi) and rotates on its axis every 7.5 seconds (30,000 km/h rotation speed at the surface). As of 2016, SGR 1806-20 is the most highly magnetized object ever observed, with a magnetic field over 1015 gauss (G) (1011 tesla) in intensity (compared to the Sun's 1–5 G and Earth's 0.25–0.65 G).
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DEC 3000 AXP was the name given to a series of computer workstations and servers, produced from 1992 to around 1995 by Digital Equipment Corporation. The DEC 3000 AXP series formed part of the first generation of computer systems based on the 64-bit Alpha AXP architecture. Supported operating systems for the DEC 3000 AXP series were DEC OSF/1 AXP and OpenVMS AXP.
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The DECpc AXP 150, code-named Jensen, is an entry-level workstation developed and manufactured by Digital Equipment Corporation. Introduced on 25 May 1993, the DECpc AXP 150 was the first Alpha-based system to support the Windows NT operating system and the basis for the DEC 2000 AXP entry-level servers. It was discontinued on 28 February 1994, succeeded by the entry-level Multia and the entry-level and mid-range models of the AlphaStation family. The charter for the development and production of the DEC 2000 AXP was held by Digital's Entry Level Solutions Business, based in Ayr, Scotland.
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The DEC 7000 AXP and DEC 10000 AXP are a series of high-end multiprocessor server computers developed and manufactured by Digital Equipment Corporation, introduced on 10 November 1992. These systems formed part of the first generation of systems based on the 64-bit Alpha AXP architecture and at the time of introduction, ran Digital's OpenVMS AXP operating system, with DEC OSF/1 AXP available in March 1993. They were designed in parallel with the VAX 7000 and VAX 10000 minicomputers, and are identical except for the processor module(s) and supported bus interfaces. A field upgrade from a VAX 7000/10000 to a DEC 7000/10000 AXP was possible by means of swapping the processor boards.
The VAX 7000 and VAX 10000 were a series of high-end multiprocessor minicomputers developed and manufactured by Digital Equipment Corporation (DEC), introduced in July 1992. These systems used NVAX microprocessors implementing the VAX instruction set architecture (ISA). These computers ran Digital's OpenVMS operating system.
SGR J1550−5418 is a soft gamma repeater (SGR), the sixth to be discovered, located in the constellation Norma. Long known as an X-ray source, it was noticed to have become active on 23 October 2008, and then after a relatively quiescent interval, became much more active on 22 January 2009. It has been observed by the Swift satellite, and by the Fermi Gamma-ray Space Telescope, launched in 2008, as well as in X-ray and radio emission. It has been observed to emit intense bursts of gamma rays at a rate of up to several per minute. At its estimated distance of 30,000 light years, the most intense flares equal the total energy emission of the Sun in ~20 years.
SGR 0501+4516 is a soft gamma repeater (SGR), and is an ancient stellar remnant. Currently, the phenomenons of SGRs and the related Anomalous X-ray pulsars (AXP) are explained as arising from magnetars. SGR 0501+4516 is located approximately 15,000 light years from Earth and has a magnetic field 100 trillion times stronger than the Earth's.
References
- 1 2 3 "1E 1048.1-5937". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 27 November 2016.
- ↑ (in English) F. D. Seward & P. A. Charles, A Six-Second Periodic X-ray Source in Carina, Bulletin of the American Astronomical Society , 16, 983 (1984) Voir en ligne.
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