SGR J1550-5418
Encyclopedia
SGR J1550-5418 is a soft gamma-ray 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 last year, as well as in X-ray and radio emission.
It has been observed to emit intense bursts of gamma ray
s at a rate of up to several per minute.
At its estimated distance of 30,000 light years (~10 kpc), the most intense flares equal the total energy emission of the Sun in ~20 years.
The underlying object is believed to be a rotating neutron star
, of the type known as magnetar
s, which have magnetic fields up to 1015 gauss, about 1000 times that of more typical neutron star X-ray sources. See Orders of magnitude (magnetic field) for examples of other magnetic field strengths.
The rotation period, ~2.07 s, is the fastest yet observed for a magnetar.
The first observation of "Light echo
s" from a gamma-ray source, a phenomenon long known for visible stars such as nova
s, have been observed from SGR J1550-5418.
The location of SGR J1550-5418 (aka AXP
1E 1547.0-5408) , is RA(J2000) = 15h50m54.11s, Dec(J2000) = -54°18´23.7´´.
Soft gamma repeater
A soft gamma repeater is an astronomical object which emits large bursts of gamma-rays and X-rays at irregular intervals. It is conjectured that they are a type of magnetar or, alternatively, neutron stars with fossil disks around them....
(SGR), the sixth to be discovered, located in the constellation Norma
Norma (constellation)
Norma is a small and inconspicuous constellation in the southern hemisphere between Scorpius and Centaurus. Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenter's square, a set square or a level....
.
Long known as an X-ray source
X-ray source
X-ray sources abound around us.* an astronomical X-ray source, see X-ray astronomy** X-ray background* an X-ray tube, artificial X-ray source* synchrotrons, which produce X-rays as synchrotron radiation...
, 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
Swift Gamma-Ray Burst Mission
The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 20 November 2004, 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international...
satellite, and by the Fermi Gamma-ray Space Telescope, launched last year, as well as in X-ray and radio emission.
It has been observed to emit intense bursts of gamma ray
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
s at a rate of up to several per minute.
At its estimated distance of 30,000 light years (~10 kpc), the most intense flares equal the total energy emission of the Sun in ~20 years.
The underlying object is believed to be a rotating neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
, of the type known as magnetar
Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field, the decay of which powers the emission of copious high-energy electromagnetic radiation, particularly X-rays and gamma rays...
s, which have magnetic fields up to 1015 gauss, about 1000 times that of more typical neutron star X-ray sources. See Orders of magnitude (magnetic field) for examples of other magnetic field strengths.
The rotation period, ~2.07 s, is the fastest yet observed for a magnetar.
The first observation of "Light echo
Light echo
thumb|right|250px|Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from [[Earth]]....
s" from a gamma-ray source, a phenomenon long known for visible stars such as nova
Nova
A nova is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner...
s, have been observed from SGR J1550-5418.
The location of SGR J1550-5418 (aka AXP
Anomalous X-ray pulsar
Anomalous X-ray Pulsars 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 . There are currently 9 known and 1 candidate...
1E 1547.0-5408) , is RA(J2000) = 15h50m54.11s, Dec(J2000) = -54°18´23.7´´.