Magnetar

A magnetar is a rare compact type of neutron star teeming with high energy and magnetism. They experience violent eruptions or intense bursts in the form of transient X-ray pulses which are several orders higher than that of the Sun.
Magnetars are relatively rare objects, with only about thirty having been spotted within the Milky Way so far.

An international group of researchers has succeeded in measuring for the first time the characteristics of a flare on a distant magnetar.
The team includes astronomers from Norway, Spain and the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital.
The magnetar they have studied is about 13 million light years away, in the direction of the NGC 253, a prominent galaxy in the Sculptor group of galaxies.
Scientists involved in the research say that the single event released energy equivalent to what the Sun would radiate in one lakh years.

During the course of their evolution, massive stars – with masses around 10-25 times the mass of the Sun – eventually collapse and shrink to form very compact objects called neutron stars. A subset of these neutron stars are the so-called magnetars which possess intense magnetic fields. These are highly dense and have breathtakingly high rotation speeds – they have rotational periods that can be just 0.3 to 12.0 seconds.
Magnetars have high magnetic fields in the range of 1015 gauss and they emit energy in the range given by luminosities of 1037 – 1040 joules per second. Compare this to the luminosity of the sun which is in the order of 1026 joules per second.

Eruptions in magnetars are believed to be due to instabilities in their magnetosphere, or “starquakes” produced in their crust – a rigid, elastic layer about one kilometre thick. This causes waves in the magnetosphere, and interaction between these waves causes dissipation of energy.
This instability triggers Alfven waves that are also common in the Sun. The interactions between multiple Alfven waves ultimately release massive energies, appearing as giant flares lasting for a few milliseconds.
Magnetars are very difficult to observe when they are silent. It is only during a flare that they can be observed, and these flares are so short-lived that it presents a formidable problem.
This is the first extragalactic magnetar that has been thoroughly researched.
Comprehension of these eruptions can give information on the structure of these enigmatic things.
The finding might open the path for future research into how magnetic stresses are generated around neutron stars.

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