An international group of researchers has succeeded in measuring for the first time the characteristics of a flare on a distant magnetar.
What is a Magnetar?
- Magnetars are the most magnetic stars in the universe.
- It is a rare compact type of neutron star teeming with energy and magnetism.
- It is an exotic type of neutron star, its defining feature that it has an ultra-powerful magnetic field.
- The field is about 1,000 times stronger than a normal neutron star and about a trillion times stronger than the Earth’s.
- Magnetars are relatively rare objects, with only about thirty having been spotted within the Milky Way so far.
What is the recent study?
- The studied magnetar is about 13 million light years away, in the direction of the NGC 253, a prominent galaxy in the Sculptor group of galaxies.
- Its flare spewed within a few tenths of a second as much energy as the Sun would shed in 100,000 years.
- It was captured accidentally on April 15, 2020, by the Atmosphere-Space Interactions Monitor instrument (ASIM) of the International Space Station.
- This is the first study to characterize such a flare from so distant a magnetar.
How do magnetars form?
- 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 is 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.
What characterizes Magnetars?
(1) Violent flares
- The observed giant flare lasted approximately 160 milliseconds and during this time 1039 joules of energy was released.
- The flare spewed as much energy in a tenth of a second that our Sun will radiate in 100,000 years.
(2) Starquakes
- 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 kilometer thick.
- This causes waves in the magnetosphere, and interaction between these waves causes dissipation of energy.
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