MAGNETARS

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Context

• Huge energetic flare from magnetic neutron star detected.
• Scientists have now detected the most distant-known instance of one of these eruptions, called a giant flare, from a magnetar residing in a galaxy called Messier 82, or M82.
• Unleashed in just a tenth of a second an energy equivalent to the Sun's output over roughly 10,000 years.

Details

Characteristics of M82

• Located 12 million light-years away in the Ursa Major constellation.
• Known as the "cigar galaxy" due to its elongated shape when viewed edge-on.
• Exhibits high rates of star formation, making it an active "starburst galaxy."

Giant Flares

• Rare eruptions of gamma rays, releasing immense energy.
• Giant flares are infrequent, with only two confirmed instances observed in the Milky Way and one in the neighboring Large Magellanic Cloud prior to this discovery.
• Despite at least 30 known magnetars in the Milky Way, giant flares are rarely observed events.
• Giant Flare Mechanism: Originates from reconfiguration and reconnection of the magnetar's magnetic field.

Neutron Stars

• Neutron stars are born from the explosive collapse of massive stars.
• Remarkably dense, compressing one or two solar masses into a sphere the size of a city.

Magnetars

• Magnetars are a type of neutron star characterized by extremely strong magnetic fields, among the most powerful observed in the universe.
• Powered by their own magnetic energy, distinguishing them from ordinary neutron stars.
• Magnetars are relatively small and dense objects, with diameters of about 10-15 kilometers, similar to other neutron stars.

Characteristics:

Strong Magnetic Fields:

• Magnetars have magnetic field strengths ranging from 1,000 to 10,000 trillion Gauss (for comparison, Earth's magnetic field is about 0.5 Gauss).
• These intense magnetic fields distort the structure of the neutron star and exert powerful forces on its surroundings.

Rapid Rotation:

• Magnetars typically rotate rapidly, with periods ranging from a few seconds to several seconds.
• Rapid rotation, coupled with strong magnetic fields, generates intense electromagnetic radiation and energy release.

Formation of Magnetars:

• Magnetars are believed to form from the remnants of massive stars that undergo supernova explosions.
• The collapse of the star's core during the supernova process results in the formation of a neutron star.
• If the progenitor star had a sufficiently strong magnetic field, the neutron star may become a magnetar.

Observed Phenomena:

• Magnetars are known for their sporadic and intense bursts of X-ray and gamma-ray radiation.
• These bursts can be thousands of times more energetic than typical neutron star emissions and are thought to result from sudden releases of magnetic energy.
• Magnetars experience seismic-like disturbances called "magnetar quakes" or "starquakes."
• These events occur when the magnetic field undergoes a sudden reconfiguration, leading to seismic waves in the neutron star's crust.
• Some magnetars have been associated with gamma-ray bursts (GRBs), the most energetic explosions in the universe.
• The exact mechanism by which magnetars produce GRBs is still under investigation but is thought to involve the restructuring of the magnetic field or the collapse of the neutron star's crust.

Sources:

Hindu

PRACTICE QUESTION Q.  Discuss the significance of magnetars in astrophysics and their contribution to our understanding of extreme celestial phenomena. (250 words)