A star superimán or magnetar is a cosmic magnet. These types of stars are stellar “corpses” whose magnetic field is about a billion times stronger than Earth’s.
Summary
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- 1 Discovery
- 2 Magnetar
- 3 Stellar Corpses
- 4 The life of a star
- 1 Pending unknowns
- 5 External links
Discovery
Astronomers led by Ben Ritchie, from the Open University in Milton Keynes, in the United Kingdom – with the help of the Very Large Telescope, of the European Southern Observatory (in Chile) -, analyzed the star cluster Westerlund 1, located in the southern constellation of Ara , about 16,000 light years . In addition to hundreds of giant suns, they discovered a very rare object: a magnetar.
Magnetostar
Astronomers have found an enigmatic neutron star, whose magnetic field is billions of times stronger than the Sun’s. So much so that it could wipe a credit card 160,000 kilometers away.
It is called a magnetar (magnetic star) and is known as AXP (Anomalous X-ray Pulsars). It has defied any physical explanation since it was discovered in 1982 .
Data on its characteristics were provided by NASA’s Rossi X-ray Timing Explorer observatory. The discovery was carried out by a team led by Victoria Kaspi, from Canadian McGill University.
AXPs have been suspected of being magnetars for years, but the definitive proof was lacking. Now, the Rossi satellite has surprised one of them in full explosion, as a magnetar would.
A neutron star is an ultra-dense sphere about 16 km in diameter. It is the core of a collapsed star that was one day ten times more massive than the Sun and exploded in the form of a supernova. Those that emit continuous pulses of X radiation when they rotate are known as X-ray pulsars.
The AXPs have been classified as anomalous as scientists had not been able to determine their power source. Other types of neutron stars glow due to rotational or gravitational energy, but this is not the case for AXPs, almost undetectable in any region of the electromagnetic spectrum other than X-rays.
According to Rossi’s observations, the X-ray source for AXPs lies in their magnetic energy. Since 1979 some have been known to possess very high magnetic fields, which are reflected in large bursts of gamma rays or X-rays. Their intensity is a thousand times greater than that of ordinary neutron stars. Only five objects (magnetars) of this type were known.
Nor was it known that AXPs could also suffer such outbursts. In fact, they may be younger versions of a phenomenon.
Stellar corpses
Magnetars are stellar corpses that have an extremely strong magnetic field and are part of a new class of astronomical objects, which were discovered a few years ago. The magnetic field is about 1 billion times stronger than Earth’s. Magnetars are part of neutron stars, which are the stellar remnants of a giant star. However, regarding its creation there is still no generally accepted theory.
Life of a star
The astronomers led by Ritchie wanted to determine how massive a star really has to be to become a black hole and how massive the precursor star of the magnetar cluster Westerlund 1 was.
Because the giant stars in the stellar supercluster all formed at the same time, the magnetar’s precursor must have possessed more mass than the stars still shining there.
Since the lifetime of a star is directly related to its mass, the more massive a star is, the shorter its life will be – if we can measure the mass of any surviving star we will know for sure that the shortest-lived star that is turned into the magnetar it must have been even more massive. […] This is of great importance as there is no accepted theory about how these extremely magnetic objects were formed.
Simon Clark, leader of the team of astronomers, according to an ESO statement
Magnetars puzzles astronomers and casts doubt on the current theory of black hole formation , since it is assumed that from the death of a very large star a black hole is generated and not a magnetar.
Unknowns pending
Astronomers estimate that the precursors have a mass between 35 and 40 times greater than our Sun to which the Earth belongs. According to current theory, stars that have a mass equivalent to 25 solar masses should end their existence by collapsing into a black hole.
The magnetar’s precursor should somehow lose about 90 percent of its mass before exploding as a supernova. This is very difficult to explain with current models of stellar development.
Therefore, the difficult question is asked of how much mass a star must have to finally collapse into a black hole, when this is not achieved by stars with more than 40 solar masses.
Norbert Langer, an astronomer at the University of Bonn ( Germany ).
