Discusión:Magnétar

The Life of a Magnetar

When in a supernova a star collapses to a neutron star, its magnetic field increases dramatically in strength. Duncan and Thompson calculated that the magnetic field of a neutron star, normally an already enormous 10⁸ teslas could under certain circumstances grow even larger, to more than 10¹¹ teslas.^[1] Such a highly magnetic neutron star is called a magnetar.

In the outer layers of a magnetar, which consist of a plasma of heavy elements (mostly iron), tensions can arise that leads to 'starquakes'. These seismic vibrations are extremely energetic, and result in a burst of X-ray and gamma ray radiation. To astronomers, such an object is known as a soft gamma repeater.

It is estimated that about 1 in 10 supernova explosions results in a magnetar rather than a more standard neutron star or pulsar. This happens when the star already has a fast rotation and strong magnetic field before the supernova. It is thought that a magnetar's magnetic field is created as a result of a convection-driven dynamo of hot nuclear matter in the neutron star's interior that operates in the first ten seconds or so of a neutron star's life. If the neutron star is initially rotating as fast as the period of convection, about ten milliseconds, then the convection currents are able to operate globally and transfer a significant amount of their kinetic energy into magnetic field strength. In slower-rotating neutron stars, the convection currents only form in local regions.

The life of a magnetar as a soft gamma repeater is short: The energy release of explosisions (starquakes) slows the rotation (causing magnetars to rotate much more slowly than other neutron stars of a similar age) and weakens the magnetic field, and after only about 10,000 years the starquakes cease. After this, the star still radiates X-rays, forming an object known to astronomers as an anomalous X-ray pulsar. After another 10,000 years, it becomes completely quiet. These are blockbuster detonations and some have been directly recorded, such as that at SGR 1806-20 on December 27, 2004, and more are expected to be recorded as telescopes increase in fidelity.

As of December 2004, 4 soft gamma repeaters and 5 anomalous X-ray pulsars are known, with a further four candidates in need of confirmation.

Reference

↑ Origin of magnetars - CNN February 2, 2005. A magnetic field above 10 gigateslas is strong enough to wipe a credit card from half the distance of the Moon from the Earth. A small neodymium based rare earth magnet has a field of about a tesla, Earth has a geomagnetic field of 30-60 microteslas, and most media used for data storage can be erased with a millitesla field.

Masa del magnetar

En el artículo en inglés dice:

"Like other neutron stars, magnetars are around 20 kilometres (12 mi) in diameter and have a mass 2–3 times that of the Sun. The density of the interior of a magnetar is such that a thimble full of its substance would have a mass of over 100 million tons."

Pero en español dice:

"(Aun así, la masa del Sol es unas 50 000 veces mayor que la del magnetar mencionado)"

Tiene más sentido que diga que el magnetar tiene más masa que el sol.

[1] Origin of magnetars - CNN February 2, 2005. A magnetic field above 10 gigateslas is strong enough to wipe a credit card from half the distance of the Moon from the Earth. A small neodymium based rare earth magnet has a field of about a tesla, Earth has a geomagnetic field of 30-60 microteslas, and most media used for data storage can be erased with a millitesla field.

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