- 3077 - MAGNETARS - and Gamma Ray Burster stars? Magnetars could be the natural end product of [main-sequence] and probably also pre-[main-sequence] mergers. Astronomers may finally understand the origin of magnetars and their strong magnetic fields.
--------------- 3077 - MAGNETARS - and Gamma Ray Burster stars
- Our Sun is an ordinary star. Smaller stars live a long time. Our star should live for 10 billion years. It is at mid-life right now. Bigger stars are shirt lived and have fast and unusual deaths. One is called a Magnetar and another is a Gamma Ray Burster.
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- Throughout the universe these gamma-ray bursters create bright explosions that blast through space. These gamma-ray bursts are the brightest explosions known. A typical gamma-ray burst can produce as much energy in the seconds of its explosion than the sun produces in its entire lifetime.
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- Despite their intensity, scientists still don't know exactly what causes “gamma ray bursts“.
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- Long-duration gamma-ray bursts, come from very massive, fast-spinning stars. Stars like these in a binary system, in orbit with a companion star, are most likely what produce the most massive explosions.
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- It’s unlikely many single massive stars that start off spinning fast would stay that way at the ends of their lives. Massive stars tend to blow off a lot of material over time, which slows their spinning, like ice skaters throwing out their arms mid-spin.
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- That means it would be difficult to explain why all the long-duration gamma-ray bursts astronomers see, roughly one per day, occur with single stars. But if a massive, fast-spinning star had a companion, gravitational interactions within this binary system might be able to keep the star spinning fast and producing these powerful bursts.
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- Systems with stars that spun fast enough to create such energetic explosions are probably common enough that binary star systems could account for all the long-duration gamma-ray explosions astronomers are seeing.
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- More than 60 years ago, astronomers realized about 10 percent of massive stars have powerful magnetic fields bursting from their surfaces. But the exact origins of these magnetic fields, which can reach hundreds to thousands of times the strength of the Sun's, has so far remained a mystery.
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- The answer may be due to a collision between two normal stars. To learn more scientists recently used cutting-edge simulations to uncover an evolutionary path they think explains the formation of extremely magnetic stars. (March, 2021).
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- Their findings may also shed light on the origins of other astronomical oddities. These mysteries include “magnetars” (a rare type of hyper-magnetic neutron star), “blue stragglers” (massive stars that appear too young for their age), and maybe even cosmic events like “fast radio bursts” and ‘super-luminous supernovae“.
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- When two stars collide, it sends their surfaces spinning and simultaneously kicks off enormous amounts of turbulence. This dramatically boosts the final star’s magnetic field. As the star spins, its inner layers rotate faster than its outer layers, called differential rotation.
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- Running through and connecting each of these layers are magnetic field lines. Because each layer rotates at a different speed, the magnetic field lines connecting the layers get twisted and tangled up. This serves to amplify the overall strength of the magnetic field.
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- During a merger event, stellar material gets violently sloshed around. This turbulence further stirs the magnetic field lines, exponentially increasing the star's magnetism.
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- Blue stragglers are a unique class of stars that masquerade as stars younger than they truly are. These "rejuvenated" stars are much hotter, making them bluer, and brighter than your average main-sequence star of a similar apparent age.
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- Typical main-sequence stars power themselves by fusing hydrogen into helium in their cores. But when the hydrogen in their cores runs out, they move on to fusing concentric shells of hydrogen around their now-inert cores. This causes the star to balloon up into a red giant, moving it off the main-sequence and into the red giant branch.
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- But if two main-sequence stars collide, their material gets mixed together. The resulting merged product now has a restocked reservoir of hydrogen in its core, which allows it to chug along as a more massive, yet still main-sequence, “blue straggler” instead of evolving into a “red giant“ star.
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- This only makes the newly formed star appear younger. The simply that the blue straggler could have lived for a long time as lower-mass stars and then merged to become this more massive blue straggler.
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- Scientists first suggested a collision between two stars could generate strong magnetic fields more than a decade ago. This can explain the properties of the magnetic 'blue straggler' stars
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- Such massive blue straggler stars may also be the progenitors of magnetars, perhaps giving rise to some of the enigmatic fast radio bursts observed, and their supernovae may be affected by their strong magnetic fields.
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- Magnetars are a rare breed of neutron stars with absurdly powerful magnetic fields that reach some 5 quadrillion (one quadrillion is 1,000 trillions) times stronger than Earth's.
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- Magnetars could be the natural end product of [main-sequence] and probably also pre-[main-sequence] mergers. Astronomers may finally understand the origin of magnetars and their strong magnetic fields.
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March 5, 2021 MAGNETARS - and Gamma Ray Bursters? 3077
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