by Kathleen Riley February 6, 2017 Space
In Brief
  • Astronomers are finding strange new additions to the universe all the time—one of the most recent is an extremely rare type of neutron star/normal star setup called the "Rapid Burster."
  • The new discovery will allow astronomers and physicists to study the behavior of some of the densest objects and most powerful magnetic fields in the universe.

Strange Bursts

It should come as no surprise that there are some pretty remarkable things happening in our universe, and a fairly recent discovery does not disappoint.  It’s a cosmic oddity that illustrates Hamlet’s oft-quoted observation: “There are more things in heaven and earth, Horatio / Than are dreamt of in your philosophy.”

In this case, scientists noticed that a star system was emitting “sudden, erratic, and extremely intense” X-ray bursts, so they sought to investigate the matter. They took three space telescopes and set their eyes on a binary system dubbed “Rapid Burster,” first discovered in the 1970s.

Rapid Burster contains a neutron star—the incredibly dense stellar core left in the wake of the supernova death of a massive star—and smaller star akin to the Sun. Together, the setup was thought to have produced “Type-I” X-ray bursts. This occurs when the dense neutron star strips the gas off its companion star, cannibal fashion. But what the scientists next found was that Rapid Burster also exhibited “Type-II” bursts, an extremely rare occurrence. It’s so rare, in fact, that only one other system in the universe was found to show Type-II bursts.

Illustration of the stages in "Rapid Burster's" life. At first, the neutron star's intense magnetic field keeps the infalling stellar material at bay (1); over time, the material increases in density and velocity at the inner edge of the accretion disc (2-3), until it finally overwhelms the staying power of the field and crashed catastrophically onto the neutron star's surface (4). Credit: ESA/ATG medialab
Illustration of the stages in “Rapid Burster’s” life. At first, the neutron star’s intense magnetic field keeps the infalling stellar material at bay (1); over time, the material increases in density and velocity at the inner edge of the accretion disc (2-3), until it finally overwhelms the staying power of the field and crashed catastrophically onto the neutron star’s surface (4). Credit: ESA/ATG medialab

A Reluctant Glutton

Scientists believe that the neutron star’s incredibly powerful magnetic field is the cause for these erratic bursts—truth is, the astonishing magnetic fields of neutron stars are implicated in a number of cosmic phenomena. In the present case, the neutron star’s magnetic field is spinning so fast it creates an inner edge to the companion star’s gaseous disc—essentially, the star’s intense magnetism acts as a force field preventing the gaseous material from falling onto the stellar remnant’s surface.

Gradually, the amount of material on the accretion disc’s inner edge accumulates into a great torus; finally, it achieves such an energy quotient that it overwhelms the power of the magnetic field, and crashes onto the neutron star’s surface all at once, triggering an explosive outburst of X-rays.

The video below shows an animation of this occurrence:

With continued research, and the ever-increasing resolving power of ground- and space-based telescopes and instruments, we will be able to gain a greater understanding of neutron stars and their magnetic fields—which constitute some of the most powerful destructive, and creative, forces in the universe.

Rapid Burster is helping to pioneer this research, as it is the only source ever discovered to display both Type-I and Type-II X-ray bursts. Further study of this remarkable object, and others like it, will help us understand not only the nature of neutron stars—which are even, incredibly, capable of creating and hosting planetary systems—but also the behavior of matter and physics at extremes impossible to probe in the homely confines of our sedate little planet.