Source of fast radio bursts may be dying planets near neutron stars

(ORDO NEWS) — Mysterious radio bursts – incredibly powerful and short signals – can create fragments of planets that neutron stars tear off from them, showering them with their hard radiation.

In 2007, astronomers first noticed a strange signal – a brief, but extremely powerful burst in the radio range. Its unknown, compact and distant source radiated as much energy in a few milliseconds as the Sun loses in a few days.

Since then, almost a hundred such fast radio bursts (Fast Radio Bursts, FRB) have been registered, but their nature is still a mystery.

Most likely, they are associated with superdense neutron stars or with magnetars – neutron stars with a huge magnetic field.

However, there are other versions that connect the FRB with hypothetical quark stars, and even with the communications of extraterrestrial civilizations. In an article published in The Astrophysical Journal, Chinese astrophysicists put forward a new idea: fast radio bursts can create planets that die when they get too close to neutron stars.

Planets can indeed exist near such extreme objects. Yong-Feng Huang of Nanjing University and his colleagues have simulated a system consisting of a neutron star and a planet orbiting in a tight and highly elongated orbit.

Either approaching a star, or moving away from it, such a planet experiences a powerful action of tidal forces in its inhomogeneous gravitational field. Thanks to these forces, the star “bites off” piece by piece from the planet.

Relatively small – no more than a few kilometers – fragments break off from it, which can create radio bursts. A neutron star emits a stellar wind much stronger than a typical average star like the Sun.

Under the influence of this flow of particles and radiation, a cloud of fragments of a dying planet can radiate brightly in the radio range. And when such debris flies between a neutron star and us, observing it from Earth, the instruments record this radiation as a fast radio burst.

Based on data from two previously recorded bursts – FRB 121102 and FRB 180916 – scientists have shown that such a scenario can explain both their periodicity (157 and 16.4 days, respectively) and brightness. And new long-term observations of such repetitive radio bursts will help confirm or refute the hypothesis.

If they are really created by planets around neutron stars, the orbits of such planets should degrade rather quickly. Changes in the orbit should affect the nature of the next bursts, which can be seen on a scale of several years.

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