Imagine that the size of a bacterium is measured at a distance of about 4500 light-years. This would be an unusual measurement, considering that a bacterium is so small that a microscope is needed to see it, and what an enormous distance light can travel in 4500 years, given that it can travel the earth more than seven times in mere one second. But a small deformation of the size of a bacterium, which is an extra height of a few micrometers in one direction, is now for a neutron star at a distance of about 4500 light-years, from a study of prof. Sudip Bhattacharyya of the Tata Institute of Fundamental Research (TIFR), India. This study is published in a new paper in Monthly announcements from the Royal Astronomical Society.
A microscopic deformation of the neutron star in the binary stellar system PSR J1023 + 0038 is derived. Here the spin axis of the star is perpendicular to the planet of the figure. The extra height of the neutron star in one direction is only a few micrometers that is the size of a bacterium, which is estimated at a distance of about 4500 light-years. Credit: Sudip Bhattacharyya
Neutron stars are incredibly dense cosmic objects. They are about the size of a city, but contain more material than in the Sun, and a handful of stellar things would make a mountain on Earth heavier. Some of them are observed spinning several hundred times in a second, and we call them millisecond pulsars. A slight asymmetry or deformation over the spinas of such a star would cause the emission of gravitational waves non stop.
Gravitational waves, which ripple in space-time, have recently provided a new window to the universe. But so far they have been found as transient phenomena of fusions of black holes and neutron stars. Persistent gravitational waves, for example from a slightly deformed and rotating neutron star, have not been discovered so far. Current instruments may not have the capacity to detect these waves if the deformation is too small.
One way to indirectly conclude such waves and measure this deformation is to determine the contribution of the waves to the spin-down rate of the waves. pulsar, that was not possible until now. PSR J1023 + 0038 is a unique cosmic source for this purpose because it is the only millisecond pulsar for which two spin-down rates, in the phase of mass transmission of the companion star and in the phase as d ‘ r is not mass transfer, were measured. By using these values, and in the first place a fundamental principle of physics, that is the conservation of angular momentum, Bhattacharyya has delivered continuous gravitational waves and has estimated the microscopic deformation of the neutron star.
Reference: “The permanent ellipticity of the neutron star in PSR J1023 + 0038” by Sudip Bhattacharyya, 18 August 2020, Monthly announcements from the Royal Astronomical Society.
DOI: 10.1093 / mnras / staa2304
