Mathematicians weigh in on stellar mass
4 Nov 2015 by hjqbcptqcm.d hjqbcptqcm.d
Mathematicians have developed a new method for measuring the mass of pulsars.
Scientists at the University of Southampton used nuclear physics principles, rather than gravitational pulls between stars and planets, to work out the mass of pulsars – highly magnetised rotating neutron stars formed after the explosion of supernovae.
Professor of Applied Mathematics at Southampton, Nils Andersson said: “Our results provide an exciting new link between the study of distant astronomical objects and laboratory work in both high-energy and low-temperature physics. It is a great example of interdisciplinary science.”
Pulsars emit a rotating beam of electromagnetic radiation, detected by telescopes when the beam sweeps past the Earth, and are known for their incredibly stable rate of rotation. However, young pulsars occasionally experience what scientists call glitches, where they are found to speed up for a very brief period of time. These glitches are thought to arise as rapidly spinning superfluid within the star transfers its rotational energy to the star’s crust, the component that is tracked by observations.
“Imagine the pulsar as a bowl of soup, with the bowl spinning at one speed and the soup spinning faster. Friction between the inside of the bowl and its contents, the soup, will cause the bowl to speed up. The more soup there is, the faster the bowl will be made to rotate,” said Professor Andersson.
Previous precise measurements of pulsar masses have been made for stars that orbit another object, using the same techniques that were used to measure the mass of the Earth and Moon, or discover the first extrasolar planets.
In the study, published in the journal Science Advances, the team combined radio and X-ray data to develop the mathematical model that can measure the mass of pulsars that glitch. By testing theoretical superfluid models against the most recent glitch data, they created a model that relies on the superfluidity where the magnitude and frequency of the pulsar glitches depend on the amount of superfluid in the star and the mobility of the superfluid vortices within. This technique will allow astronomers to measure the mass of pulsars in isolation.
The scientists believe these findings might have important implications for the next generation of radio telescopes such as the Square Kilometre Array and the Low Frequency Array.
