>> highly magnetized rotating neutron stars formed from the remains of massive stars after they explode into supernovae. Until now, scientists have determined the mass of stars, planets and moons by studying their motion in relation to others nearby, using the gravitational pull between the two as the basis for their calculations. However, in the case of young pulsars, mathematicians have now found a new way to measure their mass, even if a star exists on its own in space.
Until now, scientists have determined the mass of stars, planets and moons by studying their motion in relation to others nearby, using gravitational pull between the 2 as the basis for calculations. However, “For pulsars, we have been able to use principles of nuclear physics, rather than gravity, to work out what their mass is – an exciting breakthrough which has the potential to revolutionise the way we make this kind of calculation,” said Dr Wynn Ho.
“All 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 or Moon, or discover the first extrasolar planets. Our technique is very different and can be used for pulsars in isolation.” They are renowned for their incredibly stable rate of rotation, but young pulsars occasionally experience so-called ‘glitches’, where they are found to speed up for a very brief period of time. The theory is they arise as a rapidly spinning superfluid within the star transfers its rotational energy to the star’s crust, the component that is tracked by observations.
New radio and X-ray data were used to develop a novel mathematical model that can be used to measure the mass of pulsars that glitch. The idea relies on superfluidity. 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. By combining observational information with the involved nuclear physics, one can determine the mass of the star.
The team’s results have important implications for the next generation of radio telescopes being developed by large international collaborations, like the Square Kilometre Array (SKA) and the Low Frequency Array (LOFAR).
“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,” says Professor Andersson. http://www.alphagalileo.org/ViewItem.aspx?ItemId=157008&CultureCode=en
An artist’s impression of a pulsar with its surrounding magnetic fields (blue lines). Image credit – Russell Kightley Read more at: http://phys.org/news/2015-10-star.html#jCp
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