New Technique to Weigh a Star: Pulsars Get on a Scale

First Posted: Oct 05, 2015 11:12 AM EDT

There may be a new way to weigh a star. Scientists have developed a new method for measuring the mass of pulsars, which are highly magnetized rotating neutron stars that are formed from the remains of massive stars after they explode into supernovae.

In the past, researchers 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, researchers have found a new way to measure their mass.

"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," said Cristobal Espinoza, one of the researchers, in a news release. "Our technique is very different and can be used for pulsars in isolation."

Pulsars actually emit a rotating beam of electromagnetic radiation, which can be detected by telescopes when the beam sweeps past Earth, rather like observing the beam of a lighthouse. These beams are renowned for their incredibly stable rate of rotation. Young pulsars, though, occasionally experience so-called "glitches," where they are found to speed up for a very brief period of time.

"Imagine the pulsar as a bowl of soup, with the bowl spinning at one speed and the soup spinning faster," said Nils Andersson, one of the researchers. "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."

In this latest study, the researchers developed a novel mathematical model that can be used to measure the mass of pulsars that glitch. The idea relies on a detailed understanding of superfluidity. By combining observations with the physics of it, researchers can determine the mass of the star.

The findings are published in the journal Science Advances.

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TagsPulsar, star, Stars, Physics, space, Weight, astronomy