SCIENTISTS have calculated the mass of a star using the gravity of a celestial body hanging in space outside the solar system for the first time.
A team at the university of University of St Andrews made the breakthrough by using analysing the way light 'bends' when encountering gravity created by a massive object in space.
The phenomenon behind the technique, called astrometric microlensing, was predicted by Einstein's Theory of General Relativity and involves the warping of space-time by massive bodies.
In 1919, scientist Arthur Eddington’s observations during a solar eclipse of the displacement of stars caused by the bending of their light by the Sun was the first time the theory was put into practice.
This time astronomers were able to precisely determine the mass of the white dwarf star Stein 2051 B by repeatedly observing the changing position of another closely aligned star passing in the background over two years.
Like invisible glass lenses affecting light, the gravitational field of stars displaces and distorts the images of background stars passing in angular proximity on the sky, providing a direct measurement of the mass of the foreground star.
Dr Martin Dominik, of the School of Physics and Astronomy at the University of St Andrews, who co-authored the new study said:
“While Eddington measured an already incredibly small angle corresponding to the diameter of a human hair seen from 10m distance, we measured displacements that were 1000 times smaller, corresponding to the angle subtended by a virus at the same distance.”
The study’s lead researcher Dr Kailash Sahu from the Space Telescope Science Institute (STScI) in Baltimore said: “It’s like placing the star on a scale: the deflection is analogous to the movement of the needle on the scale.”
The results of the study will be reported in the renowned journal Science this week.
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