A measurement that has been calculated from the gravitational deviation of the light emitted by another star . Thanks to this experiment, it has been possible to know that the star in question, a white dwarf , has approximately 68% of the mass of the Sun.
The research has been carried out thanks to a type of gravitational microlensing that has confirmed one of Einstein’s predictions and that sheds light on understanding the history and evolution of galaxies like ours . Back in 1919, the deflection or gravitational deflection of the starlight that passed around the Sun during the solar eclipse that took place that year provided a series of data that agreed with Einstein’s theory of general relativity . The great German physicist predicted that whenever light from a distant star passes a closer object, gravity acts as a kind of magnifying glass , illuminating and magnifying the luminosity of distant stars.
However, in an article published in 1936 in the journal Science , Einstein added that because the stars are so far apart, “there is not much hope or possibility of directly observing this phenomenon.” And it is that one of the key predictions of his general relativity established that the curvature of space near huge bodies, such as stars, causes any ray of light that passes near them to deviate twice as much as would be expected depending on traditional gravity laws. The father of relativity predicted that when a front star comes between us and another star in the background, a phenomenon called gravitational microlensing occurs that generates a perfect ring of light, also called the ‘Einstein ring’ .
But now, an international research team led by Kailash C. Sahu, with astronomers from the Space Telescope Science Institute in Baltimore, has succeeded in doing what Einstein believed impossible . One hundred years after Einstein developed the theory of general relativity, which has revolutionized the way we humans understand the universe , a group of researchers at the Space Telescope Science Institute (USA) has succeeded in determining mass. of a white dwarf star from Einstein’s laws. The research has been published in Science . Oswalt, an astronomer and chair of the Department of Physical Sciences at the Embry-Riddle University campus in Daytona Beach, Florida, says “Einstein would be proud, one of his key predictions has passed the test rigorously.”
The reality is that, after a century of technological advances, it had not been possible to observe two slightly misaligned stars that generate an asymmetric Einstein ring . According to Einstein, this asymmetry is important because it would cause the background star to deviate from the center, and it could be used to determine the mass of another frontal star located ahead. Scientists coordinated by Kailash Chandra Sahu from the Space Telescope Science Institute looked for this rare asymmetric alignment in more than 5,000 stars. Finally, in March 2014 they discovered that the white dwarf star Stein 2051 B was in the perfect position, right in front of a background star .
So, they pointed the Hubble Space Telescope at the phenomenon and measured the small changes in the apparent position of the background star over time. From the information collected, they have been able to estimate that the mass of the white dwarf was equivalent to approximately 68% of that of our Sun.
The direct measurement of the mass of Stein 2051 B also offers important data to better understand the evolution of white dwarfs, the most common type of stars in the universe . In fact, most of the stars that have formed in our galaxy, including the Sun, will become or are already white dwarfs.
