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Curated by RSF Research Staff

Weighing a Star with Light

Stellar mass along with other parameters such as radius, temperature and luminosity allow scientists to infer the nature and evolution of a particular star. This information is then fed into the overall story of stellar formation, growth and evolution. Obtaining accurate measurements is therefore of paramount importance to the development of stellar theory.

Binary stars are the perfect objects for measuring the mass of its stellar components, where from the variable light of the stellar system astrophysicists are able to observe the orbital dynamics and determine a mass to within 10% certainty. However, the accuracy depends on the type of star and numerous other factors such as the level of interaction between the two stars. Such factors can complicate matters and hugely effect the degree of accuracy to which the mass is determined.

That is where Einstein comes to the rescue and the technique of gravitational microlensing which allows the mass of a foreground ‘lensing’ star to be determined to an amazingly high degree of accuracy. This techniques measures how much the light of a background star is deflected by the ‘lensing’ star that passes in front. Another brilliant fact about this technique is that the background star does not need to be bright as the lensing star deflects the light of even the faintest of stars.

Utilizing the Hubble Space Telescope, a team of astronomers have been able to use this technique to measure the amount of light, from a background star, that is deflected by the ‘lensing’ white dwarf star Stein 2051 B. This allowed them to determine a mass for the white dwarf star to a much greater degree of accuracy and precision than measurements found from the techniques typically utilized for binary systems.

Improved mass determination techniques like this, not only have huge implications for furthering our understanding of stellar evolution, but as well on the physics of high density stars such as white dwarfs and the verification of unified physics theories.


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