Astronomers have measured the mass of a lone white dwarf star for the first time.
When the sun dies in around 5 billion years it will leave behind this type of smoldering stellar remnant.
Hubble Space Telescope measured the mass of a white dwarf designated LAWD 37, which burned out over 1 billion years ago.
The team determined that LAWD 37 has a mass of around 56% that of the sun.
This particular white dwarf is well studied because it is relatively close to Earth at just 15 light-years away in the constellation of Musca.
In pairs, astronomers can get a mass measurement by applying Newton's theory of gravity to the motion of two stars orbiting each other.
Scientists used a phenomenon first predicted in 1915 by Albert Einstein called "gravitational lensing," which involves the bending of light by objects of great mass.
To measure the mass of this singleton star, the researchers turned to Einstein's formulation of gravity, his theory of general relativity.
LAWD 37 acted as a foreground gravitational lens, slightly deflecting the light traveling past it from a background star and offsetting its position in the sky.
Researchers had used a similar process to find the mass of another white dwarf in 2017, but that was not a solo dead star like LAWD 37