This time-lapse movie, made from eight Hubble Space Telescope images, shows the apparent motion of the white dwarf star Stein 2051 B as it passes in front of a distant star.
The observations were taken between Oct. 1, 2013, and Oct. 14, 2015.
White dwarfs are the burned-out remnants of normal stars. When the white dwarf passed in front of the faraway star, its gravity deflected the starlight, which appeared offset by about 2 milliarcseconds from its actual position. This deviation is so small that it is equivalent to observing an ant crawl across the surface of a quarter from 1,500 miles away. From this measurement, astronomers calculated that the white dwarf's mass is roughly 68 percent of the sun's mass.
Stein 2051 B is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein. It resides 17 light-years from Earth. The background star is about 5,000 light-years away.
Publication: June 7, 2017