Hubble Measures Deflection of Starlight by a Foreground Object

Hubble Measures Deflection of Starlight by a Foreground Object

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Fast Facts
News release ID: STScI-2017-25
Release Date: Jun 7, 2017
Image Use: Copyright
About this image

How Gravity Can Bend Starlight

This illustration reveals how the gravity of a white dwarf star warps space and bends the light of a distant star behind it.

White dwarfs are the burned-out remnants of normal stars. The Hubble Space Telescope captured images of the dead star, called Stein 2051 B, as it passed in front of a background star. During the close alignment, Stein 2051 B 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 resides 17 light-years from Earth. The background star is about 5,000 light-years away. The white dwarf is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein.

American Astronomical Society Meeting, Annotated Observations, Artwork, Gravitational Lensing, Hubble Telescope, Stars, White Dwarfs


NASA, ESA, and A. Feild (STScI)