CEA News, October 2018

A fixed Hubble captures a rare lensed galaxy for Durham astronomers

After three weeks out of operation with a faulty gyroscope, the Hubble Space Telescope returned to work on Saturday 27th October, and Durham astronomers were among the first to benefit. The image shown here was obtained for Dr Russell Smith of the Centre for Extragalactic Astronomy (CEA), just hours after full science operations resumed.

The galaxy at the centre of the picture is a gravitational lens system, in which the light from a background galaxy is split and distorted by the curvature of space-time around a giant elliptical galaxy in the foreground. This extremely rare alignment was discovered by CEA student Will Collier earlier this year as part of his PhD research project (see Collier et al. 18).

The Hubble image reveals a wealth of new detail in this system, and will be used to `weigh' the stars in the elliptical galaxy, by measuring the lensing distortions with more accuracy than previously possible. The results will help to test whether all galaxies were built from a similar mix of low- and high-mass stars, or if the mix varies with local conditions at the epoch of galaxy formation, which is an area of ongoing research at the CEA.