Heriot-Watt University is helping the Southern African Large Telescope (SALT) embark on finding new planets outside of our solar system.

The SALT team has installed a Heriot-Watt-designed laser frequency comb (LFC), also known as an astrocomb.

The astrocomb will help astronomers explore distant planetary systems by complementing SALT’s high-resolution spectrograph, which was designed with such research in mind.

A state-of-the-art ‘ruler’ to measure starlight 

Laser experts from Heriot-Watt University designed the bespoke astrocomb for SALT. It enables SALT’s high-resolution spectrograph to detect minute velocity variations in starlight.

Dr Richard McCracken from Heriot-Watt University led the design of the astrocomb. He said: “The astrocomb will allow the telescope’s spectrograph to detect variations in incoming starlight.

“Variations can be caused by the wobble that can be introduced by one or more planets outside our solar system, or exoplanets, orbiting a star.

“The astrocomb acts like an incredibly finely-graduated ruler that can measure the wobbles and any variations of light from these stars.

“The new astrocomb will give astronomers and researchers the certainty that they can precisely detect and measure these variations in starlight.”

A leap for astronomical technologies

The Heriot-Watt and SALT teams have been working on the astrocomb since 2015.

The SALT team’s experience with an experimental version of the astrocomb in 2016 spurred enhancements in design, propelling HWU to the forefront of astrocomb technology development.

Funded by the National Research Foundation in South Africa, this initiative underscores a commitment to advancing astronomical capabilities.

Dr Lisa Crause, SALT Observatory Scientist said: “The astrocomb is an incredibly exciting addition to our instrument suite, with huge implications for the high-resolution spectrograph and SALT’s precision radial velocity capabilities, including hunting for exoplanets.

“But even more significant is the fact that SALT is participating in the incubation of critical technologies needed to help advance this challenging field.

“It’s an absolute treat for observatory staff to get to work with and learn from laser physicists about fascinating equipment that we’d ordinarily have no business playing with.

“Having the new astrocomb permanently in place at SALT means we’ll be able to continuously upgrade and improve the comb, adapting it to incorporate cutting-edge technologies. It’s a very exciting prospect.”

The astrocomb is undergoing testing at SALT and will be released to SALT’s user community in 2025.

Heriot-Watt scientists have also contributed to astrocomb design for the Extremely Large Telescope in Chile.

The university recently had its plans approved for a £ 2.5 million telescope station at its research park in Edinburgh. The Hub Optical Ground Station will demonstrate and test satellite quantum secure communications to counter cyberattacks.

The optical ground station will also support research across a range of areas including space situational awareness, astronomy, astrophotonics, and optical communications.