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University of Sussex physicists help discover new stellar streams

Professor Kathy Romer at the telescope in Chile

Scientists from the University of Sussex, headed up by Professor of Astrophysics, Kathy Romer, are part of a team of 100 physicists from around the world who journeyed to Chile to study ‘dark energy’.

This week, Professor Romer and her colleagues have released the first three years’ of data from the Dark Energy Survey, announced at the American Astronomical Society meeting in Washington, DC on Wednesday 10 January. This first major release of data from the survey includes information on around 400 million astronomical objects, including distant galaxies billions of light years away as well as stars in our own galaxy.

Scientists from the Dark Energy Survey are using this data to learn more about dark energy, the mysterious force believed to be accelerating the expansion of the universe. One of the key cosmological findings is the discovery of 11 new stellar streams, which are ribbons of stars orbiting a galaxy.

Professor Romer came up with the idea of asking Chilean schoolchildren to name some of the stellar streams. She says:

"I am really proud of the part that the University of Sussex has played in making the first Dark Energy Survey data release possible.

“As a team, the Sussex scientists clocked up over 100 nights at the mountain in Chile. We played an essential role in checking the quality of the data. Other than myself and a former postdoctoral fellow, Dr Marisa March, these contributions have all been thanks to our wonderful PhD and undergraduate students.

“One thing that I am especially delighted about is that my idea of asking Chilean school children to name the stellar streams was taken on. Two high school students from Vicuna, the town nearest to the telescope, researched words from the native Quechua and Aymara cultures that were related to water. They then presented several options to about 90 kindergarten and first-grade students, who made the final choices. Their selections were the Aymara name Aliqa Una, meaning Quiet Water, and two Quechua names, Palca, meaning Crossing Rivers, and Willka Yaku, or Sacred Water.”

Jessica May Hislop, a final-year undergraduate student who works with Professor Romer on the Dark Energy Survey, says:

“Releasing the data to the public is very exciting. There’s a lot of weight on our shoulders to make sure the hard work from the whole of the Dark Energy Survey collaboration is shouted from the rooftops to the science community and the public.

“I’m so proud of what we’ve achieved and very honoured have been awarded co-authorship on the scientific paper. I am so grateful for these opportunities available to me as an undergraduate at the University of Sussex.”

Stellar streams are remnants of smaller galaxies torn apart and devoured by our Milky Way. Stellar streams provide insight into the formation and structure of the Milky Way and its dark matter halo and give a snapshot of a larger galaxy being built out of smaller ones. Prior to the survey, only around two dozen stellar streams had ever been discovered.


By: Anna Ford
Last updated: Friday, 12 January 2018