Milky Way was part of cosmic collision 10 billion years ago

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CBC News

Un impact vieux de dix milliards d'années a façonné la Voie lactée

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'Messenger' star formed right after Big Bang discovered by UVic researcher

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Journey to the Beginning of Time

October 10, 2018

In the “Pristine” survey, an international team is looking for and researching the oldest stars in our universe.  The goal is to learn more about the young universe right after the Big Bang. This team is co-led by former UVic postdoctoral fellow Dr. Else Starkenburg (now at the Leibniz Institute for Astrophysics Potsdam, AIP, Germany).  Local scientists on this team include UVic professors Kim Venn and Julio Navarro, graduate student Collin Kielty, former undergraduate student Kris Youakim (now a graduate student at AIP, Germany), and adjunct professors from the NRC-Herzberg, Patrick Cote and Alan McConnachie.

In a recent publication, the scientists report on the discovery of a particularly metal-poor star: a messenger from the distant past. For the study of the early universe astronomers have different methods at their disposal: One is to look far into the Universe and back in time, to see the first stars and galaxies growing.  Another option is to examine the oldest surviving stars in our home galaxy, the Milky Way, for information from the early Universe.

The Pristine survey is looking for exactly these pristine stars. The scientists employ a special colour filter on the Canada-France-Hawaii Telescope in Hawaii to search for stars with relatively pristine atmospheres. In their recent publication (Starkenburg et al., 2018) they have used this technique to discover one of the most metal-poor stars known.

Detailed follow-up studies with spectrographs of the Isaac Newton Group in Spain and the European Southern Observatory in Chile have demonstrated that the star has indeed very few heavy elements in its atmosphere. Most elements are depleted by factors 10,000 to 100,000 compared to the Sun.  Additionally, its detailed pattern of different elements stands out.  Whereas most heavy element depleted stars do show a large enhancement in carbon, this star does not.  “This makes this star the second of its kind and an important messenger from the early Universe.“ says Dr. Else Starkenburg.

 To find these oldest messengers among the overwhelming population of younger stars is no easy task. Just after the Big Bang, the Universe was filled with hydrogen and helium and a bit of lithium. No heavier elements were around, as these are only synthesized in the hot interior of stars - and those did not exist yet. Our Sun has about 2% of heavier elements in its atmosphere, as can be seen when we make a spectrum of its light. Because of this fact, astrophysicists can conclude that the Sun has emerged as part of a later generation of stars - and “recycled” in its atmosphere  with the products of stars that lived before it and have since died out.

In searching for the oldest stars, scientists look for stars with more pristine atmospheres than our Sun. The more pristine the atmosphere, the earlier the generation in which this star was born. Studying stars of different generations allows us to understand the history of the Galaxy - an area of research known as Galactic archaeology.

The local scientists are members of the UVic Astronomy Research Centre (ARC), which includes members from UVic and the National Research Council’s Herzberg Astronomy and Astrophysics institute in Saanich, BC.  The ARC supports communications and collaborations in science, engineering, and computational research related to astronomy and astrophysics.   The ARC was established in 2015, and was granted an NSERC CREATE training program in New Technologies for Canadian Observatories in 2017.  For more information, click 

Contact person:  Kim Venn (, 250 472 5182)

For more info on Pristine, see Kim Venn's interview with CBC News or read this article, which includes a link to the paper.