Amina Helmi’s passion for the Milky Way becomes clear as soon as she walks into her small office at the University of Groningen in the north of the Netherlands.
Next to the family photos and dissertations stacked with inscrutable titles sits a piled bowl of chocolates named after the star system she has spent her career studying.
Digging into the Milky Way’s violent past has earned the 55-year-old astronomer, originally from Argentina, the Kavli Prize, widely seen as the Nobel Prize of astrophysics.
Helmi is a world expert in a field known as galactic archaeology, which aims to decipher what happened to our galaxy in the past and get a glimpse of its future by using stars as “cosmic fossils”.
“We can measure, for example, the amount of chemicals in stars,” Helmi told AFP in an interview.
“It works like a star’s DNA in the sense that they store information about where they were born and in what environment.”
Forget the typical image of an astronomer with eyes glued to a telescope scanning the celestial sphere.
Helm points to the huge data catalogs – sometimes two billion rows of information – that contain precious information about the stars.
The European Space Agency’s Gaia mission, which aimed to form a three-dimensional map of the Milky Way, was a major turning point for Helmi’s research.
“It measured the motions of about a billion and a half stars in a much larger volume than before,” said Helmi, who contributed to the mission herself.
“It wasn’t just the sheer number of objects, but also how accurately we could measure the movements, how precisely.”
– “Speechless” –
Data from the Gaia mission allowed Helm and her team to piece together the events that forever changed our home galaxy.
About 10 billion years ago, long before our Sun and the stars we can see today were born, a dwarf galaxy, Gaia-Enceladus, collided with what was then the Milky Way.
The two merged galaxies and stars now present are part of a halo surrounding our home galaxy.
Young stars were also formed as a result of the cosmic collision, creating a “bulging” disk that is a feature of the Milky Way, she said.
The discovery proved that the Milky Way was formed by a series of collisions with other galaxies, not by a smooth and steady growth as previously thought.
The work earned Helm a share of the Kavli Prize, along with Vasily Belokurov (University of Cambridge) and Rodrigo Ibata (University of Strasbourg).
Helmi also won a share of the $1 million prize fund, a medal and a citation, to be presented in September at a ceremony organized by the Norwegian Academy of Sciences and Letters in Oslo.
The trio of scientists were credited with “discovering fossil evidence of past mergers proving that the Milky Way galaxy was built through hierarchical accretion.”
Helmi admitted she was “completely speechless” when she found out she was to receive the coveted award.
“For me, this is really the biggest there is. And it’s absolutely incredible,” she told AFP.
“I think that even for our field, which is relatively new but has grown tremendously in recent years, this is also a very nice recognition.”
What does the future bring? Helmi looks forward to examining more data from the Gaia mission, as well as working on new ways to model large data sets.
And what does the Milky Way’s turbulent past tell us about the future?
“Nothing much has happened” since then, Helmi said.
“So you could say it’s been a wild youth and now a quiet, calm adulthood.”
