They are invisible from Europe; only in the Southern Hemisphere are they visible as bright spots in the southern sky. The Magellanic Clouds are galaxies in the immediate vicinity of the Milky Way and consist of billions of stars. Astrophysicist Prof. Maria-Rosa Cioni keeps her eyes fixed on the Magellanic Clouds from Potsdam, though. The VISTA (Visible and Infrared Survey Telescope for Astronomy) is her eye into space and provides her with a huge amount of data. The large telescope – four meters in diameter – is situated on a side summit of Cerro Paranal in the north Chilean Atacama Desert and is part of the Paranal Observatory of the European Southern Observatory (ESO).
VISTA systematically surveys the night sky in the near-infrared wavelength range of 1 to 2.5 µm. This allows the world's largest survey telescope deep and detailed glimpses into space through haze and dust clouds. The telescope is capable of taking meter-by-meter high-resolution images of the universe, provides insight into the processes of astronomical phenomena, and enables a mapping of the sky. It also focuses on the Magellanic Clouds. While the Large Magellanic Cloud comprises about 15 billion stars, the Small Magellanic Cloud contains about 5 billion.
Understanding the geometry of these galaxies
Italian-born astrophysicist Maria-Rosa Cioni is particularly interested in dwarf galaxies because they are influenced by their proximity to the Milky Way. The two galaxies also interact with one another, which Cioni investigates as head of the large-scale research project VISTA Magellanic Cloud Survey. It is one of six surveys of the southern sky. “We especially want to understand the geometry of these galaxies, the motions of their stars as well as their entire orbital motion,” explains Cioni, who recently received one of the world's major acknowledgements for young scientists: the Consolidator Grant of the European Research Council (ERC). Since 2012, she has been doing research at the Leibniz Institute for Astrophysics Potsdam (AIP) and has been a visiting professor at the Institute of Physics and Astronomy of University of Potsdam. The Magellanic Clouds are ideal for her studies, because they are still easily viewed from Earth. “There are many galaxies in the universe that interact with each other, but they are so far away that we are rarely able to observe individual stars,” Cioni explains.
Cioni and her 20-member international team have been awarded 2000 hours of observation time at VISTA for the Magellanic Cloud Survey. Researchers want to use the data provided by the telescope to model the galaxies and their movements on a computer. Their calculations should allow glimpses both into the past and the future of the galaxies. “We can measure star positions and star movements very accurately with our devices,” Cioni explains. VISTA can capture star movements inside the Magellanic Clouds in the range of milliarcseconds per year - a milliarcsec is about the size of a dime atop the Eiffel Tower as seen from New York City. Billions of stars are measured, and their orbit is extrapolated from the data. Using VISTA, astrophysicists also determine other important metrics such as spectra, brightness, and the chemical composition of stars. Based on these measurements, they develop galaxy models that map the forces acting within them. The positions of individual stars and star groups and their calculated orbital speed and movements reveal gas and mass distribution within galaxies and in the interactions between them.
The data from the Chilean Cerro Paranal go through a complicated procedure before appearing on Cioni’s screen, where she can edit them in tables, mathematical equations, and graphs. “In fact, the data initially go to the UK,” she explains. “The moment the data are recorded by the telescope, they are directly transmitted to Cambridge.” There they are prepared for further examination and are then forwarded to Edinburgh, where they are edited again. Only once the vast amount of data has already been roughly filtered, categorized, and combined are they available to astrophysicists. “You need this infrastructure and an experienced team because the raw data are simply too comprehensive,” she emphasizes.
“Science as such excites me and makes me happy”
If the desired numbers are there, Cioni begins to “juggle” them, integrates them into her models, and visualizes them in pictures and diagrams. It is this number game on the computer – this sorting, thinking, and calculating – that she loves so much, for which she often has to carve out some time from reading and writing articles and research proposals or preparing conferences and lectures. “I would have probably been happy in another field as well,” she says. After all, she studied mathematics, which laid the groundwork to conduct research in a variety of scientific fields. “But astronomy fascinates me. It is exciting to discover what is out there, and we are part of it. However, it is science itself that excites me and makes me happy.” The Magellanic Clouds have been Cioni’s research focus since 2009. The vicinity to the Milky Way may one day prove fatal to the dwarf galaxies. Astrophysicists assume that the Milky Way could absorb smaller galaxies since it is much more massive. Stars and dust of the Magellanic Clouds are likely to change their movements so drastically that they will no longer form separate galaxies but instead merge with the Milky Way. “The small galaxies could be completely torn apart. We assume that this has already happened with many galaxies that we can no longer see,” explains Cioni. The Magellanic Clouds are perhaps only two “survivors” of a once larger galactic group.
Gaia spacecraft records about 40 million stars daily
Magellanic Cloud Survey will end in 2018 after nine years of research. Starting in September 2016, Cioni will have access to more data coming from the Gaia spacecraft launched in 2013. Researchers hope to get more precise measurements of the positions and movements of the stars in the Milky Way and, above all, more accurate spectral measurements that reveal more about the composition of matter. The Gaia spacecraft records about 40 million stars daily, including parts of the Magellanic Clouds, during its planned five-year flight. For Cioni, this will result in enormous volumes of data that will have to be evaluated and analyzed. After the project ends, she will continue exploring the Magellanic Clouds. “Then we will proceed with the next step, focusing on the chemical composition of galaxies. There is still much to discover.”
Prof. Maria-Rosa Cioni studied astronomy at the University of Bologna (Italy) and obtained her PhD degree at the University of Leiden (Netherlands). At present, she is a guest researcher at the Leibniz Institute for Astrophysics Potsdam (AIP) and DAAD Visiting Professor at the University of Potsdam.
Leibniz-Institut für Astrophysik Potsdam (AIP)
An der Sternwarte 16, 14482 Potsdam
Leibnitz Institute for Astrophysics Potsdam (AIP)
The key topics of the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory, founded in 1700, and of the Astrophysical Observatory of Potsdam, founded in 1874. The latter was the world's first observatory to focus explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.
Text: Heike Kampe
Translated by: Susanne Voigt
Published online by: Daniela Großmann
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