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The dust in our Milky Way is the constituent of the cosmic life cycle. It is the substance from which new stars are generated and it is what stars become once they die. Unfortunately, as HANS-WALTER RIX explains in this video, the dust turns distance measurements of stars in the Milky Way into a difficult endeavor, because it dims objects and blocks light from the material behind it. In his project two common methods of distance measurement are therefore used in combination to sketch a 3D map of Milky Way dust: first the parallax, which uses the orbit character of the earth in order to check on the stars’ respective positions, and second, the calculated brightness of stars which allows for an estimate concerning the amount of dust in front of each star. The so created 3D map helps to limit errors in distance calculations due to a feasible dust exclusion, made possible by the localization of dust. The conversion of observed quantities into physical quantities thus becomes possible.


Hans-Walter Rix is Director at the Max Planck Institute for Astronomy in Heidelberg; he is also an Honorary Professor at the University of Heidelberg in Germany. Upon completion of his PhD at the University of Arizona (Tucsan) he was awarded a Hubble Fellowship, which he took to the Institute for Advanced Studies in Princeton. There, he worked on some of the first Hubble Space Telescope data on gravitational lensing. His fields of research are galaxy evolution and galaxy structure, which he investigates by means of spectroscopic and imaging surveys, currently focusing on the Milky Way as a "galaxy model organism". Rix is a member of the German National Academy of Sciences, the Leopoldina.


Max Planck Institute for Astronomy

At the Max Planck Institute for Astronomy (MPIA), we investigate the cosmos, its structure, and evolution at all spatial scales. Some of the questions the astronomers try to answer are: How did the first galaxies and stars form and evolve? What is the role of black holes in the evolution of galaxies and the interstellar medium from which new stars are born? What conditions and processes lead to the birth of new stars? How do planets form? What kind of planets are out there, and are there any of them potentially sustaining life? How did life evolve on Earth? The scientists’ expertise comprises disciplines such as physics, chemistry, biology, and computer science. For their research, MPIA astronomers employ observations with telescopes, computers to model complex systems and processes, and lab experiments to mimic chemical reactions in space. The MPIA, founded in 1969, is part of the Max Planck Society. MPIA scientists use state-of-the-art research facilities worldwide, both on the ground and in space, to which the institute supplies instrumentation like cameras and spectrographs. Over the years, MPIA’s engineers have acquired unique and valuable experience building instrumentation for telescopes, which is highly demanded by numerous domestic and international partners.

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Original publication

A Three-dimensional Map of Milky Way Dust

others, Green Gregory M., Schlafly Edward F., Finkbeiner Douglas P., Rix Hans-Walter, Martin Nicolas, Burgett William, Draper Peter W., Flewelling Heather, Hodapp Klaus and Kaiser Nicholas
The Astrophysical Journal
Published in 2015