3D PDFs Yield Star Formation InsightsJanuary 2009
Jaime Pineda & Jonathan Foster
This image shows a very long-exposure view of a 1-degree- square area within the Perseus star-forming region. The colors correspond approximately to "true" color, and the regions which appear very dark show the obscuration caused by concentrations of interstellar dust associated with the star-forming cores discussed in the Letter in Nature. The image gives an impression of the generally "turbulent" (swirling) nature of interstellar material in star-forming regions. This is a "flat" image of the sky, in that it does not contain any information about depth. The "3D" images published in Nature show views of this region taken with radiotelescopes where the line-of-sight velocity of gas is used to separate regions at different distances, which appear super-imposed on each other in this more traditional flat optical image. | New computer visualization technology developed by the Harvard Initiative in Innovative Computing has helped astrophysicists understand that gravity plays a larger role than previously thought in deep space’s vast, star-forming molecular clouds.Reported in the Jan. 1 issue of the journal Nature, the insight is illustrated in the journal’s online version through new three-dimensional PDF technology that will allow readers to view the article’s key graphics using free PDF software already commonly found on computers. The work was led by Astronomy professor Alyssa Goodman of Harvard’s Faculty of Arts and Sciences, the Harvard-Smithsonian Center for Astrophysics, and the Initiative in Innovative Computing (IIC), of which she was the founding director. Goodman and colleagues used the IIC technology to examine reams of astronomical data collected on a structure known as a giant molecular cloud. Previous technology, Goodman says, doesn’t allow for careful consideration of what she described as “hierarchical” structure — essentially regions within regions — and would have obscured specific details in the molecular cloud, such as nested areas of varying density and a physical break from one area to another. “There’s no way of noticing this without being able to see this in 3-D,” Goodman said. Michael Halle, senior scientist at the IIC and instructor in radiology at Harvard Medical School and Brigham and Women’s Hospital, says this research shows that visualization technology is a critical part of the analysis and discovery process and not just a way to display data once it has been gathered, analyzed and understood. The research team took advantage of tools developed by the IIC’s ongoing Astronomical Medicine (A-M) project, managed by Halle, which uses technology devised for medical imaging on astronomical research. To visualize the molecular cloud in three dimensions, it used Astronomical Medicine’s 3-D Slicer program, originally devised to analyze medical images. The key advance, however, is a new computer algorithm - developed by Erik Rosolowsky of the University of British Columbia - which outputs results in a “dendrogram,” a treelike representation of data. From the dendrogram, researchers were able to create 3-D displays of the data that they could then rotate and examine from many different directions. The data, which are part of the ongoing COMPLETE (COordinated Molecular Probe Line Extinction Thermal Emission) Survey of Star Forming Regions, measure emission from a type of carbon monoxide molecule in the cloud. The research will be presented in a novel way for Nature, Goodman said. It will be the first time a major scientific journal has used a 3-D PDF of graphics in an article. The 3-D PDF format has been used before, primarily in manufacturing and advertising. Source: HarvardScience
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