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IU high performance computing resources facilitate international survey of stars

Slate and Slate Project store Milky Way star data, with complex image processing carried out with the IU Carbonate supercomputer

Our home galaxy is bulging, and there's an international research effort underway to learn more about it and find out what it can tell us about the Milky Way overall.

The work involved aiming a telescope at an area of the Milky Way known as the Southern Bulge, located near the giant black hole at the center of our spiral-shaped galaxy, to survey a quarter of a billion stars. As one of the largest surveys of these stars, the BLANCO Dark Energy Camera, or DECam project, processed hexagonal-shaped, information-dense images from 14 nights' worth of data from the Victor M. Blanco telescope in Chile. Researchers used six different filters, ranging from ultravioloet to near-infrared readings, to analzye the stars and obtain accurate measurements of their brightness.

“We want to know what kinds of stars are in the bulge, how do they differ from the stars in the spiral arms?” said Catherine Pilachowski, a professor of astronomy at Indiana University Bloomington who is part of the effort to better understand Earth’s home.“What role does the bulge play in the formation of the spiral arms and stars themselves, in the way that stars move around the galaxy and the composition of the galaxy? Are stars still forming in the bulge? Is it really old? Are there young stars in the bulge mixed with older stars?” 

In the telescope’s crowded field of stars, overlapping objects and interference from space dust require a supercomputer system to process the photometric data accurately. Mike Young and Scott Michael at IU Research Technologies, in collaboration with Christian Johnson at the Space Telescope Science Institute, spent several weeks facilitating the large-scale data management of the data collected from the telescope.

The storage capabilities of Slate and Slate Project were originally housed on Data Capacitor 2 before it was decommissioned in 2021. This storage, combined with the processing power of the Carbonate supercomputer, powered the BLANCO DECam survey’s ability to include existing data on the bulge from the European Space Agency’s Gaia satellite mission. 

“With Gaia’s astrometric data showing the motions of stars added to our photometry, we can identify which stars are members of an individual cluster. This gives us tremendous ability to analyze the stellar populations in the bulge in a dynamic way,” said Pilachowski. 

Scott Michael, director of RT’s Research Software and Solutions directorate, said, “The ongoing and extensive collaboration between Research Technologies and the IU astronomy department allowed us to be able to provide our facilities and know-how for this project, and we look forward to continuing to host this wellspring of data about our corner of the universe.” 

Justin Kader, a PhD student of Pilachowski's whose research focuses on ancient stars from the earliest epochs of our galaxy's formation, is already using the resource to develop new insights about globular star clusters in the Bulge.

“The photometric catalog offers precise, high-sensitivity broadband photometry of more than 250 million stars, and it allows us to study the chemical composition of the stars in these ancient clusters,” said Kader. “This provides us with valuable clues to unresolved problems like how globular clusters form and what role they might play in the formation and evolution of galactic bulges like the Milky Way's." 

Pilachowski's work on the project was funded by the National Science Foundation.