A Canadian-led international team of astronomers have recently discovered spots on the surface of the supergiant star Zeta Puppis that are causing large spiral structures in its stellar wind.

Richard Ignace

Zeta Puppis is a blue evolved massive star, or “supergiant” star. Supergiant stars are the biggest, brightest, and hottest stars in the universe. However, Zeta Puppis isn’t an ordinary supergiant star. While normal massive stars travel in pairs or small groups of stars, it’s considered to be a “runaway” star, traveling on its own at a speed of over 100 kilometers a second.

East Tennessee State University’s own Dr. Richard Ignace is included in the group of astronomers who examined this supergiant celestial body. Ignace is a professor in the College of Arts and Sciences’ Department of Physics and Astronomy and Director of Undergraduate Research and Creative Activities in the Honors College. He has had several noteworthy publications and multiple projects.

“It is very exciting to be published in the Monthly Notices of the Royal Astronomical Society (MNRAS),” Ignace said. “What makes this project unique from the rest is it’s a Canadian-led international project with over 30 amateurs as well as professionals.”

“The goal of the ‘BRIght Target Explorer’ (BRITE) project is to create a long-term model of the star,” Ignace said. “Using nanosatellites, we stared at the star over a five and a half month period. We examined how the light variations evolved overtime and in turn created a picture or a map of the results.”

The observations revealed a 1.78-day periodicity both at the surface and in the wind of Zeta Puppis. The behavior of this periodic signal actually reflects the spinning of the star through the presence of bright spots on the surface. These are causing large, spiral-like structures labeled Corotating Interaction Regions (CIRs) in its wind.

The physical origins of the surface spots and brightness variations on Zeta Puppis remain unknown, requiring further investigations and other types of observations.

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