What can fast-spinning stars known as “blue lurkers” teach us about star formation and evolution? This is what a recent study being presented at the 245th American Astronomical Society meeting hopes to address as a team of researchers investigated the potential processes responsible for how an unusually fast-spinning blue lurker-white dwarf star within the open star cluster M67 could have evolved into what we see today. This study has the potential to help researchers better understand the formation and evolution of stars throughout the cosmos and what mysterious behavior they can exhibit.
Located approximately 2,800 light-years from Earth, M67 is estimated to be between 3.2 and 5 billion years old. While the exact number of stars within M67 remains up for debate, astronomers used NASA’s Hubble Space Telescope to identify this blue lurker as being part of a triple star system with the appearance of our Sun. However, it’s the unique spin rate of this star that grabbed the attention of astronomers, who postulate that it gathered material from one of the two other stars, resulting in a spin rate of four days. For context, Sun-like stars typically take approximately 30 days to complete one orbit.
"Blue lurker" star evolution in a triple system. Panel 1: Normal triple star system with three Sun-like stars. Panel 2: The two closer stars merge to create a massive star. Panel 3: The new massive star becomes a giant star, resulting in some of the material traveling to the orbit of the outer star, which grows in both size and rotation speed. Panels 4-5: The massive star burns out over time, forming a massive white dwarf as the outer star travels inward toward the massive star, resulting in a binary star system with a closer orbit. Panel 6: The surviving outer star looks like our Sun but nicknamed a "blue lurker." (Credit: NASA, ESA, Leah Hustak (STScI))
"This is one of the only triple systems where we can tell a story this detailed about how it evolved," said Dr. Emily Leiner, who is an assistant professor of physics at the Illinois Institute of Technology and lead author of the study. "Triples are emerging as potentially very important to creating interesting, explosive end products. It's really unusual to be able to put constraints on such a system as we are exploring."
Aside from blue lurkers, the researchers note that triple star systems could also help scientists better understand other celestial objects, including supernovae, white dwarf binaries, X-ray binaries, and blue stragglers.
What new discoveries about blue lurkers will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: AAS 245, EurekAlert!, NASA
