Recently, a remarkable cosmic discovery came to light when citizen scientists, participating in the Backyard Worlds: Planet 9 project, spotted a faint red star moving at an astonishing speed of approximately 1.3 million miles per hour (600 kilometers per second). This velocity is so intense that it could potentially allow the star to escape the gravitational pull of the Milky Way galaxy and venture into intergalactic space. If confirmed, this star, designated CWISE J124909.08+362116.0 or J1249+36, would be the first known hypervelocity low-mass star, marking a significant milestone in astronomical research.
The concept of hypervelocity stars was first theorized in 1988 and confirmed with discoveries starting in 2005. These stars are exceedingly rare, and the discovery of J1249+36 adds to the intrigue surrounding low-mass stars, which are generally more abundant than their high-mass counterparts. According to Roman Gerasimov, a postdoctoral research fellow at the University of Notre Dame and coauthor of the study, low-mass stars are challenging to detect due to their cooler temperatures and lower luminosity. This makes the identification of J1249+36 particularly exciting for the scientific community.
Citizen scientists played a crucial role in this discovery by analyzing data from NASA's Wide-field Infrared Survey Explorer mission. The project encourages volunteers to search for patterns and anomalies in images collected between 2009 and 2011. Martin Kabatnik, a citizen scientist from Nuremberg, Germany, expressed his excitement upon discovering the star's rapid movement, believing it must have already been reported due to its extraordinary speed. Follow-up observations from various telescopes, including the W. M. Keck Observatory in Hawaii, helped confirm the findings and solidify the star's unusual trajectory.
J1249+36's classification posed challenges for astronomers, as its low mass raised questions about whether it was a low-mass star or a brown dwarf. Brown dwarfs, which are more massive than planets but not quite stars, have been previously identified by citizen scientists in the Backyard Worlds project. However, none of those brown dwarfs exhibited the high-speed trajectory characteristic of hypervelocity stars. By utilizing data from multiple telescopes, including the Pan-STARRS telescope, researchers were able to determine that J1249+36 is likely an L subdwarf, a cooler and less massive type of star.
The study's authors suggest two possible scenarios for how J1249+36 ended up on its rapid escape trajectory. One hypothesis is that the star was once a companion to a white dwarf, which underwent a supernova explosion, ejecting J1249+36 into space. This interaction would have provided the star with the necessary velocity to break free from the Milky Way's gravitational grip. The second scenario posits that J1249+36 originated in a globular cluster, where gravitational interactions with a black hole could have propelled it out of the cluster and into its current path.
Understanding the nature of J1249+36 could offer insights into the broader population of hypervelocity stars and their origins. The chemical composition of the star may serve as a "fingerprint" to trace its origins back to its stellar nursery, whether it be a globular cluster or a binary system involving a white dwarf. As researchers continue to analyze the star's elemental makeup, they hope to uncover more details about its formation and the events that led to its extraordinary speed.
The discovery of J1249+36 not only highlights the contributions of citizen scientists but also emphasizes the importance of collaboration between amateur astronomers and professional researchers. As the scientific community delves deeper into the properties of this hypervelocity star, it opens new avenues for understanding the dynamics of low-mass stars and their role in the evolution of the Milky Way galaxy.
