The Sun is not stationary but is actually orbiting the Milky Way galaxy at a rate of 220 kilometers per second. Recently, a hypervelocity L subdwarf star named J1249+36 was discovered racing through the Milky Way, potentially on a trajectory to leave the galaxy altogether. This discovery was made possible by the Backyard Worlds: Planet 9 citizen science project involving over 80,000 volunteers and a team of astronomers led by Adam Burgasser from the University of California San Diego. The star’s speed of 600 kilometers per second makes it a potential “hypervelocity” star.
To further study J1249+36, the W.M. Keck Observatory in Hawaii was used to measure its infrared spectrum, revealing it as a rare L subdwarf, representing the oldest stars in the Milky Way. Atmosphere models created by Roman Gerasimov allowed for an accurate match between the observed and predicted spectrum of J1249+36. The team also used imaging data from ground-based telescopes to measure the star’s position and velocity in space, predicting its orbit through the Milky Way. With its speed and trajectory, J1249+36 has the potential to escape the Milky Way.
Researchers proposed two possible scenarios to explain J1249+36’s trajectory. In the first scenario, the star was once a low-mass companion of a white dwarf that exploded as a supernova, giving the companion star a kick. In the second scenario, J1249+36 may have originated from a globular cluster and interacted with a black hole binary that expelled it. Further research is needed to determine the star’s elemental composition and identify a chemical fingerprint that could pinpoint its origin, whether from a supernova event or a globular cluster.
Future studies involving J1249+36 could shed light on the history and dynamics of the Milky Way, revealing more about the origins of hypervelocity stars and their unique trajectories. By examining the star’s abundance patterns and potential pollution from a supernova explosion, researchers aim to uncover the origins of J1249+36 and understand the mechanisms that have propelled it through the Milky Way. Despite the uncertainty surrounding the star’s past, its discovery presents a valuable opportunity for astronomers to expand their knowledge of our galaxy’s evolution.
The citizen science project Backyard Worlds: Planet 9 played a crucial role in the discovery of J1249+36, highlighting the importance of collaboration between volunteers and professional astronomers in identifying celestial objects with unique properties. The star’s high velocity and potential escape from the Milky Way provide a fascinating puzzle for scientists to solve, opening up new avenues for research into the mechanisms behind hypervelocity stars. Through continued observation and analysis, researchers hope to unravel the mystery of J1249+36’s origins and better understand the complex interactions that shape our galaxy’s dynamics.