Astronomers discover ‘runaway star’

Stars escape their birthplace and eventually disperse throughout the Galaxy. This is an important process in the evolution of the galaxy. Theoretical studies suggest two possible reasons why stars escape. First, stars can be ejected by interactions in young multistar systems. Second, they can also acquire kinetic energy during the collapse or interactions of clouds or molecular clusters. Stars with relatively clear paths often separate completely from their birthplace. In contrast, newborn protostars are often located deep in molecular clouds, making it difficult to measure their dynamical properties. As a result, observational data on runaway stars remains incomplete. However, a joint research team composed of researchers from the National Astronomical Observatory (NAOC) of the Chinese Academy of Sciences (CAS), the Shanghai Observatory (SHAO) of CAS, and Guangzhou University, Using high-resolution molecular spectroscopy lines, a protostar has been detected leaving its birthplace for the first time, providing new observational evidence of the initial state of running stars. hide.

The research was published in the Astrophysical Journal. The researchers used the Atacama Large Millimeter/Submillimeter Antenna Array (ALMA) to perform observations on a large sample of young star-forming regions. In the star-forming region G352.63-1.07, they discovered that the protostellar core had a notable change in velocity. The core was observed in several molecular streams, all of which indicated that the protostar had a different speed than its parent cloud. At the same time, all molecular lines closely track the dense core, providing a unique opportunity to measure stellar motion. According to the spectral velocities of the molecular lines, the protostar exhibits a significant blue shift of -2.3 km/s compared to its original filamentous molecular cloud. At the same time, the core is well placed in the central trough of the parent cloud, suggesting that the core was once part of the interior of the cloud. The escape velocity (-2.3 km/s) and spatial displacement (0.025 light-years) of the core indicate that the escape occurred less than 4,000 years ago, with a kinetic energy of up to 1,045 ergs. This makes the breakout at the center of G352.63-1.07 one of the youngest and most energetic events in the Milky Way’s star-forming regions.

Furthermore, although the escape velocity of the central star is much lower than the escape velocity of high-speed ejecta stars produced in star clusters, it is actually comparable to the dispersion velocity average of young stars. This suggests that cloud collapse is probably the main mechanism for expelling stars. “Stars are the giant nuclear fusion reactors of our universe,” said Professor LI Di, chief scientist of NAOC’s Interstellar Medium Group and co-author of the paper. The runaway star discovered this time is still in its infancy.” “This work captures the initial timing of stellar escape motion in nearby active star-forming regions, such as the Orion Molecular Cloud. This enriches the picture of stellar origins and raises a series of challenges.