A groundbreaking study has revealed for the first time observed instances of protostars escaping their birthplaces, providing new insights into the early stages of stellar migration and the mechanisms that drive this process during galaxy evolution. Stars dispersed from the regions where they formed and made a significant contribution to the evolution of the Milky Way. Two main mechanisms of dispersion have been proposed in theoretical studies.
First, in a young star system made up of multiple stars, gravitational interactions can cause some stars to be ejected. Second, stars may gain kinetic energy from the process of collapse or the dynamic interaction of molecular clouds or clumps of molecules, causing them to eventually escape into the Milky Way.
Stars with relatively clear trajectories are often completely detached from their birthplace. In contrast, juvenile protostars are often deeply embedded in molecular clouds, making it difficult to measure their kinematic signatures. As a result, observational data on escaping stars are still incomplete.
The departure of a protostar was observed for the first time
Now, however, a joint team of researchers from the National Astronomical Observatories of the Chinese Academy of Sciences, the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, and Guangzhou University has discovered for the first time a protostar that has left its birthplace using high-resolution molecular spectral lines, thus providing new observational evidence for the initial state of the fugitive star. The study was published in the journal Astrophysical Sinica.
The researchers used the Atacama Large Millimeter Wave Submillimeter Wave Antenna Array (ALMA) to observe a large number of samples of young star-forming regions.
In G35263-1.07 Discovery of star-forming regions
In the star-forming region g35263-1.07, they discovered a protostellar core with a significant velocity shift. They observed the core in multiple molecular lines, all of which indicate that the protostar had a different velocity than its parent cloud. At the same time, these molecular lines all closely trace the dense core, thus providing a unique opportunity to measure stellar motion.
Depending on the spectral velocity of the molecular line, the protostar has a significant blueshift relative to its parent filamentous molecular cloud with a velocity of -23 km/s。At the same time, the core is located exactly at the inclination of the parent cloud, which indicates that the core was once part of the molecular cloud.
The escape velocity of the core (-2.)3 km/s) and a spatial offset (0.025 light years) indicates that the escape occurred less than 4000 years ago with kinetic energy of up to 1045 ergs. This makes the G35263-1.The core of 07 escaped and became one of the youngest and most energetic events in the star-forming region of the Milky Way.
In addition, while the escape velocity of the central star is much lower than the high-velocity ejection of stars produced in the cluster, it is actually comparable to the average diffusion velocity of young stars. This suggests that cloud collapse should be the main mechanism driving star escape.
Stars are the giant nuclear fusion reactors in our universe. The discovery of escaping stars is still in its infancy"Professor Li Di, co-author of the article and chief scientist of the Interstellar Media Group of the National Astronomical Observatories, said. "This work captures the initial moments of star escape motion in the active star-forming regions near the Orion molecular cloud, etc. It enriches the picture of the origin of stars and presents a set of challenges"。
In the future, researchers will study G35263-1.07 for a more in-depth analysis of multi-star interactions and ** gas expansion.
Compiled from: scitechdaily