Stars escape from where they were born and eventually disperse throughout the galaxy. This is an important process in galactic evolution. Theoretical studies suggest two possible reasons for star escape. First, stars may be thrown out by interactions in young multiple star systems. Second, they can also gain kinetic energy during the collapse or interaction of molecular clouds or clumps.

Stars with relatively clear orbits are often completely separated from their birthplace. In contrast, young protostars are often deeply embedded in molecular clouds, making their kinematics difficult to measure. As a result, observational data on outgoing stars is still very lacking.

But now, using high-resolution molecular spectral lines, a joint team of researchers from the National Astronomical Observatories (NAOC) of the Chinese Academy of Sciences (CAS), CAS’s Shanghai Observatory (SHAO) and Guangzhou University have, for the first time, obtained a preliminary star leaving its birthplace, thus providing new observational evidence of the initial state of runaway stars.

The study was published on: Astrophysical Journal.

Researchers used the Atacama Large Millimeter/Submillimeter Array (ALMA) to observe a large sample of young star-forming regions.

They found a protostellar core with a noticeable velocity change in the star-forming region G352.63-1.07. The nucleus has been observed in a number of molecular lines; all of which indicated that the protostar had a different velocity than its parent cloud. At the same time, entire molecular lines precisely follow the dense core, providing a unique opportunity to measure the motion of stars.

According to the spectral velocity of the molecular lines, the protostar has a significant blueshift of -2.32.3 km/s relative to the main filamentous molecular cloud. At the same time, the core is correctly positioned in the central part of the main cloud; This shows that the core was previously the inner part of the cloud.

The escape velocity (–2.3 km/s) and spatial displacement (0.025 light-years) of the core indicate that escape occurred less than 4000 years ago with kinetic energy up to 10 45 erg. This makes the core outflow in G352.63-1.07 one of the youngest and most energetic events in the star-forming regions of the Milky Way.

Moreover, although the escape velocity of the central star is much lower than that of high-velocity ejected stars forming in star clusters, it is actually comparable to the average dissipation velocity of young stars. This suggests that cloud collapse must be the primary mechanism of movement of escaping stars.

“Stars are giant nuclear fusion reactors in our universe. The runaway star detected this time is still in its infancy,” said Professor Lee Di, principal scientist of NAOC’s Interstellar Intermediate Group and co-author of the paper. “This work instantly captured the first moment of stellar motion in nearby active star-forming regions such as the Orion Molecular Cloud. This enriches the picture of the origin of stars and raises a number of problems.” Source