G206.93-16.61E2 is close to the reflection nebula NGC 2023 in the Orion B molecular cloud. The zoom-in pictures show the 1.3mm continuum emission (blue) and CO molecular outflow (orange) of ALMA observation. These observations develop an in-depth understanding of the formation of multiple star systems in the early stage. Credit: SHAO
inese astronomers have discovered a forming quadruple star system within a core by observing Orion’s giant molecular clouds with the ALMA radio telescope. Previously, a widely separated quadruple star system had been reported in its early stage. The quadruple star system discovered in the new study, published in The Astrophysical Journal Letters, exhibits more compact inter-member and more complex star formation activities, providing a diverse perspective for understanding the formation of multiple star systems, reports the Chinese Academy of Sciences. Approximately half of the stars in the Galaxy reside in systems with two or more stars. Knowledge of how multiple star systems form is essential to building comprehensive theories of star formation and planet formation. All stars form in the densest region of gas in the molecular cloud known as the “dense core.” Previous observation has shown that there are more “star babies” in a star system the smaller the proportion they occupy in the whole. For higher order stellar systems with more than two stellar members, how they form in dense cores remains ambiguous due to insufficient observations. Existing models suggest that multiple star systems form through the fragmentation of a cloud core in its early evolution. To explore the origin of multiple star systems, the ALMASOP (ALMA Survey of Orion Planck Galactic Cold Clumps) team conducted a high-resolution investigation of 72 young, cold nuclei in Orion’s giant molecular clouds. The scientists observed the thermal emission of dust at a wavelength of 1.3 mm. They discovered a quadruple protostellar system in G206.93-16.61E2, a cold, dense core located 1,500 light-years from Earth within the giant molecular cloud Orion B. The system consists of four members: two protostars and two condensations of prestellar gas. which may also form low-mass stars in the future.
The scientists found that the largest separation of the four members of the system is only a thousand astronomical units. “The exceptional compactness and close proximity of this system is a fascinating discovery. The analysis suggests that this system is very likely to form a gravitationally bound quadruple star system in the future,” said Dr. LUO Qiuyi of the Astronomical Observatory in a statement. of Shanghai (SHAO) and first author of the study. The scientists also discovered several elongated, ribbon-like structures in the dust emission, tightly binding the four limbs and extending outward. To discover the role of the continuous ribbons, the scientists compared a similar quadruple system in a numerical simulation with the result of observation. They revealed that stretching continuous ribbons can act as transporter funnels, transporting gaseous materials from the outer shell/core to protostars, and connecting newborn member stars as gas bridges. “The simulation supports that these ribbons can serve as large-scale accretion streamers. Therefore, the two condensations of gas in the system have the potential to form a star that depends on feeding from these continuous ribbons,” explained Professor LIU Tie, who led the study. “Accretionary streamers could also fragment and form new stars.” In addition, the observations revealed intricate flows of gas driven by protostars in the system, potentially viewed from a polar perspective. In the crowded environment of the birthplace, some materials supplied by accretion flows are lost through outflows, which could impact the evolution of your system.
source:https://arxiv.org/abs/2306.07839