Where does the stellar matter that flows directly into the region where stars are born come from? – Material flow from nearby young starless cores –

Where does the stellar matter that flows directly into the region where stars are born come from?
– Material flow from nearby young starless cores –

Image of gas flowing from the surrounding reservoir into a star-forming streamer. (Credit: National Astronomical Observatory of Japan)

Recent observations have discovered a structure called a “streamer” in which additional gas, the raw material for stars, flows from the outside into the regions where stars are forming. Recent research has indicated that signs may have been present during the formation of the solar system, and the importance of this research is beginning to be recognized. The outflows are thought to have a major impact on the chemical composition of the stars and planets that eventually form, and are therefore important in studying how planetary environments that support life form.

An international research group made up of members from the National Astronomical Observatory of Japan, the German Max Planck Institute for Extraterrestrial Physics (MPE), Otsuma Women's University, and other institutions is studying the 0-magnitude Perseus region, where stars with masses similar to the Sun give birth to protostar candidate objects.^*1We focused on “Per-emb-2”, which is one of. At Per-emb-2, the presence of the jets was detected by observations previously carried out with the French NOEMA interferometer, but the question remains: “Where does the gas that makes up the jet come from, yet its source is not well understood?” .Therefore, in order to find and investigate the gas flowing in the Per-emb-2 flow device, the research group cooperated with FOREST and Z45, mounted on the 45-meter Nobeyama telescope, which specializes in large-scale “molecular gas distribution probing.” 'Four types of carbon chain molecules using two specific receptors^*2(HC₃N, H.C₅New observations were made of N, CCS, CCH). The goal is to find the origin of the jet, determine the exact mass of the jet itself and its origin, and figure out how long the gas will continue to flow.

During the observation, we obtained a map that broadly covers the northern side of the protostar where the bar can be seen. Figure 1 shows the spatial distribution of various carbon chain molecules obtained by observation. As a result, we found that there are two masses of gas (nuclei) around the tube (mass No. 1 in the figure). Furthermore, by analyzing the velocity spectrum obtained from radio monitoring, it was found that core No. 3 was flowing towards the emitter (core No. 1), and this was identified as the origin of the emitter (=reservoir). The size of this reservoir corresponds to the core of a typical starless molecular cloud. Core 2 was also newly discovered this time, but its relationship to the protostar Per-emb-2 is currently unknown, and we find that more research is needed in the future.

The research group also combined data from individual radio telescopes around the world, such as the Green Bank 100m telescope in the United States and the IRAM 30m telescope in Spain, to identify the HC detected in the Per-emb-2 flow and reservoir device.₃N, carbon dioxide capture, HC₅We performed a detailed analysis of the N status and derived the physical environment (temperature and density) and chemical environment (particle abundance) of the streamer and tank. The results showed that the physical environment of the reservoir resembles the core of a starless molecular cloud before the birth of stars. Moreover, among the molecular species obtained through observation are CCS and HC₃By comparing the nitrogen abundance with the results of chemical reaction network simulations, we found that the reservoir and stream have very young chemical compositions, and both have similar chemical ages. This is also evidence that the core identified this time is material for banners.

Using the results of observations and simulations, we derived the exact masses of the reservoir and stream, which were approximately 16 M⊙ (M⊙: the mass of the Sun, 1 M⊙ equals approximately 1.989×10).³⁰ kg), was calculated to be 13 m⊙. Therefore, the maximum mass of gas that can flow as a stream is about 29 M⊙. In addition, the overall accumulation rate by streamers is approximately 9 × 10 per year^-5 It is derived as M⊙. Once you know the velocity of the gas flow and the total amount of gas, you can calculate the lifetime of the streamer. Assuming all the gas in the reservoir flows into the protostar Per-emb-2, it is estimated that the flow of gas through the stream will continue for 200,000 years, making it a protostar of the magnitude The first.^*3I will answer at the end of the stage. This result means that even during the long period that a star is growing in dense gas, chemically fresh gas can continue to flow in from the outside, constantly changing its chemical properties. In other words, the chemical environment of a planetary system is not constant at the beginning of star formation, but continues to change until the star stops growing. The birth of life on Earth may not have been determined by fate from the beginning, but may have been the result of chance.

In the future, we would like to use ALMA in Chile, South America, to capture places where the chemical composition is changed as gas flows.

Figure 1. Spatial distribution of various carbon chain molecules. The purple cross indicates the location of the protostar Per-emb-2, and the white circle at the top left of each panel indicates the size of the 45-meter Nobeyama telescope.
Top row: (a) HC obtained by FOREST₃N, (b) CCS, (c) CCH results. Vertices (1) and (3) correspond to the streamer and the reservoir.
Bottom row: (d) HC acquired using the Z45 receiver₃n, (e) CCS, (f) HC₅result n. The wave number range observed by the Z45 (45 GHz) is lower than the frequency range observed by the FOREST receiver (90 GHz), so the spatial resolution is different, but the HC₃N and HC.₅In Map N, flows and reservoirs are detected with sufficient spatial resolution.

* Points of this study
This is because we analyzed data not only from the 45-meter Nobeyama telescope, but also from other large single mirrors. To further this research, I stayed at the Max Planck Institute for Extraterrestrial Physics for two months, where they provided me with data from other telescopes and I enjoyed writing my paper while experimenting with new analysis methods. When we got the results of the analysis that explained all the data from the three telescopes without contradiction, it was as if the pieces of the puzzle had fallen into place.

Glossary of terms

*1	0-magnitude protostar candidate object: Because the dipole molecular flow characteristic of protostars has been observed, it is thought to be a young star buried in dense molecular gas that is in the process of being formed. (Reference home page:https://astro-dic.jp/class-0-object/)
*2	Carbon chain molecule: A unique molecule in interstellar space in which carbon atoms are linked by double or triple bonds. More than 130 species have been discovered so far. (Review paper on carbon chain molecules: https://link.springer.com/article/10.1007/s10509-024-04292-9)
*3	First-order protostars: buried deep in the core of the molecular cloud, have interstellar opacity of several tens of orders of magnitude or more, are actively accreting matter, and mass ejection phenomena such as dipole molecular flow are commonly observed. (Reference home page:https://astro-dic.jp/class-i-object/)

Magazine information

This paper was published in The Astrophysical Journal on April 17, 2024. The paper title and affiliation are as follows.
Publishing journal: Astrophysical Journal
Page information: Volume 965, Issue 2, Article No. 162
Sheet name: Per-emb-2 streamer tank
Entertainment: Taniguchi, Kotomi; Pineda, James. Caselli, Paula; Shimoikura, Tomomi; Friesen, Rachel K. Insurance-Cox, Dominic M.; Schmiedeke, Annika
Post URL:https://iopscience.iop.org/article/10.3847/1538-4357/ad2fa1

Members of the research group
Specially Appointed Assistant Professor Kotomi Taniguchi (National Astronomical Observatory of Japan, Scientific Research Division)
Dr. Jaime Pineda (Center for Astrochemical Studies, Max Planck Institute for Extraterrestrial Physics, Germany)
Professor Paula Caselli (Center for Astrochemical Studies, Max Planck Institute for Extraterrestrial Physics, Germany)
Associate Professor Tomomi Shimoekura (Otsuma Women's University, School of Social Information Studies, Department of Environmental Informatics)
Assistant Professor Rachel K. Friesen (University of Toronto, Canada)
Dr.. Dominic M. Segura Cox (University of Texas, USA)
Dr. Annika Schmiedeke (Green Bank Observatory, USA)