[연구필요성]
By understanding how organic molecules, which are the origin of life, are created and evolved to be included in planets in the process of star formation similar to our solar system, we explore the origins of the solar system and the birth of life on Earth.
[연구성과/기대효과]
Organic molecules such as H2CO, CH3OH, HCOOH, and C2H5OH were detected in the icy state around the embryonic star. Unlike previously observed simple ice molecules such as water (H2O), carbon monoxide (CO), and carbon dioxide (CO2), organic molecular ice is very small in amount, making it difficult to detect with previous observation equipment. Using the high-performance spectrometer of the James Webb Space Telescope, which has excellent light-gathering power, it was possible to observe the weak absorption lines of these organic molecules in the icy state. If the spectrum of gaseous organic molecules observed by the giant radio interferometer telescope ALMA and the spectrum of organic molecules in the ice state observed by the James Webb Space Telescope are combined and studied comprehensively, the chemical reaction of organic molecules occurring on the surface of space dust It is expected that we will be able to make groundbreaking progress in the study of evolutionary processes.
[본문]
An international joint JWST cycle 1 project team consisting of 14 astronomers from Japan, Korea, the United States, and the Netherlands succeeded in detecting the ice spectrum of complex organic molecules for the first time around a fetal star.did. The project is being led by Dr. Yao-Lun Yang, a researcher at RIKEN in Japan. In Korea, Seoul National University Department of Physics and Astronomy Professor Jeongeun Lee, Research Fellow Student Cheolhwan Kim, and Korea Astronomy and Space Science Research Institute postdoctoral researcher Dr. Jaeyoung Kim participated.are doing
The research team is using the Mid-Infrared Instrument (MIRI) mounted on the James Webb Space Telescope to probe molecular ice in four very young embryos, one of which, IRAS15398-3359, has passed It was observed as the first exploration target in May. IRAS15398-3359 is a young embryonic star in the center of a dark molecular cloud called Lupus I, regarding 500 light-years from Earth (Figure 1).
Named CORONIS (COMs ORigin Investigated by the Next-generation Observatory in Space), the main mission of the project is to investigate how many organic molecules and what composition are in the icy material around the embryonic star. What we ultimately want to know through this investigation is how organic molecules, which are the origin of life, are created and evolved to be included in planets in the process of forming stars similar to our solar system, that is, how we came to exist here. Humanity has now reached a critical juncture in obtaining answers to these ultimate questions. Using the JWST, it is possible to observe the star-forming region similar to the early solar system at a level of resolution and sensitivity previously unimaginable, and probes such as Hayabusa 2 can directly sample samples containing materials from the early solar system formation. because it can be collected and analyzed.
Since scientists believe that organic molecules such as methanol and ethanol are the origins of life on Earth, they have been very interested in where and through what chemical process these organic molecules are made. About 20 years ago, organic molecules began to be discovered where stars are formed and in comets, which are celestial objects in the solar system. These organic molecules are thought to be made in an ice state on the surface of cosmic dust, but so far, all organic molecules found outside the solar system have been observed in a gaseous state. This is because observational equipment was not good enough to detect icy organic molecules where stars form.
Molecules in the ice state absorb the light of celestial bodies that emit infrared rays and use it as vibrational energy. By observing the resulting absorption spectrum, the type and amount of molecules in the ice state can be studied. In the past, absorption spectra of ice molecules such as H2O, CO, CO2, and CH4, which are relatively abundant, have been observed by the Spitzer Infrared Space Telescope and the AKARI Infrared Space Telescope.
However, organic molecular ice is very small in quantity, so a large telescope with good light-gathering power and a very good spectrograph are essential to detect it. This discovery was made possible thanks to JWST, the first observation system in human history that satisfies these conditions. The JWST has 100 times higher sensitivity and 10 times better resolution than previous infrared space telescopes, allowing organic molecules in the gaseous state to be decomposed and observed to the immediate vicinity of the observed fetal star, thus enabling chemical research that takes place in the ice state. is making significant progress.
With this observation, the CORINOS project very clearly detected CO2, H2O, and CH4, which are simple ice molecules, and H2CO, CH3OH, and HCOOH, which are organic molecules, in the mid-infrared spectrum in the range of 5 to 28 microns, as well as C2H5OH and CHCHO, although weak. (Figure 2). In addition, emission spectra of H2, CO, and H2O, which are neutral molecules, and emission spectra of Ne+ and Fe+, which are ionic atoms, were also detected. . These interactions were also well captured in images obtained with a mid-infrared camera (Fig. 3).
Observations of the remaining three embryonic stars of the project, led by Dr. Yao-Lun Yang, will take place next spring. At the same time, COMPASS (Complex Organic Molecules in Protostars with ALMA Spectral Surveys), an ALMA Cycle 9 Large Program co-responsible by Prof. Jung-Eun Lee with European and American astronomers, has identified 11 fetuses, including IRAS15398-3359 observed with JWST. A gaseous organic molecule survey of the star will be conducted in the first half of 2023. Combining the composition and content of icy organic molecules observed with JWST and gaseous organic molecules observed with ALMA will be the first attempt to understand how organic molecules form and evolve during star formation. The Korean team, led by Professor Jeongeun Lee, is expected to make an important contribution to the interpretation of observational results by performing theoretical chemical model calculations as well as analysis of observational data in both projects.
The findings were published in the Astrophysical Journal Letters on December 12, 2022.