2024-03-02 23:38:00
The international academic journal ‘Science’ featured an image of the Orion Nebula taken by the James Webb Space Telescope (JWST) as its cover this week. The Orion Nebula in the photo appears to be divided into two parts. The lower left is part of the nebula, and the upper right is an area containing hot plasma. In this area, massive stars were captured being ionized by deep ultraviolet (FUV) light. Far ultraviolet rays refer to the part of ultraviolet rays whose wavelength is much shorter than that of light.
An international joint research team led by Olivier Bernat’s French National Center for Scientific Research (CNRS) reported on the 29th (local time) that the ‘ultraviolet wind’ that occurs between stars removes gas from the protoplanetary disk of a young star and reduces the star’s mass. time) was published in Science.
Low-mass young stars are surrounded by protoplanetary disks of dust and gas. These disks serve to provide the ‘raw materials’ necessary for stars to grow.
Previously, academic circles paid attention to the reason why protoplanetary disks do not supply enough gas for the growth of young stars. The theoretical model so far has been that when a protoplanetary disk is exposed to external radiation, photoevaporation by ultraviolet rays occurs and the gas necessary for planet formation is dispersed. Photoevaporation is a phenomenon in which high-energy radiation ionizes gas and blows away the atmosphere of a celestial body. It was difficult to observe this phenomenon using existing technology.
In this study, we observed for the first time the process of a protoplanetary disk losing gas due to deep ultraviolet rays. This was achieved by observing ‘d203-506’, a protoplanetary disk located inside the Orion Nebula, using JWST and the Giant Space Telescope in the Atacama Desert, Chile.
The research team observed and analyzed the photodissociation region (PDR), an area where the surface of the protoplanetary disk is affected by strong ultraviolet rays, in d203-506. Through this, it was confirmed that d203-506 was losing mass very quickly due to the influence of deep ultraviolet rays. As a result of calculations, it was estimated that the rate of mass loss in d203-506 could almost eliminate gas from the disk within 1 million years, suppressing the ability of gas to form.
This study is evaluated as providing the first evidence confirming the effect of photoevaporation caused by deep ultraviolet rays on the protoplanetary disk. The research team added, “Recent studies of the solar system indicate that the solar system formed in a star cluster containing one or more massive stars, so the solar system itself may have been affected by deep ultraviolet light.”
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