The international academic journal “Science” presented as its cover this week an image of the Orion Nebula taken by the James Webb Space Telescope (JWST). The Orion Nebula in the photo appears divided into two parts. The one on the bottom left is part of the nebula, while the one on the top right is an area containing hot plasma. In this area, massive stars were captured as they were ionized by deep ultraviolet (FUV) light. Far ultraviolet rays refer to that part of ultraviolet rays whose wavelength is much shorter than that of light.
An international research team led by Olivier Bernat’s French National Center for Scientific Research (CNRS) reported on the 29th (local time) that the “ultraviolet wind” occurring between stars removes gas from the protoplanetary disk of a young star and reduces the brightness of the star. max. time) was published in Science.
Young low-mass stars are surrounded by protoplanetary disks of dust and gas. These disks serve to provide the “raw materials” necessary for the growth of stars.
Previously, academic circles paid attention to why protoplanetary disks do not provide 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 the formation of the planet is dispersed. Photoevaporation is a phenomenon in which high-energy radiation ionizes gas and sweeps 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 gas loss of a protoplanetary disk due to deep ultraviolet rays. This was achieved by observing “d203-506”, a protoplanetary disk located within 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 hit by strong ultraviolet rays, in d203-506. This way it was confirmed that d203-506 was losing mass very rapidly due to the influence of deep ultraviolet rays. As a result of the 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 to form gas.
This study is believed to provide the first evidence confirming the effect of photoevaporation caused by deep ultraviolet radiation on the protoplanetary disk. The research team added: “Since the solar system is composed of numerous stars and clusters, the solar system itself may have been affected by deep ultraviolet rays.”
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