Astronomers using the ALMA X-ray observatory have discovered complex organic molecules around the young star V883 Orion. As a result of an unexpected outburst on this star in a protoplanetary disk, molecules that were previously in the form of solid compounds were released into the gas phase. The chemical composition of this disk turned out to be close to the composition of comets detected in the modern solar system. Highly sensitive observations made using the ALMA radio observatory allowed astronomers to reconstruct the evolution of organic molecules from the birth of the solar system to the present day.
This research team, led by Jeong-Eun Lee from Kyonghi University, Republic of Korea, used the Atacama Large Millimeter / submillimeter Array (ALMA) radio telescope to detect complex organic molecules, including methanol (CH3OH), acetone (CH3COCH3), acetaldehyde (CH3CHO), methyl formate (CH3OCHO) and acetonitrile (CH3CN). In this study, the first unambiguous detection of acetone in the region of the circumstellar disk, in which planets are formed, was carried out.
Usually, organic molecules in the gas phase are found only at a relatively short distance from the star, which is several astronomical units (1 AU is equal to the average distance from the Earth to the Sun), and then the so-called snow line passes, beyond which substances turn into ice and can not be observed using radio telescopes. In the case of the star V883 Orion, the organics was found at a much greater distance from the star – it turned out that organic molecules form a thin ring with a radius of about 60 AU. around the star.
Such an unusual distribution of organic molecules around this star is explained by the fact that closer to the luminary, the organic is hidden from observation by a layer of dust, and a snow line passes right along the outer edge of the ring observed in the radio range, beyond which organic compounds are no longer found in the form of individual molecules, and instead form crystals on particles of inorganic dust. The observed distribution of organic molecules in the vicinity of the V883 Orion star, located about 1300 light years from Earth, was formed relatively recently, the authors note. This is due to the fact that a so-called Orion FU flash occurred at the star, in which the brightness of the star increases significantly as a result of a large amount of material flowing to the star from the protoplanetary disk. Such flashes are astronomically short-lived events lasting for about 100 years and are accompanied by a shift of the snow line to the periphery of the star’s protoplanetary disk. Thus, in the course of these observations, scientists were able to observe fresh organic material, which only recently sublimated from the solid state to the gas phase. These observations have provided valuable information about organic molecules, which may be the building blocks of more complex bio-organic compounds, the authors note.
Organics around the young star
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