Free Astronomy Magazine September-October 2024

SEPTEMBER-OCTOBER 2024 T his graphic presents some of the results from the MIRI Mid-INfrared Disk Survey (MINDS), which aims to build a bridge between the chemical in- ventory of disks and the properties of exoplanets. In a new study, a science team explored the region around a very low-mass star of 0.11 solar masses (known as ISO-ChaI 147). They found that the gas in the planet-forming region of the star is rich in carbon. This could mean that the build- ing blocks for planets may lack carbon because all of the carbon-containing chemicals have evaporated and been lost into the surrounding gas. As a result, any rocky planets that form might be carbon-poor. The spectrum revealed by NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared In- strument) shows the richest hydrocarbon chemistry seen to date in a protoplanetary disk, consisting of 13 carbon-bearing molecules. This includes the first extrasolar detection of ethane (C 2 H 6 ). The team also successfully detected ethylene (C 2 H 4 ), propyne (C 3 H 4 ), and the methyl radical CH 3 , for the first time in a protoplanetary disk. This graphic highlights the detections of ethane (C 2 H 6 ), methane (CH 4 ), propyne (C 3 H 4 ), cyanoacetylene (HC 3 N), and the methyl radical CH 3 . [NASA, ESA, CSA, Ralf Crawford (STScI)] team’s findings include the first de- tection of ethane (C 2 H 6 ) outside of our solar system, as well as ethyl- ene (C 2 H 4 ), propyne (C 3 H 4 ), and the methyl radical CH 3 . “These molecules have already been detected in our solar system, like in comets such as 67P/Churyumov– Gerasimenko and C/2014 Q 2 (Love- joy),” added Arabhavi. “Webb al- lowed us to understand that these hydrocarbon molecules are not just diverse but also abundant. It is amazing that we can now see the dance of these molecules in the planetary cradles. It is a very differ- ent planet-forming environment than we usually think of.” The team indicates that these results have large implications for the chemistry of the inner disk and the planets that might form there. Since Webb revealed the gas in the disk is so rich in carbon, there is likely little carbon left in the solid materials that planets would form from. As a result, the planets that might form there may ultimately be carbon- poor. (Earth itself is considered car- bon-poor.) “This is profoundly different from the composition we see in disks around solar-type stars, where oxy- gen bearing molecules like water and carbon dioxide dominate,” added team member Inga Kamp, also of the University of Groningen. “This object establishes that these are a unique class of objects.” “It’s incredible that we can detect and quantify the amount of mole- cules that we know well on Earth, such as benzene, in an object that is more than 600 light-years away,” added team member Agnés Perrin of Centre National de la Recherche Scientifique in France. Next, the science team intends to ex- pand their study to a larger sample of such disks around very low-mass stars to develop their understanding of how common or exotic such car- bon-rich terrestrial planet-forming regions are. “The expansion of our study will also allow us to better understand how these molecules can form,” ex- plained team member and princi- pal investigator of the MINDS pro- gram, Thomas Henning, of the Max- Planck-Institute for Astronomy in Germany. “Several features in the Webb data are also still unidentified, so more spectroscopy is required to fully interpret our observations.” This work also highlights the crucial need for scientists to collaborate across disciplines. The team notes that these results and the accompa- nying data can contribute towards other fields including theoretical physics, chemistry, and astrochem- istry, to interpret the spectra and to investigate new features in this wavelength range. !