ALMA Observations Reveal Isotopic Ratios in Jupiter's Stratosphere 23 Years After Comet SL9 Impact
Researchers using the ALMA telescope measured carbon and nitrogen isotopic ratios in hydrogen cyanide (HCN) molecules in Jupiter's stratosphere, finding values that differ from earlier 1998 measurements. The measurements, taken in 2017, show enrichment in heavier isotopes relative to Jupiter's bulk composition, suggesting either a direct cometary signature or chemical evolution over 23 years. These findings help clarify the origin and composition of molecules deposited during the 1994 comet SL9 collision, a long-standing question in planetary science.
Using data from the Atacama Large Millimeter/submillimeter Array (ALMA) collected in 2017, astronomers measured isotopic ratios of carbon (12C/13C = 73±5) and nitrogen (14N/15N = 245±29) in hydrogen cyanide molecules present in Jupiter's stratosphere. These molecules were originally deposited during the 1994 collision of comet SL9 with Jupiter, which dramatically altered the planet's chemical composition. The new measurements show enrichment in heavier isotopes compared to Jupiter's bulk composition, contrasting with anomalous depletions reported in 1998 measurements. The researchers interpret these enrichments as either a direct signature of cometary material or the result of 23 years of chemical evolution in the Jovian stratosphere. This work addresses a long-standing puzzle about the origin and composition of molecules created through shock-induced chemistry when cometary and Jovian material recombined during the impacts.
What different sources said
- arXiv astro-phCenter
New 12C/13C and 14N/15N isotopic ratio measurements in Jupiter's stratosphere revealed by ALMA
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