The first isotopic measurement of an exoplanet atmosphere
Isotopic variations provide important information about the origin and evolution of star and planetary systems. The isotopic ratio of carbon in carbon monoxide molecules, 12CO/13CO is roughly constant throughout the solar system, but can vary on an interstellar scale. This carbon isotopic ratio can be altered by various fractionation processes, including isotopic ion exchange reactions, ice / gas isotope separation, and selective isotopic photodissociation. A new study led by Yapeng Zhang of Leiden University in the Netherlands has reported the detection of 12CO and 13CO in the atmosphere of young super-Jupiter Tycho (TYC) 8998-760-1 b, which is the first measurement of isotopes in the atmosphere of an exoplanet.
The exoplanet TYC 8998-760-1b is 300 light years from Earth and orbits a young solar-analog star in the constellation Musca. The team observed the exoplanet using the Spectrograph for Full Field Observations in the Near Infrared (SINFONI) at the Cerro Paranal Very Large Telescope in Chile. The team focused on detecting 12CO/13CO because the spectrum of exoplanets is dominated by the molecular characteristics of carbon monoxide. The SINFONI spectra of the exoplanet TYC 8998-760-1b suggest that 13The CO in the atmosphere is significantly enriched compared to the terrestrial standard and the local interstellar value. The team postulates that because the exoplanet orbits its star well beyond the CO snow line, it formed from CO ice enriched in 13CO by fractionation, which resulted in its 13Atmosphere rich in CO. A similar mechanism has been invoked to explain the trend in the deuterium / hydrogen (D / H) ratios of Uranus and Neptune due to a contribution from the accretion of deuterium-rich ices. Analyzing isotope ratios in exoplanet atmospheres is difficult, but as telescopes improve, future measurements of exoplanet isotope ratios can provide a meaningful method for studying when, where, and how planets form. READ MORE