Interferometric Imaging of Titan’s HC 3 N, H 13 CCCN, and HCCC 15 N

• Published in: The Astrophysical Journal
• Main Authors: Cordiner, M. A., Nixon, C. A., Charnley, S. B., Teanby, N. A., Molter, E. M., Kisiel, Z., Vuitton, V.
• Other Authors: Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: planets and satellites: atmospheres; planets and satellites: individual: Titan; submillimeter: planetary systems; techniques: imaging spectroscopy; techniques: interferometric; Astrophysics - Earth and Planetary Astrophysics; [SDU]Sciences of the Universe [physics]; North Pole; South Pole; South pole
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03693561; https://doi.org/10.3847/2041-8213/aac38d

International audience We present the first maps of cyanoacetylene isotopologues in Titan’s atmosphere, including H 13 CCCN and HCCC 15 N, detected in the 0.9 mm band using the Atacama Large Millimeter/submillimeter array (ALMA) around the time of Titan’s (southern winter) solstice in 2017 May. The first high-resolution map of HC 3 N in its v 7 = 1 vibrationally excited state is also presented, revealing a unique snapshot of the global HC 3 N distribution, free from the strong optical depth effects that adversely impact the ground-state (v = 0) map. The HC 3 N emission is found to be strongly enhanced over Titan’s south pole (by a factor of 5.7 compared to the north pole), consistent with rapid photochemical loss of HC 3 N from the summer hemisphere combined with production and transport to the winter pole since the 2015 April ALMA observations. The H 13 CCCN/HCCC 15 N flux ratio is derived at the southern HC 3 N peak, and implies an HC 3 N/HCCC 15 N ratio of 67 ± 14. This represents a significant enrichment in 15 N compared with Titan’s main molecular nitrogen reservoir, which has a 14 N/ 15 N ratio of 167, and confirms the importance of photochemistry in determining the nitrogen isotopic ratio in Titan’s organic inventory.