Volume 609, January 2018
|Number of page(s)||4|
|Section||Letters to the Editor|
|Published online||05 February 2018|
Letter to the Editor
Isotopic ratios in outbursting comet C/2015 ER61
European Southern Observatory,
Alonso de Còrdova 3107,
2 Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, PR China
3 Institut d’Astrophysique et de Géophysique, Université de Liège, 19c Allée du Six Août, 4000 Liège, Belgium
4 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
5 Institute of Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822, USA
Accepted: 30 November 2017
Isotopic ratios in comets are critical to understanding the origin of cometary material and the physical and chemical conditions in the early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an outburst with a total brightness increase of 2 magnitudes on the night of 2017 April 4. The sharp increase in brightness offered a rare opportunity to measure the isotopic ratios of the light elements in the coma of this comet. We obtained two high-resolution spectra of C/2015 ER61 with UVES/VLT on the nights of 2017 April 13 and 17. At the time of our observations, the comet was fading gradually following the outburst. We measured the nitrogen and carbon isotopic ratios from the CN violet (0, 0) band and found that 12C/13C = 100 ± 15, 14N/15N = 130 ± 15. In addition, we determined the 14N/15N ratio from four pairs of NH2 isotopolog lines and measured 14N/15N = 140 ± 28. The measured isotopic ratios of C/2015 ER61 do not deviate significantly from those of other comets.
Key words: comets: general / comets: individual: C/2015 ER61 (PANSTARRS) / methods: observational
© ESO, 2018
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