Constraints on Triton atmospheric evolution from occultations: 1989-2022

• DOI: 10.48550/arxiv.2402.02476
• Publication Date: 2024-02-04
• Authors: B. Sicardy; Anandmayee Tej; A. R. Gomes-Júnior; F. D. Romanov; Tanguy Bertrand; N. M. Ashok; E. Lellouch; B. E. Morgado; M. Assafin; J. Desmars; J. I. B. Camargo; Y. Kılıç; J. L. Ortiz; R. Vieira-Martins; F. Braga-Ribas; Joe P. Ninan; B. C. Bhatt; S. Kumar; V. Swain; Sanjib Sharma; Abhijit Saha; D. K. Ojha; G. Pawar; S. Deshmukh; ADITYA DESHPANDE; S. Ganesh; J. K. Jain; Shibu K. Mathew; Harsh Kumar; V. Bhalerao; G. C. Anupama; Sudhanshu Barway; A. Brandeker; H.-G. Florén; G. Olofsson; G. Bruno; Y. M. Mao; Rong Ye; Q. Y. Zou; Yuhang Sun; Y. Y. Shen; Jing Zhao; D. N. Grishin; L. V. Romanova; Franck Marchis; Keiichi Fukui; R. Kukita; G. Benedetti-Rossi; P. Santos-Sanz; Neha Dhyani; A.M. Gokhale; Anahita Kate

Context - Around the year 2000, Triton's south pole experienced an extreme summer solstice that occurs every about 650 years, when subsolar latitude reached 50{\deg}. Bracketing this epoch, a few occultations probed atmosphere in 1989, 1995, 1997, 2008 and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides new measurement of atmospheric pressure which is presented here. Aims- The goal to constrain Volatile Transport Models (VTMs) basically vapor equilibrium with nitrogen ice at its surface. Methods Fits light curves yield reference radius 1400 km, from surface induced. Results fits provide p_1400= 1.211 +/- 0.039 microbar km (47 altitude), p_surf= 14.54 0.47 induced (1-sigma error bars). To within bars, identical derived previous 5 2017, p_1400 = 1.18 0.03 14.1 0.4 microbar, respectively. Based models volatile cycles, overall evolution over last 30 years consistent N2 condensation taking place northern hemisphere. However, typically predict steady decrease for period 2005-2060, not confirmed by observation. Complex surface-atmosphere interactions, such as albedo runaway formation local frosts equatorial regions Triton could explain relatively constant between 2017 2022.