New constraints on Triton's atmosphere from the 6 October 2022 stellar occultation
/ Authors
Ye Yuan, Chen Zhang, Fan Li, Jian Chen, Yan-Fei Fu, Chun-ni Bai, Xinling Gao, Yong Wang, Tuhong Zhong, Yixing Gao
and 39 more authors
Liang Wang, Donghua Chen, Yixing Zhang, Yang Zhang, Wenpeng Xie, Shupi Zhang, Ding-Jen Liu, Jun-Nan Cao, Xiangdong Yin, X. Mo, Jing Liu, Xinru Han, Tonghanyu Liu, Yuqiang Chen, Zhen-Zhen Gao, Xiang Zeng, G. Niu, Xiansheng Zheng, Yuchen Lin, Peiyu Ye, W. Liang, Chengcheng Zhu, Zhi-Qiang Hu, Jian-Xia He, Wei Zhang, Yue Chen, Zhu Cheng, Tianrui Sun, Chen-shuo Guo, Yue Lu, Jiajun Lin, Wei Tan, Jia Zhou, Jun Xu, Jun He, Jiahui Ye, Delai Li, Shuai Zhang, Qing Qu
/ Abstract
The atmosphere of Triton was probed directly by observing a ground-based stellar occultation on 6 October 2022. This rare event yielded 23 positive light curves collected from 13 separate observation stations contributing to our campaign. The significance of this event lies in its potential to directly validate the modest pressure fluctuation on Triton, a phenomenon not definitively verified by previous observations, including only five stellar occultations, and the Voyager 2 radio occultation in 1989. Using an approach consistent with a comparable study, we precisely determined a surface pressure of $14.07_ in 2022. This new pressure rules out any significant monotonic variation in pressure between 2017 and 2022 through direct observations, as it is in alignment with the 2017 value. Additionally, both the pressures in 2017 and 2022 align with the 1989 value. This provides further support for the conclusion drawn from the previous volatile transport model simulation, which is consistent with the observed alignment between the pressures in 1989 and 2017; that is to say, the pressure fluctuation is modest. Moreover, this conclusion suggests the existence of a northern polar cap extended down to at least $45 and the presence of nitrogen between $30 and $0
Journal: Astronomy & Astrophysics