Pluto's atmosphere in plateau phase since 2015 from a stellar occultation at Devasthal

TL;DR

This study reports that Pluto's atmospheric pressure has remained stable since 2015, based on stellar occultation observations in 2020, supporting the plateau phase hypothesis and contrasting with other reports of pressure decrease.

Contribution

First measurement confirming Pluto's atmospheric plateau phase since 2015 using stellar occultation data from Devasthal.

Findings

Pluto's surface pressure is approximately 12.23 μbar.

Atmospheric pressure has remained stable since mid-2015.

Results agree with the volatile transport model of Meza et al. (2019).

Abstract

A stellar occultation by Pluto was observed on 6 June 2020 with the 1.3-m and 3.6-m telescopes located at Devasthal, Nainital, India, using imaging systems in the I and H bands, respectively. From this event, we derive a surface pressure for Pluto's atmosphere of $p_{\rm surf}= 12.23^{+0.65}_{-0.38} $~$\mu$bar. This shows that Pluto's atmosphere is in a plateau phase since mid-2015, a result which is in excellent agreement with the Pluto volatile transport model of Meza et al. (2019}. This value does not support the pressure decrease reported by independent teams, based on occultations observed in 2018 and 2019, see Young et al. (2021} and Arimatu et al. (2020), respectively.