New constraint on the atmosphere of (50000) Quaoar from a stellar occultation

Ko Arimatsu; Ryou Ohsawa; George L. Hashimoto; Seitaro Urakawa; Jun Takahashi; Miyako Tozuka; Yoichi Itoh; Misato Yamashita; Fumihiko Usui; Tsutomu Aoki; Noriaki Arima; Mamoru Doi; Makoto Ichiki; Shiro Ikeda; Yoshifusa Ita; Toshihiro Kasuga; Naoto Kobayashi; Mitsuru Kokubo; Masahiro Konishi; Hiroyuki Maehara; Noriyuki Matsunaga; Takashi Miyata; Mikio Morii; Tomoki Morokuma; Kentaro Motohara; Yoshikazu Nakada; Shin-ichiro Okumura; Shigeyuki Sako; Yuki Sarugaku; Mikiya Sato; Toshikazu Shigeyama; Takao Soyano; Hidenori Takahashi; Ken'ichi Tarusawa; Nozomu Tominaga; Jun-ichi Watanabe; Takuya Yamashita; Makoto Yoshikawa

doi:10.3847/1538-3881/ab5058

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arXiv · 1910.09988

New constraint on the atmosphere of (50000) Quaoar from a stellar occultation

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Abstract

We report observations of a stellar occultation by the classical Kuiper belt object (50000) Quaoar occurred on 28 June 2019. A single-chord high-cadence (2 Hz) photometry dataset was obtained with the Tomo-e Gozen CMOS camera mounted on the 1.05 m Schmidt telescope at Kiso Observatory. The obtained ingress and egress data do not show any indication of atmospheric refraction and allow to set new $1\sigma$ and $3\sigma$ upper limits of 6 and 16 nbar, respectively, for the surface pressure of a pure methane atmosphere. These upper limits are lower than the saturation vapor pressure of methane at Quaoar's expected mean surface temperature ($T \sim 44$ K) and imply the absence of a $\sim$10 nbar-level global atmosphere formed by methane ice on Quaoar's surface.

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Ko Arimatsu, Ryou Ohsawa, George L. Hashimoto, Seitaro Urakawa, Jun Takahashi, Miyako Tozuka, Yoichi Itoh, Misato Yamashita, Fumihiko Usui, Tsutomu Aoki, Noriaki Arima, Mamoru Doi, Makoto Ichiki, Shiro Ikeda, Yoshifusa Ita, Toshihiro Kasuga, Naoto Kobayashi, Mitsuru Kokubo, Masahiro Konishi, Hiroyuki Maehara, Noriyuki Matsunaga, Takashi Miyata, Mikio Morii, Tomoki Morokuma, Kentaro Motohara, Yoshikazu Nakada, Shin-ichiro Okumura, Shigeyuki Sako, Yuki Sarugaku, Mikiya Sato, Toshikazu Shigeyama, Takao Soyano, Hidenori Takahashi, Ken'ichi Tarusawa, Nozomu Tominaga, Jun-ichi Watanabe, Takuya Yamashita, Makoto Yoshikawa. 2019-10-22. New constraint on the atmosphere of (50000) Quaoar from a stellar occultation. https://doi.org/10.3847/1538-3881%2Fab5058

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