The Astronomical Journal, vol. 158, no. 6, pp. 236

著者:

  • 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

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Abstract:

We report observations of a stellar occultation by the classical Kuiper Belt object (50000) Quaoar that occurred on 2019 June 28. A single-chord high-cadence (2Hz) photometry data set 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 new 1$\sigma$ and 3$\sigma$ upper limits of 6 and 16 nbar, respectively, to be set 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.