Video observations of tiny near-Earth objects with Tomo-e Gozen

Jin Beniyama, Shigeyuki Sako, Ryou Ohsawa, Satoshi Takita, Naoto Kobayashi, Shin Ichiro Okumura, Seitaro Urakawa, Makoto Yoshikawa, Fumihiko Usui, Fumi Yoshida, Mamoru Doi, Yuu Niino, Toshikazu Shigeyama, Masaomi Tanaka, Nozomu Tominaga, Tsutomu Aoki, Noriaki Arima, Ko Arimatsu, Toshihiro Kasuga, Sohei KondoYuki Mori, Hidenori Takahashi, Jun Ichi Watanabe

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We report the results of video observations of tiny (diameter less than 100 m) near-Earth objects (NEOs) with Tomo-e Gozen on the Kiso 105 cm Schmidt telescope. The rotational period of a tiny asteroid reflects its dynamical history and physical properties since smaller objects are sensitive to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We carried out video observations of 60 tiny NEOs at 2 fps from 2018 to 2021 and successfully derived the rotational periods and axial ratios of 32 NEOs including 13 fast rotators with rotational periods less than 60 s. The fastest rotator found during our survey is 2020 HS7 with a rotational period of 2.99 s. We statistically confirmed that there is a certain number of tiny fast rotators in the NEO population, which have been missed with all previous surveys. We have discovered that the distribution of the tiny NEOs in a diameter and rotational period (D-P) diagram is truncated around a period of 10 s. The truncation with a flat-top shape is not explained well by either a realistic tensile strength of NEOs or the suppression of YORP by meteoroid impacts. We propose that the dependence of the tangential YORP effect on the rotational period potentially explains the observed pattern in the D-P diagram.

Original languageEnglish
Pages (from-to)877-903
Number of pages27
JournalPublications of the Astronomical Society of Japan
Issue number4
Publication statusPublished - 2022 Aug 1


  • methods: observational
  • minor planets, asteroids: general
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Video observations of tiny near-Earth objects with Tomo-e Gozen'. Together they form a unique fingerprint.

Cite this