Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF
- 1Department of Astronomy, San Diego State University, San Diego, U.S.A.
- 2Institute of Astronomy, National Central University, Taoyuan, Taiwan
- 3IPAC, Caltech, Pasadena, U.S.A.
- 4Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, India
- 5Physics and Astronomy Department, Pomona College, Claremont, U.S.A.
- 6Department of Physics, Indian Institute of Technology Bombay, Powai, India
- 7Institute of Astronomy, Charles University, Prague, Czech Republic
- 8Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Japan
- 9Division of Physics, California Institute of Technology, Pasadena, U.S.A.
- 10Jet Propulsion Laboratory, California Institute of Technology, Pasadena, U.S.A.
- 11Deptartment of Physics and Florida Space Institute, University of Central Florida, Orlando, U.S.A.
- 12Applied Physics Laboratory, Johns Hopkins University, Laurel, U.S.A.
- 13Physics Department, Auburn University, Auburn, U.S.A.
- 14Lawrence Livermore National Laboratory, Livermore, U.S.A.
- *A full list of authors appears at the end of the abstract
We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of Hr = 14.63 ± 0.02, Gr = 0.21 ± 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault’s rotation period using timeseries photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating <0.05 mag feature suggesting that (6478) Gault has a rotation period of ∼2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of ∼2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky–O’Keefe–Radzievskii–Paddack effect.
Michael Shao, Yuhan Yao, Tomas Ahumada, Shreya Anand, Igor Andreoni, Kevin B. Burdge, Rick Burruss, Chan-Kao Chang, Chris M. Copperwheat, Michael Coughlin, Kishalay De, Richard Dekany, Alexandre Delacroix, Andrew Drake, Dmitry Duev, Matthew Graham, David Hale, Erik C. Kool, Mansi M. Kasliwal, Iva S. Kostadinova, Shrinivas R. Kulkarni, Russ R. Laher, Ashish Mahabal, Frank J. Masci, Przemyslaw J. Mroz, James D. Neill, Reed Riddle, Hector Rodriguez, Roger M. Smith, Richard Walters, Lin Yan, and Jeffry Zolkower
How to cite: Purdum, J., Lin, Z.-Y., Bolin, B., Sharma, K., Choi, P., Bhalerao, V., Hanus, J., Kumar, H., Quimby, R., Van Roestel, J., Zhai, C., Fernandez, Y., Lisse, C., Bodewits, D., Fremling, C., Golovich, N., Hsu, C.-Y., Ip, W.-H., Ngeow, C.-C., and Saini, N. and the the ZTF NEA follow-up team: Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF, European Planetary Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-409, https://doi.org/10.5194/epsc2021-409, 2021.
