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arXiv · 2102.13017

Time-series and Phasecurve Photometry of Episodically-Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200 and ZTF

Josiah N. Purdum·Zhong-Yi Lin·Bryce T. Bolin·Kritti Sharma·Philip I. Choi·Varun Bhalerao·Harsh Kumar·Robert Quimby·Joannes C. Van Roestel·Chengxing Zhai·Yanga R. Fernandez·Josef Hanuš·Carey M. Lisse·Dennis Bodewits·Christoffer Fremling·Nathan Ryan Golovich·Chen-Yen Hsu·Wing-Huen Ip·Chow-Choong Ngeow·Navtej S. Saini·Michael Shao·Yuhan Yao·Tomás 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. Mróz·James D. Neill·Reed Riddle·Hector Rodriguez·Roger M. Smith·Richard Walters·Lin Yan·Jeffry Zolkower
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Abstract

We observed Episodically Active Asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and have found that it is no longer active after its recent outbursts at the end of 2018 and start of 2019. The inactivity during this apparation allowed us to measure the absolute magnitude of Gault of H_r = 14.63 +/- 0.02, G_r = 0.21 +/- 0.02 from our secular phasecurve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hours on multiple days in 2020 August, September and October. The photometric lightcurves have a repeating $\lesssim$0.05 magnitude feature suggesting that (6478) Gault has a rotation period of ~2.5 hours and may have a semi-spherical or top-like shape, much like Near-Earth Asteroids Ryugu and Bennu. The rotation period of ~2.5 hours is near to 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 spun up by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect.

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Josiah N. Purdum, Zhong-Yi Lin, Bryce T. Bolin, Kritti Sharma, Philip I. Choi, Varun Bhalerao, Harsh Kumar, Robert Quimby, Joannes C. Van Roestel, Chengxing Zhai, Yanga R. Fernandez, Josef Hanuš, Carey M. Lisse, Dennis Bodewits, Christoffer Fremling, Nathan Ryan Golovich, Chen-Yen Hsu, Wing-Huen Ip, Chow-Choong Ngeow, Navtej S. Saini, Michael Shao, Yuhan Yao, Tomás 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. Mróz, James D. Neill, Reed Riddle, Hector Rodriguez, Roger M. Smith, Richard Walters, Lin Yan, Jeffry Zolkower. 2021-02-25. Time-series and Phasecurve Photometry of Episodically-Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200 and ZTF. https://doi.org/10.3847/2041-8213/abf2ca

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