In order to look for large super-fast rotators, in late 2014 and early 2015, five dedicated surveys covering ̃188 deg2 in the ecliptic plane have been carried out in the R-band, with ̃10 minute cadence using the intermediate Palomar Transient Factory. Among 1029 reliable rotation periods obtained from the surveys, we discovered 1 new large super-fast rotator, (40511) 1999 RE88, and 18 other candidates. (40511) 1999 RE88 is an S-type inner main-belt asteroid with a diameter of D = 1.9 ± 0.3 km, a rotation period of P = 1.96 ± 0.01 hr, and a light curve amplitude of ∆m ̃ 1.0 mag. To maintain such fast rotation, an internal cohesive strength of ̃780 Pa is required. Combining all known large super-fast rotators, their cohesive strengths all fall in the range of 100-1000 Pa of lunar regolith. However, the number of large super-fast rotators seems to be far less than the whole asteroid population. This might indicate a peculiar asteroid group for them. Although the detection efficiency for a long rotation period is greatly reduced due to our two-day observation time span, the spin-rate distributions of this work show consistent results with Chang et al. (2015), after considering the possible observational bias in our surveys. It shows a number decrease with an increase of spin rate for asteroids with a diameter of 3 ⩽ D ⩽ 15 km, and a number drop at a spin rate of f = 5 rev day-1 for asteroids with D ⩽ 3 km.
The Astrophysical Journal Supplement Series
- Pub Date:
- December 2016
- minor planets;
- asteroids: general;
- Astrophysics - Earth and Planetary Astrophysics
- Accepted by ApJS in Aug 2016. 33 pages (not include the full tables and figures). The full tables and figures for asteroid rotation periods will be available when the paper is officially published on ApJS