http://arxiv.org/abs/1912.07386
We present high-resolution deep imaging of interstellar comet 2I/Borisov taken with the Hubble Space Telescope/Wide Field Camera 3 on 2019 October 12, 2019, November 16 and 2019 December 9 UTC (Jewitt et al. 2019). Deep image stacks of 2I on all three dates reveal no discernible signal from a nucleus suggesting that the coma is a strong component of 2I’s total sunlight scattering cross-section in the central PSF containing the nucleus of 2I effectively obscuring it despite the advanced high resolution and sensitivity of HST. We search for variations in the morphology of the coma near the central PSF and locate a possible fine jet-like structure 1-2″ in length that appears to change positions independent of the orbital velocity and anti-solar vectors over the three observation dates indicating the possibility of rotational variation of the morphology. In addition, we use deep image stacks and the non-detection of a nucleus from the highest spatial resolution HST observations available when 2I is $\sim$2 au on 2019 December 9 UTC to estimate an upper limit for the diameter of 2I’s nucleus of $\sim$1-2 km, consistent with previous high-resolution ground-based observations (Bolin et al. 2019).
B. Bolin
Tue, 17 Dec 19
40/89
Comments: 5 pages, 4 figures and 1 table, submitted to MNRAS Letters. arXiv admin note: substantial text overlap with arXiv:1910.14004