Dust tail observation and modeling of the interstellar comet 2I/Borisov

On 30 August 2019 the amateur Borisov discovered a new comet; after few days it was clear from the characteristics of its orbit (eccentricity > 3 and high hyperbolic excess velocity) that the second interstellar object had been detected and the object received the name of 2I/Borisov.

It appears to be very different from 1I/’Oumuamua and can be considered as the first interstellar comet.

According to the first observations the comet had a nucleus with a radius of few km and a dust coma and tail due to the activity started in June 2019 (Jewitt et al., 2019).

At the beginning of October we submitted the Discretionary Director Time (DDT) proposal to the TNG in order to monitor the comet. Some images have been acquired, in November and December 2019, with the DOLORES instrument in the R filter.

We have applied the dust model described in Fulle et al. (2010), that has been tested on the comet 67P/Churyumov-Gerasimenko and validated with the Rosetta measurements.

According to the results of our dust model and the activity model (Fulle et al., 2020) we derived a water flux from the nucleus of 8x10^-6 kg m^-2 s^-1 and a dust loss rate of 35 and 30 kg s^-1 in November and December 2019 respectively (Cremonese et al., 2020). This slight decrease has been observed around the perihelion on 8 December, few months later the comet fragmented.

In this work we will describe the dust tail observations and the dust model results, even comparing them with the Jupiter family comet 67P.

References:

G.Cremonese, et al., 2020, ApJL, 893, L12

M.Fulle et al., 2010, A&A, 522, A63.

M.Fulle et al., 2020, MNRAS, 493, 4039.

Jewitt et al., 2019, ApJ, 886, L29.