Physical Properties of Interstellar Comet 2I/Borisov

We are conducting an intensive program of observations of the interstellar comet 2I/Borisov using telescopes on the ground and in space. Our objectives are to characterize the body in order to make comparisons with the physical properties of solar system comets, and to monitor the effects on the nucleus of sudden exposure to the heat of our star. Results include the strongest constraints on the nucleus size, measurements of the ejected dust properties including grain size, total mass and mass production rate, and the detection of two transient split secondaries (see March 30 example in image below), interpreted as boulder explosions caused by outgassing torque spin-up. Our program continues into 2021. We will monitor the decline in activity of 2I/Borisov as the comet leaves the inner solar system and hope to observe the cessation of activity. In this video talk, we will describe the work done so far and preview measurements to come.