Research Division Seminar
The scattering properties of dust in distant comets

Abstract

The Oort cloud and the Edgeworth-Kuiper belt are two main reservoirs
that supply new comets to the inner region of the Solar System. Some of
the cometary nuclei demonstrate significant activity at heliocentric
distances beyond 5 au. It is of great interest to determine the reasons
for this. Since 2011 we have provided a comprehensive program of
polarimetric, photometric, and spectral investigations of active distant
comets at the 6-m telescope BTA. We present the results of broadband
polarimetric measurements for seven distant comets C/2011 S1 (LINEAR),
C/2011 R1 (LINEAR), C/2014 A4 (SONEAR), C/2013 V4 (Catalina), C/2012 J1
(Catalina), C/2011 KP36 (Spacewatch), and C/2014 B1 (Schwartz) which
have perihelion distances of more than 3 au. The comets show significant
activity beyond the Jovian orbit. Polarization maps of the comets
demonstrate spatial variations of linear polarization over the coma from
about –2% up to –7% at phase angles from 2 to 20 degrees that may be
related to changes in the physical properties of dust particles. Average
polarization values are significantly higher (in absolute values) than
the typical value of polarization (∼1.5%) observed for the whole coma of
most comets that approach closer to the Sun. Probably dust in distant
comets differs from the dust in short-period comets. We also compare the
polarimetric observational data with the results of numerical modeling
performed early for different types of dust aggregates.

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ZOOM: https://rediris.zoom.us/j/89675933678?pwd=QnptWjNYNzNZQ3V6MFl6SDdjOUFCQT09

Meeting ID: 896 7593 3678
Passcode: 334513 

YouTube: https://youtu.be/gjpr7YVmfJA