Photopolarimetric Modelling of Cometary Dust
Lead Research Organisation:
University College London
Department Name: Physics and Astronomy
Abstract
The subject of the PhD research will be to carry out modelling of photopolarimetric data of comets, with the aim of recovering the structure and composition of the dust ejecta. The modelling results will be linked to the general properties of the solar system and models of its formation. The modelling is performed by adapting and using the multi-sphere T-matrix code (Mackowski, D W & Mishchenko, M I 2011, "A multiple sphere T-matrix Fortran code for use on parallel computer clusters", Journal of Quantitative Spectroscopy and Radiative Transfer, 122(13), 2182-2192). The output of this code will be compared with colour maps, polarimetric maps, and spectropolarimetric data of comet 67P, which were obtained during extensive campaings at the ESO VLT and at the ING WTH.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/N503927/1 | 19/10/2015 | 18/04/2021 | |||
| 1822035 | Studentship | ST/N503927/1 | 19/10/2015 | 18/09/2020 | Rok Nezic |
| Description | "PhD careers: the options" event travel grant |
| Amount | £178 (GBP) |
| Organisation | Science and Technologies Facilities Council (STFC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 10/2016 |
| End | 10/2016 |
| Description | ELS XVI Conference fee waiver & travel grant |
| Amount | $1,400 (USD) |
| Organisation | Department of Defense |
| Sector | Public |
| Country | United States |
| Start | 01/2017 |
| End | 04/2017 |
| Description | EPSC 2018 Conference fee waiver & travel grant |
| Amount | € 450 (EUR) |
| Organisation | Europlanet |
| Sector | Charity/Non Profit |
| Country | France |
| Start | 06/2018 |
| End | 09/2018 |
| Description | RAS Small Grant Award |
| Amount | £750 (GBP) |
| Organisation | Royal Astronomical Society |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 11/2016 |
| End | 04/2017 |
| Description | Rosetta Workshop (Graz 2016) travel grant |
| Amount | £235 (GBP) |
| Organisation | Europlanet |
| Sector | Charity/Non Profit |
| Country | France |
| Start | 07/2016 |
| End | 07/2016 |
| Description | SAMCSS 2017 summer school application & travel grant |
| Amount | £150 (GBP) |
| Organisation | Science and Technologies Facilities Council (STFC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 05/2017 |
| End | 08/2017 |
| Title | COMINTPOL image analysis routine |
| Description | COMINTPOL ('comet data from integrative analysis of polarimetric imagery') is a comprehensive image analysis routine written in IDL for extracting polarimetric information from a number of observatories in a semi-automatic manner. Focused particularly on STEREO ('Solar Terrestrial Relations Observatory') coronagraph data, this tool takes a series of polarimetric images as input, locates the comet within them with aid of known orbital parameters of the comet and known position of the observatory (spacecraft), determines the location and extent of comet tail, collapses the polarised intensity information of the tail into a 1-dimensional vector along the tail, and then combines the different polarimetric images in order to extract the Stokes parameters on total intensity and linear polarisation of the comet. This process is automatically repeated for the duration of observations of the comet in the imagery. In the end, a variety of plots for easier data analysis and presentation can be created with the same tool. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2019 |
| Provided To Others? | No |
| Impact | This tool was used as the core for the second half of my thesis work, where a number of observations of near-Sun comets have been analysed with it. The results showed a prevalence of polarimetric properties not seen in any observations of other comet groups. The conclusions drawn from the detailed analysis show, on the one hand, evidence of change in properties of the cometary dust (as interpreted from polarimetric signatures) consistent with the heating experienced in the near-Sun environment. For some of the comets, outbursts were observed as well, indicating a phase transition of refractory material in close proximity to the Sun (and therefore high temperatures). This work helps us better understand both the effects of the near-Sun environment on Small Solar System Bodies and the more detailed structural and compositional properties of cometary dust, as sampled by the changing polarimetric properties. |