Databases for cometary dust characteristics

The question of whether comets contain primordial material from which the Solar System was formed or whether cometary material has already been entirely or partially processed during its evolution remains discussed [1,2,3,4,5]. The results of the studies show that the protosolar substance was chemically and physically processed according to the distance from the protostar [5,6]. Consequently, comets are a mixture of interstellar and processed material, and their initial composition might differ depending on where they formed. It is logical to compare the observed general physical properties and individual characteristics of comets with their dynamic characteristics, which determine the potential places of formation or containment of comets. Comparison of the physical characteristics of short- and long-period comets can reveal which properties of comets are original and which appeared in further evolution.

Database of comet polarimetry. The Database of Cometary Polarimetry was initiated in 2005. It aimed to catalog all available data on comets' linear and circular polarization. Based on the first version of DBCP, some observed angular and spectral characteristics of linear and circular polarization of scattered solar radiation on dust particles were analyzed to identify the main patterns in the polarization properties of cometary dust [7]. 

The second version of the database was published in 2017 [8]. It included 3416 observations for 92 comets obtained from 1881 to 2015. The second version also contains unpublished data for some comets and technical information about observation circumstances. 

Nevertheless, almost seven years have passed since the publication of the previous release, so it was necessary to update the database, supplementing it with data obtained over the past years. The updated database of cometary polarimetry allows one to study the dependences of the magnitude of the polarization of comets as a function of the phase angle, helio- and geocentric distances, and the wavelength of the transmission filter. It can also be used in theoretical modelling as an experimental basis. The updated and expanded DBCP provides more comprehensive capabilities for performing such tasks. The third database version contains more comprehensive ranges of phase angles and heliocentric and geocentric distances.

Dust activity level database. The database of Afρ values contains estimations of the Afρ parameter published in the literature. There are collected measurements for comets from various cometary families obtained at different heliocentric distances from 1977. Currently, there are about 900 measurements from about 50 papers. Primarily, there are older data, because we have been using references in source articles for our search.

The database includes the name of a comet, its perihelion distance, date of observation, helio-, geocentric distances, phase angle, orbital branch, where the comet was (pre- or post-perihelion), filter or wavelengths, which was used for measurement, pixel scale (ʺ/px), aperture size in arcseconds and kilometers, the Afρ value and its uncertainty, Gas-to-dust ratio, and references as basic information, DOI, and a link.

The primary goal of the database is to investigate whether the Afρ value reflects differences in the evolution of various cometary families. Further, we could see how this parameter changes with perihelion distance, orbital branch, and spectral range.

Acknowledgments. The research is supported by the Government Office of the Slovak Republic within NextGenerationEU programme under project No. 09I03-03-V01-00001, the Slovak Academy of Sciences (grant Vega 2/0059/22), the Slovak Research and Development Agency under the Contract no. APVV-19-0072

References

[1] Ehrenfreund, P., Charnley, S. B., and Wooden, D. 2004, in Comets II, 115

[2] Charnley, S. B. and Rodgers, S. D. 2002, The ApJ, 569, L133–L137

[3] Irvine, W. M. & Bergin, E. A. 2000, in From Molecular Clouds to Planetary, 197, 447

[4] Bockelée-Morvan, D. 2000, A&A, 353, 1101

[5] Fegley, B. 1999, SSR, 90, 239

[6] Chick, K. M. & Cassen, P. 1997, ApJ, 477, 398

[7] Kiselev, N., et al. 2005, EMP, 97, 365

[8] Kiselev, N., et al. 2017, NASA PDS, 271