Razvoj algoritma za ispitivanje pripadnosti asteroida familijama

Abstract

Glavni cilj ove disertacije je unapredenje pristupa identikaciji clanova familija asteroida metodom hijerarhijskog grupisanja. U proceduru se dodaje novi korak koji omogucava smanjenje tzv. lancanog efekta. Uvedeni algoritam se sastoji od cetiri glavna koraka. U prvom se primenom metode hijerarhijskog grupisanja na inicijalnom katalogu sopstvenih elemenata odreduje preliminarna lista clanova. U drugom koraku, koristeci poznate zicke karakteristike potencijalnih clanova, a na osnovu denisanih kriterijuma, identikuju se uljezi. U trecem koraku, identikovani uljezi se izbacuju iz inicijalnog kataloga sopstvenih orbitalnih elemenata cime se dobija novi, modikovani katalog. Konacno, u cetvrtom koraku ponovo se primenjuje metoda hijerarhijskog grupisanja, ali ovaj put na modikovanom katalogu sopstvenih elemenata. Pokazano je da se na ovaj nacin znacajno smanjuje broj potencijalnih uljeza u familijama asteroida. Osim toga data je kriticka analiza dobijenih rezultata, kao i detaljan prikaz nekih specicnih slucajeva. Takode, razvijen je i onlajn portal (Asteroids Families Portal; AFP) koji omogucava dostupnost ove metode siroj naucnoj zajednici. Drugi cilj disertacije je odredivanje granice za primenu metode integracije unazad, kojom se procenjuje starost mladih familija asteroida. Taj cilj je postignut upotrebom numerickih simulacija evolucije test familije. Odredivanjem trenutka grupisanja sekularnih uglova i $, ustanovljena je linearna zavisnost izmedu dubine minimuma grupisanja i starosti familije. Prema dobijenim rezultatima, metoda integracije unazad moze se uspesno primeniti na familije koje nisu starije od 18 miliona godina.

The main goal of this dissertation is improvement of an approach for identi- cation of the members of asteroid families, based on the hierarchical clustering method. An additional step is introduced in order to reduce a so-called chaining eect. The introduced algorithm consists of four main steps. In the rst step, the hierarchical clustering method is applied to the initial catalogue of proper elements in order to obtain a preliminary list of family members. In the second step, using available physical properties, and based upon the dened criteria, the interlopers are identied. In the third step, objects identied as interlopers in the second step, are excluded from the initial catalogue of proper orbital elements, producing a modied catalogue. Finally, in the fourth step, the HCM analysis is performed again, but this time using the modied catalogue of proper elements. It is shown that in this way a number of potential interlopers among family members is signicantly reduced. Moreover, an on-line based portal (Asteroids Families Portal; AFP) to apply this procedure is developed, and is freely available to all interested researchers. The second goal of the dissertation is to determine the limitations of the backward integration method, used for estimation of ages of young asteroid families. This aim is achieved through numerical simulations of the evolution of a ctitious family. By determining instants of secular angles i $ clustering, a linear relationship is found between the depth of a clustering and the age of a family. According to the obtained results, the backward integration method could be successfully applied to families not older than 18 Myrs.