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Session: Stars, Planets and the Interstellar Medium

Name: Mr. Dimitrios Athanasopoulos (National & Kapodistrian Univ. of Athens)
Coauthors: Gazeas Kosmas (NKUA)
Avdellidou Chrysa (University of Leiceste)
Hanus Josef (Charles University)
van Belle Gerard (Lowell Observatory)
Ferrero Andrea (Bigmuskie Observatory)
Bonamico Roberto (BSA Observatory)
Delbo Marco (OCA)
Rivet Jean-Pierre (OCA)
Conjat Matthieu (OCA)
Apostolovska Gordana (Ss. Cyril and Methodius University in Skopje)
Todorović Nataša (Belgrade Astronomical Observatory)
Bebekovska Elena Vchkova (Ss. Cyril and Methodius University in Skopje)
Novakovic Bojan (University of Belgrade)
Sioulas Nick (NOAK Observatory)
Type: Oral
Title: Ancient Asteroids: An observing campaign reveals the spin states of asteroids that belong to the most ancient collisional families of our Solar System
Abstract:

The first moments of our Solar System are determined by the gas phase of the protoplanetary disk, where the first ~100 kilometer-size solid bodies, the planetesimals, were formed. Only a few of them accreted by mutual collisions or enough mass via pebble accretion to form planets, the rest of them were removed during the violent phases of planetary migration and instability, while a few leftover are still present today in the solar system as dwarf planets or even smaller bodies. The small bodies of the inner Solar System formed an asteroid belt, whose original state is a crucial problem of planetary science. In the Main Asteroid Belt, the new asteroids stay relatively close (in terms of orbital element space) to the parent asteroid as a result to form clusters in it, the so-called asteroid collisional families. Traditional identification methods, like Hierarchical Clustering Methods, are unable to recognise Gyr- and older asteroid families, whose the family members are very dispersed by the Yarkovsky effect. A novel technique takes the advantage of the diurnal searching for the signature of the size dependent dispersion of family members operated by the Yarkovsky effect, in order to identify the most ancient collisional families of the Solar System. The method has already successfully identified two primordial families which likely formed before the giant planet orbital instability and could be as old as the Solar System and an ancient one that is ~3 Gyr-old. There is evidence from observations and theoretical evolution models that there are more old families to be. The reliability of these V-shape families has been independently tested. The observing campaign “Ancient Asteroids” initiated a Pro-Am collaboration in order to collect photometric observations for the members of these families. The obtained lightcurves from all the involved participants will be combined with data available in the literature, as well as with sparse data from space missions (Gaia, TESS, etc) and global sky surveys (ZTF, ATLAS, ASAS-SN, etc). The observations revealed the spin state of the members verifying their family membership. Further analysis of these data shown the evolutional characteristics of these collisional families, leading to a better understanding of the first stages of the evolution of the asteroid belt and the Solar System.