Investigation of the activity and physical properties of the active asteroids 324P/La Sagra, 2010 LH15, and 62412 (2000 SY178)

Dust emissions from asteroids are commonly attributed to the sublimation of exposed ice, which can lead to comet-like activity in main-belt comets, or to disruptions from impacts or rapid rotation, which may expose sub-surface ice for sublimation. This thesis investigates the physical and dynamical characteristics of two main-belt comets, 324P/La Sagra and 2010 LH15, as well as the disrupted asteroid 62412 (2000 SY178). For 324P/La Sagra, my research examines the temporal evolution of its activity during the 2010, 2015, and 2021 perihelion passages. A significant decline in activity was observed, potentially due to surface mantling or the depletion of volatile materials. An analysis of the Afρ profile of the coma revealed a transition near perihelion from a lower-activity pre-perihelion phase to a higher-activity steady state in the post-perihelion period. Additionally, I calculated the dust geometric albedo to range from 2% to 45%, which complicates efforts to accurately constrain the spectral type of 324P/La Sagra. Nevertheless, observations indicate evidence of dust superheating at a wavelength of 4.5 µm. A distinctive feature of 324P/La Sagra is the formation of a gap between the nucleus and its tail following the cessation of activity. The size of this gap helps constrain the dimensions of the largest ejected particles. Using the syndyne-synchrone modeling, I analyzed a faint dust trail of 324P/La Sagra captured during inactivity in 2011. This analysis indicated that the sizes of the large dust particles ranged from 0.2 mm to 0.8 mm, ejected over three months. The gas production rates were consistent with values observed for other main-belt comets, such as 238P/Read. The study of 2010 LH15 focused on its inactive nucleus, which was observed in July 2023. Photometric measurements yielded an absolute R-band magnitude of (18.4 ± 0.2) mag, corresponding to a nucleus radius of (0.5±0.1) km, assuming a C-type geometric albedo. Analysis of its lightcurve revealed no evidence of a rotational period shorter than two hours, highlighting the need for further investigation into its rotational dynamics. Lastly, this thesis explores the disrupted asteroid 62412 during its 2024 perihelion passage to determine whether it reactivated close to perihelion. Following its 2013 perihelion, 62412 displayed dust emission, likely due to rotational destabilization as a result of its fast rotation. My analysis of archival data and pre-2024 perihelion observations showed significant changes in its lightcurve amplitude and brightness post-2013, suggesting modifications in its shape and size. If confirmed, the absence of reactivation during subsequent perihelion passages may be due to a lack of exposed ice or low surface temperatures resulting from its high perihelion distance of 2.9 AU.