Puzzling M-type asteroids : unraveling their link to iron meteorites

M (metallic)-type was introduced in the 1970s to classify asteroids that were believed to be parent bodies of iron meteorites. Although M-type constitutes only about 6% of all classified asteroids, many studies were devoted to these asteroids aimed to find remnants of exposed metal cores. Intensive observations of large M-type asteroids gave numerous evidences of their diverse composition with different meteoritic analogues, including some types of enstatite and carbonaceous chondrites. Identification of asteroids with nearly pure metallic surfaces is a very challenging task. I will present the results of a dedicated study of M-type asteroids carried out in V.N. Karazin Kharkiv National University and aimed to identify potential candidates for the parent bodies of iron meteorites, evaluate their abundance and location in the asteroid belt. I will discuss the diversity of photometric and polarimetric properties of M-type asteroids and possible criteria for distinguishing metallic surfaces ; the results of searching for asteroid pairs and families among M-type objects ; determination of orbital parameters and the origin of the first iron meteoroid, whose fall was instrumentally recorded ; the distribution of M-type asteroids in the main belt, and the most accessible metal-rich near-Earth asteroids for space exploration.