Confirmation of the Sublimation Activity of the Primitive Main-Belt Asteroids 779 Nina, 704 Interamnia, and 145 Adeona, as well as its Probable Spectral Signs on 51 Nemausa and 65 Cybele

Abstract

This paper presents the results that confirm the sublimation activity at the perihelion of the primitive main-belt asteroids 779 Nina, 704 Interamnia, and 145 Adeona; this activity was first discovered in September 2012 (Busarev et al., 2015; Busarev et al., 2016). The new spectrophotometric and/or UBVRI photometric observations of Nina, Interamnia, and Adeona were carried out in 2016–2018 during a regular perihelion passage of these asteroids. Additionally, probable spectral signs of weak sublimation activity were discovered on another two primitive main-belt asteroids, 51 Nemausa and 65 Cybele. In this study, we discuss the conditions for the occurrence of a periodic and/or continuous sublimation process on main-belt asteroids with low-temperature mineralogy; in particular, the conditions that are associated with their formation close to the “snow line” or beyond. We also consider general evolution processes that are able sustain a sufficiently high concentration of water ice close to the surface of the bodies in question and, therefore, their continuous sublimation activity, or lead to the recurrence of extinct activity.