Physical Properties of Asteroids in Comet-Like Orbits in Infrared Asteroid Survey Catalogs

Abstract

We investigated the population of asteroids in comet-like orbits using available asteroid size and albedo catalogs of data taken with the Infrared Astronomical Satellite, AKARI, and the Wide-field Infrared Survey Explorer on the basis of their orbital properties (i.e., the Tisserand parameter with respect to Jupiter, T J , and the aphelion distance, Q). We found that (i) there are 123 asteroids in comet-like orbits by our criteria (i.e., Q < 4.5 AU and T J < 3), (ii) 80% of them have low albedo, p v < 0.1, consistent with comet nuclei, (iii) low-albedo objects among them have a size distribution shallower than that of active comet nuclei, that is, the power index of the cumulative size distribution of around 1.1, (iv) unexpectedly, a considerable number (i.e., 25 by our criteria) of asteroids in comet-like orbits have high albedo, p v > 0.1. We noticed that such highalbedo objects mostly consist of small (D < 3 km) bodies distributed in near-Earth space (with perihelion distance of q < 1.3 AU). We suggest that such high-albedo, small objects were susceptible to the Yarkovsky effect and drifted into comet-like orbits via chaotic resonances with planets.

Why are Jupiter-family comets active and asteroids in cometary-like orbits inactive?

“…3a in Kim et al 2014). However, for larger sizes ( 2 km in radius), the two cumulative size distributions show a significant discrepancy in slope (1.9 and 1.1, respectively).…”

“…A significant difference is already visible for sizes larger than ∼2 km in radius (see Fig. 3a in Kim et al 2014). …”

“…The similarity of the two cumulative size distributions in the small-size range indicates that ACOs and JFCs may belong to the same population of primitive bodies. Another argument for this hypothesis is given by the similarity between the Tisserand parameter of ACOs and JFCs (T J < 3; Levison & Duncan 1997;Kim et al 2014). Furthermore, ACOs and JFCs possess similar distributions of their orbital elements and, thus, of their perihelion distances (see Fig.…”

“…In comparison to comets, ACOs are inactive small bodies, but with similar orbital parameters (Fernández et al 2013;Kim et al 2014;Belton 2014). …”

“…The errors denote one standard deviation of the perihelion distances. The data were taken from the JPL Small-Body Database and the work by Kim et al (2014, their calculations have shown that the collision speeds during the collapse are low enough to not destroy the collapsing aggregates during collisons (Wahlberg Jansson & Johansen 2014;Lorek et al 2016).…”