Thermal inertia of near-Earth asteroids and implications for the magnitude of the Yarkovsky effect

By M. Delbo’, A. Dell’Oro, Alan W. Harris, Stefano Mottola, M. Mueller. 2007

231 citations recorded by the source corpus.

Abstract Thermal inertia determines the temperature distribution over the surface of an asteroid and therefore governs the magnitude the Yarkovsky effect. The latter causes gradual drifting of the orbits of km-sized asteroids and plays an important role in the delivery of near-Earth asteroids (NEAs) from the main belt and in the dynamical spreading of asteroid families. At present, very little is known about the thermal inertia of asteroids in the km size range. Here we show that the average thermal inertia of a sample of NEAs in the km-size range is 200 ± 40 J m −2 s −0.5 K −1 . Furthermore, we identify a trend of increasing thermal inertia with decreasing asteroid diameter, D . This indicates that the dependence of the drift rate of the orbital semimajor axis on the size of asteroids due to the Yarkovsky effect is a more complex function than the generally adopted D −1 dependence, and that the size distribution of objects injected by Yarkovsky-driven orbital mobility into the NEA source regions is less skewed to smaller sizes than generally assumed. We discuss how this fact may help to explain the small difference in the slope of the size distribution of km-sized NEAs and main-belt asteroids.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9a261554bbc1c876be9c7ad53d5e7356974c93d4

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

The OSIRIS‐REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations (2015, background): “This difference suggests that the particle size distribution on Itokawa is changing at the few-cm scale, and is consistent with the idea that the surface of Itokawa is deficient in particles smaller than about 3.5 cm (Miyamoto et al. 2007), compared to Bennu.”
In search of the source of asteroid (101955) Bennu: Applications of the stochastic YORP model (2015, background): “This choice implies surface thermal inertia ’150 J m 2 s 1/2 K 1, appropriate for 5–10 km asteroids (e.g., Delbò et al., 2007).”
Directional characteristics of thermal–infrared beaming from atmosphereless planetary surfaces – a new thermophysical model (2011, background): “Since thermal inertia depends predominantly on regolith particle size and depth, degree of compaction and exposure of solid rocks and boulders within the top few centimeters of the subsurface; it can be used to infer the presence or absence of loose material on the surface (Delbo’ et al. 2007).”
Near Earth Asteroids with measurable Yarkovsky effect (2012, methodology): “The rectangles correspond to reasonable values of q according to the taxonomic type and to a reasonable range of C (Delbó et al., 2007).”
Rubble Pile Asteroids (2018, background): “makes assumptions about an asteroid’s shape (spherical) to estimate an asteroid’s diameter and albedo (Harris 1998), and encodes information about thermal inertia and surface roughness in a “beaming parameter”, that can sometimes be used for comparisons of large numbers of objects (Delbó et al. 2007”
A new method to determine the grain size of planetary regolith (2012, background): “Delbo and colleagues (Delbo et al., 2007; Delbo and Tanga, 2009) compiled such results and found that an inverse correlation between the thermal inertia and the diameter of the asteroid exists.”