Spitzer observations of the asteroid-comet transition object and potential spacecraft target 107P (4015) Wilson-Harrington

Abstract

Context. Near-Earth asteroid-comet transition object 107P/ (4015) Wilson-Harrington is a possible target of the joint European Space Agency (ESA) and Japanese Aerospace Exploration Agency (JAXA) Marco Polo sample return mission. Physical studies of this object are relevant to this mission, and also to understanding its asteroidal or cometary nature. Aims. Our aim is to obtain significant new constraints on the surface thermal properties of this object. Methods. We present mid-infrared photometry in two filters (16 and 22 μm) obtained with NASA's Spitzer Space Telescope on February 12, 2007, and results from the application of the Near Earth Asteroid Thermal Model (NEATM). We obtained high S/N in two mid-IR bands allowing accurate measurements of its thermal emission. Results. We obtain a well constrained beaming parameter (η = 1.39 ± 0.26) and obtain a diameter and geometric albedo of D = 3.46 ± 0.32 km, and p V = 0.059 ± 0.011. We also obtain similar results when we apply this best-fitting thermal model to single-band mid-IR photometry reported by Campins et al. (1995, P&SS, 43, 733), Kraemer et al. (2005, AJ, 130, 2363 and Reach et al. (2007, Icarus, 191, 298). Conclusions. The albedo of 4015 Wilson-Harrington is low, consistent with those of comet nuclei and primitive C-, P-, D-type asteorids. We establish a rough lower limit for the thermal inertia of W-H of 60 Jm −2 s −0.5 K −1 when it is at r = 1 AU, which is slightly over the limit of 30 Jm −2 s −0.5 K −1 derived by Groussin et al. (2009, Icarus, 199, 568) for the thermal inertia of the nucleus of comet 22P/Kopff.

Thermal Modeling of Comet-like Objects from AKARI Observation

“…DeMeo & Carry (2013) found that 833 Btype asteroids have an average p V = 0.071 ± 0.033 (Table 4 of their paper), which is consistent with our result (p V = 0.04-0.055). Additionally, the size and albedo derived from our TPM is consistent with those of Spitzer Space Telescope infrared and ground based photometric observations: p V = 0.059 ± 0.011, D = 3.46 ± 0.32 km from Licandro et al (2009) and p R = 0.055 ± 0.012, D = 3.63 ± 0.56 km from Ishiguro et al (2011). The thermal inertia we obtained (Γ = 100-250 SI) is also consistent with the lower bound (60 SI) set by Licandro et al (2009).…”

“…Additionally, the size and albedo derived from our TPM is consistent with those of Spitzer Space Telescope infrared and ground based photometric observations: p V = 0.059 ± 0.011, D = 3.46 ± 0.32 km from Licandro et al (2009) and p R = 0.055 ± 0.012, D = 3.63 ± 0.56 km from Ishiguro et al (2011). The thermal inertia we obtained (Γ = 100-250 SI) is also consistent with the lower bound (60 SI) set by Licandro et al (2009). These facts indicate that the model assumptions in Section 3 produce reliable results to some extent.…”

“…∼ 4 %, Bottke et al 2002). A detailed investigation using Spitzer Space Telescope has also been conducted applying NEATM (Licandro et al 2009). They derived D = 3.46 ± 0.32 km, p V = 0.059 ± 0.011, and η = 1.39 ± 0.26).…”

Thermal properties, sizes, and size distribution of Jupiter-family cometary nuclei

“…The survey we present here represents the first systematic investigation of thermal inertia across a large number -dozens -of comets. Some results on individual nuclei in our survey have appeared already (Groussin et al 2009, Licandro et al 2009. In this paper we present results for all of the survey's sample, and also present the distributions of JFC nucleus size and thermal behavior.…”

The Active Asteroids

“…Spectral observations limited the production of the CN radical to Q CN 1.4 × 10 23 s −1 , again corresponding to a water production rate 1.5 kg s −1 assuming H 2 O/CN = 360. P/2008 R1 is located near the 8:3 mean-motion resonance Hsieh et al 2004Hsieh et al , 2009aHsieh et al , 2011b(8) Hsieh et al 2012;Licandro et al 2011;(9) Hsieh et al 2011c; (10) Moreno et al 2011a;Hsieh et al 2012;(11) Veeder et al 1984;Fernández et al 1997;Licandro et al 2009;Urakawa et al 2011. with Jupiter and is also affected by the ν 6 secular resonance. The dynamical lifetime in this orbit is short (20-30 Myr) compared with the age of the solar system, suggesting that P/2008 R1 was scattered into its present location from elsewhere in the asteroid belt.…”