Low Perihelion Near-Earth Asteroids

Campins, H.; Kelley, Michael S. P.; Fernández, Yanga; Licandro, J.; Hargrove, K.

doi:10.1007/s11038-009-9310-2

Cited by 19 publications

(21 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values of η derived for asteroid 162173 using the NEATM fits to our spectrum are given in Table 1; for all our thermal models we assumed a bolometric emissivity ( ) of 0.9. These η values can be compared with those of other asteroids studied in a similar manner, and in fact fit well the trend of increasing η (lower thermal fluxes and cooler color temperatures) with increasing solar phase angle, observed for about 40 nearEarth asteroids so far (e.g., Delbó 2004;Campins et al 2009). We did not make any observations of this asteroid's reflected continuum, so to estimate the geometric albedo (p V ), we adopted the values given by Hasegawa et al (2008) of H V = 18.81 ± 0.03 and G = −0.115 ± 0.009, where H V is the visible absolute magnitude and G is the slope parameter.…”

Section: Thermal Modelingsupporting

confidence: 83%

Spitzer observations of spacecraft target 162173 (1999 JU3)

Campins

Emery

Kelley

et al. 2009

A&A

View full text Add to dashboard Cite

Context. Near-Earth asteroid 162173 (1999 JU3) is the primary target of the Japanese Aerospace Exploration Agency (JAXA) Hayabusa-2 sample return mission, and is also on the list of potential targets for the European Space Agency (ESA) Marco Polo sample return mission. Earth-based studies of this object are fundamental to these missions. Aims. Our aim is to provide new constraints on the surface properties of this asteroid. Methods. We present a mid-infrared spectrum (5-38 μm) obtained with NASA's Spitzer Space Telescope in May 2008 and results from the application of thermal models. Results. These observations place new constraints on the surface properties of this asteroid. To fit our spectrum we used the near-Earth asteroid thermal model (NEATM) and the more complex thermophysical model (TPM). However, the position of the spin-pole, which is uncertain, is a crucial input parameter for constraining the thermal inertia with the TPM; hence, we consider two pole orientations. First is the extreme case of an equatorial retrograde geometry from which we derive a rigorous lower limit to the thermal inertia of 150 Jm −2 s −0.5 K −1 . Second, when we adopt the pole orientation of Abe et al. (2008a, 37 th COSPAR Scientific Assembly) our best-fit thermal model yields a value for the thermal inertia of 700 ± 200 Jm −2 s −0.5 K −1 and even higher values are allowed by the uncertainty in the spectral shape due to the absolute flux calibration. Our best estimates of the diameter (0.90 ± 0.14 km) and geometric albedo (0.07 ± 0.01) of asteroid 162173 are consistent with values based on previous mid-infrared observations. Conclusions. We establish a rigorous lower limit to the thermal inertia, which is unlikely but possible, and would be consistent with a fine regolith similar to wthat is found for asteroid 433 Eros. However, the thermal inertia is expected to be higher, possibly similar to or greater than that on asteroid 25143 Itokawa. An Accurately determining the spin-pole of asteroid 162173 will narrow the range of possible values for its thermal inertia.

show abstract

Section: Thermal Modelingsupporting

confidence: 83%

Spitzer observations of spacecraft target 162173 (1999 JU3)

Campins

Emery

Kelley

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…While their D and p V are consistent with ours, their η value is smaller. Their observations were done at a much higher phase angle, so this doesnot fit well with the trend of increasing η with increasing solar phase angle that has been observed for about 40 near-Earth asteroids so far (e.g., Delbó 2004;Campins et al 2009). However according to Kraemer (personal communication) they did not use the 14.7 μm flux to derive their reported D and p V as they concluded that this flux was poorly constrained.…”

Section: Discussionmentioning

confidence: 87%

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

Licandro

Campins

Kelley

et al. 2009

A&A

View full text Add to dashboard Cite

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.

show abstract

“…As of 2017 October, JPL Horizons lists 39 asteroids with perihelia within the sunskirter region of < 0.15 AU (33.1 R ). Subsets of these have been reviewed by Campins et al (2009) andJewitt (2013), although in both cases the authors generally considered objects with q significantly beyond 0.15 AU, so the results may not be applicable to objects observed by SOHO and/or STEREO.…”

Section: Near-sun Asteroidsmentioning

confidence: 99%

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

et al. 2017

View full text Add to dashboard Cite

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all ob- jects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun's centre, equal to half of Mercury's perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground-and space-based facilities that will allow us to address those science topics.

show abstract

Low Perihelion Near-Earth Asteroids

Cited by 19 publications

References 10 publications

Spitzer observations of spacecraft target 162173 (1999 JU3)

Spitzer observations of spacecraft target 162173 (1999 JU3)

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

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

Contact Info

Product

Resources

About