65 Cybele in the thermal infrared: Multiple observations   and thermophysical
 analysis

Müller, Thomas; Blommaert, J. A. D. L.

doi:10.1051/0004-6361:20040025

Cited by 39 publications

(30 citation statements)

References 30 publications

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“…The data presented in this paper has higher S /N and spectral resolution in the 5-14 μm spectral range, and the results are consistent with those of Müller & Blommaert (2004).…”

Section: Fig 5 Emissivity Spectrum Of Cybele Compared To That Of Trsupporting

confidence: 89%

“…Thermal observations of Cybele have been published in several papers (Tedesco & Veeder 1992;Tedesco et al 2002;Morrison & Chapman 1976;Morrison 1977;Bowell et al 1979;Green et al 1985;Müller & Blommaert 2004). Müller & Blommaert (2004) analyzed all of them and using thermophysical models, derived for Cybele a size of 302 × 290 × 232 km Fig.…”

Section: Thermal Modelmentioning

confidence: 99%

“…Müller & Blommaert (2004) analyzed all of them and using thermophysical models, derived for Cybele a size of 302 × 290 × 232 km Fig. 4.…”

Section: Thermal Modelmentioning

confidence: 99%

“…The mid-infrared spectral region is also proving to be diagnostic of the surface composition of primitive asteroids, and in ways complementary to the shorter wavelengths (e.g., Cohen et al 1998;Müller & Blommaert 2004;Lim et al 2005;Emery et al 2006;Campins et al 2007). The three published midinfrared spectra, from 5 to 38 μm of Trojan asteroids (Emery et al 2006) exhibit clear emissivity features from which the compositional and physical properties can be inferred.…”

Section: Introductionmentioning

confidence: 99%

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(65) Cybele: detection of small silicate grains, water-ice, and organics

Licandro

Campins

Kelley

et al. 2010

A&A

109

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Context. (65) Cybele is the most representative member of a population of primitive asteroids in the outer edge of the main belt, the Cybele asteroids. Recent dynamical models suggest that a significant fraction of them originated in the primordial transneptunian disk, so the study of the physical properties of these asteroids is potentially a useful test of these models. Aims. Our aim is to obtain information on the surface composition of this asteroid. In particular we want to obtain information on the composition and properties of the regolith and the possible presence of ices and organic materials. Methods. We present 2-4 μm and 5-14 μm spectroscopy of (65) Cybele obtained with the NASA IRTF telescope and Spitzer Space Telescope respectively. We compare the results with spectra of Trojan asteroids and asteroid (24) Themis. We analyze the 2-4 μm spectrum using scattering models and we apply thermal models to the 5-14 μm data. Results. The 2-4 μm spectrum of (65) Cybele presents an absorption band centered at ∼3.1 μm and more weaker bands in the 3.2-3.6 μm region, very similar to those observed in (24) Themis. No hydrated silicates are detected. From the spectrum in the 5-14 μm region an effective diameter D = 290 ± 5 km, a beaming paramete η = 0.967 ± 0.014, and a geometric visible albedo p V = 0.05 ± 0.01 are derived using the NEATM thermal model. The emisivity spectrum in the 5-14 μm range exhibits an emission plateau at about 9 to 12 μm with an spectral contrast of ∼5%. This emission is similar to that of Trojan asteroids and active comets and may be due to small silicate grains being imbedded in a relatively transparent matrix, or to a very under-dense (fairy-castle) surface structure. The lower amplitude of the silicate emission in Cybele's spectrum with respect to that of Trojan asteroids could be attributed to larger dust particles and/or a slightly denser structure. Conclusions. The surface of (65) Cybele is covered by a fine anhydrous silicate grains mantle, with a small amount of water ice and complex organic solids. This is similar to comet surface where non-equilibrium phases coexist. The presence of water-ice and anhydrous silicates is indicative that hydration did not happened or is incomplete, suggesting that the temperatures were always sufficiently low.

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“…The data presented in this paper has higher S /N and spectral resolution in the 5-14 μm spectral range, and the results are consistent with those of Müller & Blommaert (2004).…”

Section: Fig 5 Emissivity Spectrum Of Cybele Compared To That Of Trsupporting

confidence: 89%

Section: Thermal Modelmentioning

confidence: 99%

“…Müller & Blommaert (2004) analyzed all of them and using thermophysical models, derived for Cybele a size of 302 × 290 × 232 km Fig. 4.…”

Section: Thermal Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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(65) Cybele: detection of small silicate grains, water-ice, and organics

Licandro

Campins

Kelley

et al. 2010

A&A

109

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“…Müller et al , 2005Müller et al , 2011aMüller et al , 2012, to main-belt asteroids (e.g. Müller & Lagerros 1998;Müller & Blommaert 2004), and also to more distant objects (e.g. Horner et al 2012;Lim et al 2010).…”

Section: Thermophysical Model Analysismentioning

confidence: 99%

Physical properties of asteroid 308635 (2005 YU₅₅) derived from multi-instrument infrared observations during a very close Earth approach

Müller¹,

Miyata²,

Kiss³

et al. 2013

A&A

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The near-Earth asteroid 308635 (2005 YU 55 ) is a potentially hazardous asteroid which was discovered in 2005 and passed Earth on Nov. 8, 2011 at 0.85 lunar distances. This was the closest known approach by an asteroid of several hundred metres in diameter since 1976 when an object of similar size passed at 0.5 lunar distances. We observed 2005 YU 55 from the ground with a recently developed mid-IR camera (miniTAO/MAX38) in N and Q bands and with the Submillimeter Array (SMA) at 1.3 mm. In addition, we obtained space observations with Herschel/PACS at 70, 100, and 160 μm. Our thermal measurements cover a wide range of wavelengths from 8.9 μm to 1.3 mm and were taken after opposition at phase angles between -97 • and -18 • . We performed a radiometric analysis via a thermophysical model and combined our derived properties with results from radar, adaptive optics, lightcurve observations, speckle, and auxiliary thermal data. We find that 308635 (2005 YU 55 ) has an almost spherical shape with an effective diameter of 300 to 312 m and a geometric albedo p V of 0.055 to 0.075. Its spin axis is oriented towards celestial directions (λ ecl , β ecl ) = (60 • ± 30 • , -60 • ± 15 • ), which means it has a retrograde sense of rotation. The analysis of all available data combined revealed a discrepancy with the radar-derived size. Our radiometric analysis of the thermal data together with the problem to find a unique rotation period might be connected to a non-principal axis rotation. A low to intermediate level of surface roughness (rms mean slope in the range 0.1-0.3) is required to explain the available thermal measurements. We found a thermal inertia in the range 350−800 Jm −2 s −0.5 K −1 , very similar to the rubble-pile asteroid 25 143 Itokawa and indicating a surface with a mixture of low conductivity fine regolith with larger rocks and boulders of high thermal inertia.

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Vesta surface thermal properties map

Capria

Tosi

Sanctis

et al. 2014

Geophysical Research Letters

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The first ever regional thermal properties map of Vesta has been derived from the temperatures retrieved by infrared data by the mission Dawn. The low average value of thermal inertia, 30 ± 10 J m À2 s À0.5 K À1, indicates a surface covered by a fine regolith. A range of thermal inertia values suggesting terrains with different physical properties has been determined. The lower thermal inertia of the regions north of the equator suggests that they are covered by an older, more processed surface. A few specific areas have higher than average thermal inertia values, indicative of a more compact material. The highest thermal inertia value has been determined on the Marcia crater, known for its pitted terrain and the presence of hydroxyl in the ejecta. Our results suggest that this type of terrain can be the result of soil compaction following the degassing of a local subsurface reservoir of volatiles.

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65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis

Cited by 39 publications

References 30 publications

(65) Cybele: detection of small silicate grains, water-ice, and organics

(65) Cybele: detection of small silicate grains, water-ice, and organics

Physical properties of asteroid 308635 (2005 YU₅₅) derived from multi-instrument infrared observations during a very close Earth approach

Vesta surface thermal properties map

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65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis

Cited by 39 publications

References 30 publications

(65) Cybele: detection of small silicate grains, water-ice, and organics

(65) Cybele: detection of small silicate grains, water-ice, and organics

Physical properties of asteroid 308635 (2005 YU55) derived from multi-instrument infrared observations during a very close Earth approach

Vesta surface thermal properties map

Contact Info

Product

Resources

About

Physical properties of asteroid 308635 (2005 YU₅₅) derived from multi-instrument infrared observations during a very close Earth approach