A three-parameter magnitude phase function for asteroids

Muinonen, K.; Belskaya, I. N.; Cellino, A.; Delbò, M.; Levasseur-Regourd, Anny Chantal; Penttilä, Antti; Tedesco, E. F.

doi:10.1016/j.icarus.2010.04.003

Cited by 177 publications

(227 citation statements)

References 22 publications

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“…We used the value of 0.15 as the default value for the slope parameter G (Bowell et al 1989). This G value is also consistent with the published value of G ( -+ 0.12 0.03 0.04 ) for Psyche in the Asteroid Absolute Magnitude and Slope Catalog (Muinonen et al 2010;Oszkiewicz et al 2011). Figure 1(a) shows the effect of changing the beaming parameter thermal corrections in Psyche's spectra.…”

Section: Thermal Tail Removalsupporting

confidence: 89%

DETECTION OF WATER AND/OR HYDROXYL ON ASTEROID (16) Psyche

Takir

Reddy

Sanchez

et al. 2016

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In order to search for evidence of hydration on M-type asteroid (16) Psyche, we observed this object in the 3 μm spectral region using the long-wavelength cross-dispersed (LXD: 1.9-4.2 μm) mode of the SpeX spectrograph/ imager at the NASA Infrared Telescope Facility. Our observations show that Psyche exhibits a 3 μm absorption feature, attributed to water or hydroxyl. The 3 μm absorption feature is consistent with the hydration features found on the surfaces of water-rich asteroids, attributed to OH-and/or H 2 O-bearing phases (phyllosilicates). The detection of a 3 μm hydration absorption band on Psyche suggests that this asteroid may not be ametallic core, or it could be a metallic core that has been impacted by carbonaceous material over the past 4.5 Gyr. Our results also indicate rotational spectral variations, which we suggest reflect heterogeneity in the metal/silicate ratio on the surface of Psyche.

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Section: Thermal Tail Removalsupporting

confidence: 89%

DETECTION OF WATER AND/OR HYDROXYL ON ASTEROID (16) Psyche

Takir

Reddy

Sanchez

et al. 2016

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“…Using the H-G 12 conventions for sparse and low-accuracy photometric data (Muinonen et al 2010), we find H R = 19.2 mag and H V = 19.8 mag, with large uncertainties which could easily be up to one magnitude (conservative estimate based on fitting various phase functions (H-G, H-G 12 , H-G 1 -G 2 ) and taking the whole range of all possible solutions and uncertainties into account). The determination of the object's V-R colour is more reliable and based on different calculations and different data sets, we find a V-R colour of 0.56 ± 0.05 mag.…”

Section: Discussionmentioning

confidence: 99%

Large Halloween asteroid at lunar distance

Müller

Marciniak

Butkiewicz-Bąk

et al. 2017

A&A

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The near-Earth asteroid (NEA) 2015 TB 145 had a very close encounter with Earth at 1.3 lunar distances on October 31, 2015. We obtained 3-band mid-infrared observations of this asteroid with the ESO VLT-VISIR instrument covering approximately four hours in total. We also monitored the visual lightcurve during the close-encounter phase. The NEA has a (most likely) rotation period of 2.939 ± 0.005 hours and the visual lightcurve shows a peak-to-peak amplitude of approximately 0.12 ± 0.02 mag. A second rotation period of 4.779 ± 0.012 h, with an amplitude of the Fourier fit of 0.10 ± 0.02 mag, also seems compatible with the available lightcurve measurements. We estimate a V-R colour of 0.56 ± 0.05 mag from different entries in the MPC database. A reliable determination of the object's absolute magnitude was not possible. Applying different phase relations to the available R-/V-band observations produced H R = 18.6 mag (standard H-G calculations) or H R = 19.2 mag & H V = 19.8 mag (via the H-G 12 procedure for sparse and low-quality data), with large uncertainties of approximately 1 mag. We performed a detailed thermophysical model analysis by using spherical and partially also ellipsoidal shape models. The thermal properties are best explained by an equator-on (± ≈30• ) viewing geometry during our measurements with a thermal inertia in the range 250-700 Jm −2 s −0.5 K −1 (retrograde rotation) or above 500 Jm −2 s −0.5 K −1 (prograde rotation). We find that the NEA has a minimum size of approximately 625 m, a maximum size of just below 700 m, and a slightly elongated shape with a/b ≈1.1. The best match to all thermal measurements is found for: (i) Thermal inertia Γ = 900 Jm −2 s −0.5 K −1 ; D e f f = 644 m, p V = 5.5% (prograde rotation with 2.939 h); regolith grain sizes of ≈50-100 mm; (ii) thermal inertia Γ = 400 Jm −2 s −0.5 K −1 ; D e f f = 667 m, p V = 5.1% (retrograde rotation with 2.939 h); regolith grain sizes of ≈10-20 mm. A near-Earth asteroid model (NEATM) confirms an object size well above 600 m (best NEATM solution at 690 m, beaming parameter η = 1.95), significantly larger than early estimates based on radar measurements. In general, a high-quality physical and thermal characterisation of a close-encounter object from two-week apparition data is not easily possible. We give recommendations for improved observing strategies for similar events in the future.

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“…We can now also determine the bolometric Bond albedo A. The uncertainty in G translates into an uncertainty in the phase integral q (Bowell et al 1989), combined with a 5% accuracy of the q − G relation (Muinonen et al 2010), we obtain a Bond albedo of A = q · p V = 0.14 +0.03 −0.04 . Figures 7 and 8 show our best-model solution at intermediate-roughness level in different representations.…”

Section: Discussionmentioning

confidence: 99%

Thermal infrared observations of asteroid (99942) Apophis withHerschel

Müller

Kiss

Scheirich

et al. 2014

A&A

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The near-Earth asteroid (99942) Apophis is a potentially hazardous asteroid. We obtained far-infrared observations of this asteroid with the Herschel Space Observatory PACS instrument at 70, 100, and 160 μm. These were taken at two epochs in January and March 2013 during a close-Earth encounter. These first thermal measurements of Apophis were taken at similar phase angles before and after opposition. We performed a detailed thermophysical model analysis by using the spin and shape model recently derived from applying a two-period Fourier series method to a large sample of well-calibrated photometric observations. We found that the tumbling asteroid Apophis has an elongated shape with a mean diameter of 375 −0.06 . We found a thermal inertia in the range 250-800 Jm −2 s −0.5 K −1 (best solution at Γ = 600 Jm −2 s −0.5 K −1 ), which can be explained by a mixture of low-conductivity fine regolith with larger rocks and boulders of high thermal inertia on the surface. The thermal inertia, and other similarities with (25143) Itokawa indicate that Apophis might also have a rubble-pile structure. If we combine the new size value with the assumption of an Itokawa-like density and porosity we estimate a mass between 4.4 and 6.2 × 10 10 kg, which is more than 2-3 times larger than previous estimates. We expect that the newly derived properties will influence impact scenario studies and the long-term orbit predictions of Apophis.

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A three-parameter magnitude phase function for asteroids

Cited by 177 publications

References 22 publications

DETECTION OF WATER AND/OR HYDROXYL ON ASTEROID (16) Psyche

DETECTION OF WATER AND/OR HYDROXYL ON ASTEROID (16) Psyche

Large Halloween asteroid at lunar distance

Thermal infrared observations of asteroid (99942) Apophis withHerschel

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