Galileo Observations of Europa's Opposition Effect

Helfenstein, P.; Currier, N.; Clark, B. E.; Veverka, J.; Bell, Maureen; Sullivan, Robert; Klemaszewski, J. E.; Greeley, R.; Pappalardo, R.; Head, J. W.; Jones, Todd J.; Klaasen, K. P.; Magee, K. P.; Geissler, P. E.; Greenberg, R.; McEwen, A. S.; Phillips, C. B.; Colvin, T. R.; Davies, Merton E.; Denk, T.; Neukum, G.; Belton, M. J. S.

doi:10.1006/icar.1998.5975

Cited by 70 publications

(35 citation statements)

References 38 publications

(7 reference statements)

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“…Other objects show opposite or even nonmonotonic relations between phase function slope and wavelength. For instance, some types of terrain on the Jovian moon Europa have phase functions that vary nonmonotonically with wavelength (Helfenstein et al 1998), while Pluto's phase function has a weak wavelength dependence opposite to that seen in Haumea, from β B = 0.037±0.001 mag deg −1 to β R = 0.032 ± 0.001 mag deg −1 (Buratti et al 2003).…”

Section: Phase Functionmentioning

confidence: 99%

Time-Resolved Near-Infrared Photometry of Extreme Kuiper Belt Object Haumea

Lacerda

2009

The Astronomical Journal

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We present time-resolved near-infrared (J and H) photometry of the extreme Kuiper belt object (136108) Haumea (formerly 2003 EL61) taken to further investigate rotational variability of this object. The new data show that the near-infrared peak-to-peak photometric range is similar to the value at visible wavelengths, Δm R = 0.30 ± 0.02 mag. Detailed analysis of the new and previous data reveals subtle visible/near-infrared color variations across the surface of Haumea. The color variations are spatially correlated with a previously identified surface region, redder in B − R and darker than the mean surface. Our photometry indicates that the J − H colors of Haumea (J − H = −0.057 ± 0.016 mag) and its brightest satellite Hi'iaka (J − H = −0.399 ± 0.034 mag) are significantly (greater than 9σ ) different. The satellite Hi'iaka is unusually blue in J −H , consistent with strong 1.5 μm water-ice absorption. The phase coefficient of Haumea is found to increase monotonically with wavelength in the range 0.4 < λ < 1.3. We compare our findings with other solar system objects and discuss implications regarding the surface of Haumea.

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Section: Phase Functionmentioning

confidence: 99%

Time-Resolved Near-Infrared Photometry of Extreme Kuiper Belt Object Haumea

Lacerda

2009

The Astronomical Journal

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“…In principle, the difference can be due to imperfection of the approximation (20) [Pohn et al, 1969[Pohn et al, , 1971, that of Mars with Viking data [Thorpe, 1982], and that of Jovian satellite Europa with Galileo data [Helfenstein et al, 1998]. In this section we consider different methods to study the lunar opposition effect using Clementine image data.…”

Section: Opposition Effectmentioning

confidence: 99%

Photometric properties of the lunar surface derived from Clementine observations

Kreslavsky¹,

Shkuratov²,

Velikodsky³

et al. 2000

J. Geophys. Res.

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Abstract. Photometric properties of the lunar surface in visual and near-infrared light were studied using raw images obtained with UVVIS camera during the Clementine mission. The investigation focused on several specific regions on the lunar surface, each of which was observed by Clementine at a variety of different illumination and viewing geometries. Through these observations, the dependence of the surface brightness on the observation/illumination geometry was studied. It was shown that the disk component of this dependence, that is, the variations of brightness at constant phase angle, is different for different mare areas. The color of the lunar surface also changes with changing of the observation/illumination geometry, even if under constant phase angle. The Reiner Gamma formation displays unusual photometric properties. They are consistent with the surface being smoother than the typical mare regolith surface. The UVVIS images taken at the smallest phase angles were used to study the opposition spike, that is, the sharp increase of the surface brightness near the opposition. Steepness of the phase dependence of brightness varies over a wide range for different sites.

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“…Two causes to give rise to the opposition effect are usually considered: (1) shadow-hiding and (2) interference-enhancement, often called coherent-backscatter. Some general regolith properties-dependent characteristics of each mechanism are understood, and some papers are devoted to a discussion on the relative contribution of both mechanisms (Drossart 1993;Helfenstein et al 1997Helfenstein et al , 1998Hapke et al 1998;Nelson et al 2000;Belskaya & Shevchenko 2000;Shkuratov & Helfenstein 2001;Poulet et al 2002). One can check for the effect of coherent backscatter and/or shadow hiding by studying the influence of wavelength of incident light on the opposition brigthening.…”

Section: Introductionmentioning

confidence: 99%

Photometry of the Kuiper-Belt object 1999 TD$_{\sf\sl 10}$ at different phase angles

Rousselot

Petit

Poulet

et al. 2003

A&A

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Abstract. We present photometric observations of the Kuiper-Belt object 1999 TD 10 at different phase angles and for three different broad band filters (B, V and R). This object was observed with the Danish 1.54-m telescope of ESO in Chile during six different observing nights corresponding to a phase angle of 0. 30, 0.37, 0.92, 3.43, 3.48 and 3.66 • . Extra observations were obtained in September 2002 with the VLT UT1/FORS1 combination to confirm that 1999 TD 10 does not exhibit any cometary activity, and in October 2001 with the Sierra Nevada Observatory 1.50-m telescope in order to add relative magnitudes to improve the determination of the rotation period. The observations are compatible with a single-peaked rotational lightcurve with a 7h41.5min ± 0.1 min period or a doublepeaked lightcurve with a 15h22.9min ± 0.1 min period. If a single-peaked rotational lightcurve is assumed the amplitude is 0.51 ± 0.03, 0.49 ± 0.05 and 0.60 ± 0.09 mag for the R, V and B bands, respectively. We present the phase curve obtained when assuming that the lightcurve is single-peaked. This phase curve reveals clearly an increase of about 0.3 mag and of similar importance for the three bands when phase angle decreases from 3.7 • to 0.3 • . The phase curve reveals a linear increase of the brightness with the decreasing phase angle and, consequently, does not permit a modeling of the opposition surge. Neverthless the poor repartition of the observational data does not permit a firm conclusion concerning the presence or absence of an opposition surge on the phase angle range covered by our data. Complementary observations are needed.

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Galileo Observations of Europa's Opposition Effect

Cited by 70 publications

References 38 publications

Time-Resolved Near-Infrared Photometry of Extreme Kuiper Belt Object Haumea

Time-Resolved Near-Infrared Photometry of Extreme Kuiper Belt Object Haumea

Photometric properties of the lunar surface derived from Clementine observations

Photometry of the Kuiper-Belt object 1999 TD$_{\sf\sl 10}$ at different phase angles

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