Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

Grundy, W. M.; Olkin, C. B.; Young, L. A.; Buie, M. W.; Young, E. F.

doi:10.1016/j.icarus.2013.01.019

Cited by 73 publications

(44 citation statements)

References 67 publications

(122 reference statements)

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“…The minimum of the shifts corresponds to a region where the abundance of methane is higher (the Charon-facing hemisphere). This could indicate a higher degree of saturation of CH 4 in this hemisphere (Tegler et al 2012;Grundy et al 2013;Trafton 2015). Our measurements in the visible show the same trend as do the estimates from the NIR observations, apparently indicating that the degree of dilution is uniform over different path lengths of the light.…”

Section: Longitudinal Variationssupporting

confidence: 82%

The spectrum of Pluto, 0.40–0.93μm

Lorenzi

Pinilla-Alonso

Licandro

et al. 2016

A&A

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Context. During the past 30 years the surface of Pluto has been characterized and its variability monitored through continuous nearinfrared spectroscopic observations. But in the visible range only a few data are available. Aims. The aim of this work is to define Pluto's relative reflectance in the visible range to characterize the different components of its surface, and to provide ground based observations in support of the New Horizons mission. Methods. We observed Pluto on six nights between May and July 2014 with the imager/spectrograph ACAM at the William Herschel Telescope (La Palma, Spain). The six spectra obtained cover a whole rotation of Pluto (P rot = 6.4 days). For all the spectra, we computed the spectral slope and the depth of the absorption bands of methane ice between 0.62 and 0.90 μm. To search for shifts in the center of the methane bands, which are associated with dilution of CH 4 in N 2 , we compared the bands with reflectances of pure methane ice. Results. All the new spectra show the methane ice absorption bands between 0.62 and 0.90 μm. Computation of the depth of the band at 0.62 μm in the new spectra of Pluto and in the spectra of Makemake and Eris from the literature, allowed us to estimate the Lambert coefficient at this wavelength at temperatures of 30 K and 40 K, which has never been measured before. All the detected bands are blueshifted with respect to the position for pure methane ice, with minimum shifts correlated to the regions where the abundance of methane is higher. This could be indicative of a dilution of CH 4 :N 2 that is more saturated in CH 4 . The longitudinal and secular variations in the parameters measured in the spectra are in accordance with results previously reported in the literature and with the distribution of the dark and bright materials that show the Pluto's color maps from New Horizons.

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Section: Longitudinal Variationssupporting

confidence: 82%

The spectrum of Pluto, 0.40–0.93μm

Lorenzi

Pinilla-Alonso

Licandro

et al. 2016

A&A

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“…Seasonal variation of the atmospheric pressure and the surface ice abundances have been expected and measured by several authors from stellar occultations (Elliot et al 2003;Sicardy et al 2003). To constrain the spatial distribution and secular evolution of the main ices on the surface of Pluto, Grundy et al (2013Grundy et al ( , 2014 observed this object from 2001 to 2012. They clearly found spatial variation of the N 2 , CH 4 , and CO physical properties (abundances and/or textures) as well as secular modification.…”

Section: Introductionmentioning

confidence: 88%

“…3. We define geometry on Pluto as in Grundy et al (2013): "using a right-hand-rule coordinate system in which North is the direction of Pluto's spin vector and East is the direction of sunrise. Zero longitude is defined by the sub-Charon point.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…We synthesized each of the 100 spectra from the initial spectrum adding a random value, wavelength per wavelength, comprised within one standard deviation. We used the same method to compute the fractional band depth and its error, following the instruction provided by Grundy et al (2013) to choose the anchor points (i.e., continuum and minimum of the bands) for comparison purpose. We changed the wavelength window of the second continuum for all the bands ([1.97−1.99] μm instead of [1.98−2.01] μm) to avoid error due to the telluric bands that were not completely removed during the spectral extraction step and located shortly after 2 μm.…”

Section: Spatial Variationmentioning

confidence: 99%

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New constraints on the surface of Pluto

Merlin

2015

A&A

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Aims. Spectroscopic investigation of the surface of Pluto allows us to constrain the chemical properties of the volatile species of the solar system reservoir. This permits us to obtain the relative abundances of various molecules, their physical properties, as well as their spatial and temporal variation. This also could tell us about the origin of various minor chemical compounds formed during the solar system formation or generated later on by space weathering. This will give us critical information about the evolution processes that may occur in the entire trans-Neptunian objects population, and in particular the biggest objects, which could retain tenuous atmospheres. Methods. New observations of the surface of Pluto have been carried out along with reanalyses of older observations carried out with the ESO-VLT telescopes and the SINFONI instrument at a mean spectral resolution of 1500. We present three new near-infrared spectra of Pluto observed at different epochs, and covering the H and K spectral bands showing absorption features of methane, nitrogen, and carbon monoxide ices. We ran different spectral models, based on Hapke theory, to constrain the physical and chemical properties of different sides of Pluto. Results. We have confirmed the spatial and secular variation of the spectral properties of the surface of Pluto. The abundances, sizes, and temperatures of different ices, such as CH 4 , CO, and N 2 have been constrained for different parts of the surface of Pluto. The results suggest a temperature probably just above the alpha-beta transition phase of N 2 (close to 36.5 K), and a probable stratification of the dilution state of CO and CH 4 . The presence of minor chemical compounds, such as C 2 H 6 , has been confirmed too, and for data obtained at several sub-Earth east longitudes. Solid C 2 H 4 is suggested by the spectral modeling with abundance variation following that of solid C 2 H 6 and solid CH 4 .

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“…This spectral region is accessible to Earth-based spectroscopy of Pluto and related objects (e.g., Grundy et al 2013), and is also covered by the LEISA spectrometer on board the New Horizons spacecraft, which encountered Pluto and its satellites in 2015 July (Young et al 2008). The laboratory spectra and identifications presented here will inform the analysis of infrared spectroscopy of Pluto and related objects, with particular emphasis on the non-ice component(s) of their surfaces.…”

Section: Infrared Spectroscopymentioning

confidence: 99%

ICE CHEMISTRY ON OUTER SOLAR SYSTEM BODIES: ELECTRON RADIOLYSIS OF N₂-, CH₄-, AND CO-CONTAINING ICES

Materese

Cruikshank

Sandford

et al. 2015

ApJ

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Radiation processing of the surface ices of outer Solar System bodies may be an important process for the production of complex chemical species. The refractory materials resulting from radiation processing of known ices are thought to impart to them a red or brown color, as perceived in the visible spectral region. In this work, we analyzed the refractory materials produced from the 1.2-keV electron bombardment of low-temperature N 2 -, CH 4 -, and CO-containing ices (100:1:1), which simulates the radiation from the secondary electrons produced by cosmic ray bombardment of the surface ices of Pluto. Despite starting with extremely simple ices dominated by N 2 , electron irradiation processing results in the production of refractory material with complex oxygen-and nitrogenbearing organic molecules. These refractory materials were studied at room temperature using multiple analytical techniques including Fourier-transform infrared spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). Infrared spectra of the refractory material suggest the presence of alcohols, carboxylic acids, ketones, aldehydes, amines, and nitriles. XANES spectra of the material indicate the presence of carboxyl groups, amides, urea, and nitriles, and are thus consistent with the IR data. Atomic abundance ratios for the bulk composition of these residues from XANES analysis show that the organic residues are extremely N-rich, having ratios of N/C ∼ 0.9 and O/C ∼ 0.2. Finally, GC-MS data reveal that the residues contain urea as well as numerous carboxylic acids, some of which are of interest for prebiotic and biological chemistries.

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Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

Cited by 73 publications

References 67 publications

The spectrum of Pluto, 0.40–0.93μm

The spectrum of Pluto, 0.40–0.93μm

New constraints on the surface of Pluto

ICE CHEMISTRY ON OUTER SOLAR SYSTEM BODIES: ELECTRON RADIOLYSIS OF N₂-, CH₄-, AND CO-CONTAINING ICES

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Near-infrared spectral monitoring of Pluto’s ices: Spatial distribution and secular evolution

Cited by 73 publications

References 67 publications

The spectrum of Pluto, 0.40–0.93μm

The spectrum of Pluto, 0.40–0.93μm

New constraints on the surface of Pluto

ICE CHEMISTRY ON OUTER SOLAR SYSTEM BODIES: ELECTRON RADIOLYSIS OF N2-, CH4-, AND CO-CONTAINING ICES

Contact Info

Product

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About

ICE CHEMISTRY ON OUTER SOLAR SYSTEM BODIES: ELECTRON RADIOLYSIS OF N₂-, CH₄-, AND CO-CONTAINING ICES