Pluto's Non-isothermal Surface

Details Pluto's Non-isothermal Surface Pluto's Non-isothermal Surface

Sep 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000icar..147..220l&link_type=abstract

Icarus, Volume 147, Issue 1, pp. 220-250 (2000).

Computer Science

Sound

25

Scientific paper

We report on repeated far-infrared photometric observations of the Pluto-Charon system conducted in 1997 with the Infrared Space Observatory (ISO). These observations have led to the first detection of the system at 150 and 200 μm and to the first clear detection of its thermal lightcurve at 60 μm (and more marginally at 100 μm). They definitely prove that Pluto's surface is not isothermal. The thermal lightcurve is, as expected, roughly anticorrelated with the visible lightcurve, but not exactly. The data are fit by physical models including Charon and three separate units on Pluto, respectively dominated by (1) N2-ice (2) CH4-ice, and (3) tholins. These models are constructed in accordance with information from visible imaging and lightcurves, visible spectroscopy and infrared spectroscopy, and considerations on the thermal balance of N2 and CH4, and they include a thermophysical description of subsurface conduction and infrared beaming. Charon's contribution, which cannot be separated from Pluto's in the observations, is assumed to be independent of longitude and equivalent to that of a ~52 K body. The main implications are that Pluto's surface in units 2 and 3 has a thermal inertia Γ=(1.5-10)×104 erg cm-2 s-1/2 K-1, comparable to that of other icy satellites, and relatively high bolometric emissivities (not lower than 0.5 and most likely 0.8-1). Diurnal temperature variations must be significant, with maximum dayside temperatures in the range 54-63 K. The value of thermal inertia may be indicative of porosity in the top centimeters of Pluto's surface. The observations further confirm that the far-IR brightness temperatures, though somewhat smaller than indicated by IRAS, are higher than in the millimeter/submillimeter range. Extending the models to longer wavelengths suggests that a low radio emissivity, as opposed to a mixing of temperatures or a subsurface sounding effect, is the correct explanation. Finally, in spite of large error bars, the 150-μm fluxes indicated by ISO seem unexpectedly high given the spectral properties of ices in the far-IR. These, and the expected lightcurves of the Pluto-Charon system at λ=15-60 μm should be priority measurements for SIRTF.

Affiliated with

Also associated with

No associations

Rating

Pluto's Non-isothermal Surface does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Pluto's Non-isothermal Surface, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pluto's Non-isothermal Surface will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1386557