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Pluto’s Haze from 2002 - 2015: Correlation with the Solar Cycle


Young, E and Klein, V and Hartig, K and Resnick, A and Mackie, J and Carriazo, C and Watson, C and Skrutskie, M and Verbiscer, A and Nelson, M and Howell, R and Wasserman, L and Hudson, G and Gault, D and Barry, T and Sicardy, B and Cole, A and Giles, B and Hill, K, Pluto's Haze from 2002 - 2015: Correlation with the Solar Cycle, Geophysical Research Abstracts, 23-28 April 2017, Vienna, Austria (2017) [Conference Extract]

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Occultations by Pluto were observed 2002, 2007, 2011 and 2015, with each event observed simultaneously in two or more wavelengths. Separate wavelengths allow us to discriminate between haze opacity and refractive effects due to an atmosphere’s thermal profile – these two effects are notoriously hard to separate if only single-wavelength lightcurves are available. Of those four occultations, the amount of haze in Pluto’s atmosphere was highest in 2002 (Elliot et al. 2003 report an optical depth of 0.11 at 0.73 μm in the zenith direction), but undetectable in the 2007 and 2011 events (we find optical depth upper limits of 0.012 and 0.010 at 0.6 μm). Cheng et al. (2016) report a zenith optical depth of 0.018 at 0.6 μm from the haze profiles seen in New Horizons images. These four data points are correlated with the solar cycle. The 2002 haze detection occurred just after the peak of solar cycle 23, the 2007 and 2011 non-detections occurred during the solar minimum between peaks 23 and 24, and the New Horizons flyby took place just after the peak of solar cycle 24. This suggests that haze production on Pluto (a) is driven by solar UV photons or charged particles, (b) that sources and sinks on Pluto have timescales shorter than a few Earth years, and (c) the haze precursors on Pluto are not produced by Lyman-alpha radiation, because Lyman-alpha output only decreased by about one third in between the cycle 23 and 24 peaks, much less than the observed change in Pluto’s haze abundances.

Item Details

Item Type:Conference Extract
Keywords:pluto, atmospheric composition, solar cycle
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Planetary science (excl. solar system and planetary geology)
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, A (Associate Professor Andrew Cole)
UTAS Author:Giles, B (Dr Barry Giles)
UTAS Author:Hill, K (Dr Kym Hill)
ID Code:117646
Year Published:2017
Deposited By:Mathematics and Physics
Deposited On:2017-06-22
Last Modified:2019-09-23

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