January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Pluto occultation 2006 June 12from Australia & New Zealand

Leslie Young, Eliot Young, Catherine Ruhland, Catherine Olkin (SwRI)

Richard French (Wellesley College)Marc Buie (Lowell Observatory)Jeff Regester (Greensboro Day School, NC)Kevin Shoemaker (Shoemaker Labs, Longmont CO)Martin George (Launceston Planetarium, Tasmania)John Broughton (Reedy Creek, Australia)Grant Christie,Tim Natusch (Auckland Observatory)Ross Dickie, Peter Jaquiery, Graham Blow (RASNZ)Dave Gault (Hawkesbury Heights, Australia)Blair Lade (Stockport Observatory, Australia)

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Occultation Overview

Temperature PressureExtinction

Refractivity Bending

angle=>

Flux Position in shadow

=>=>

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Occultation:Reconstructed Shadow Path

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Reedy Creek 0.51 m (20")John Broughton

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Anglo-Australian Telescope 4-m (163 ")Dick French, Kevin Shoemaker

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Hawkesbury Heights 0.25 m (10")Dave Gault

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Stockport Observatory 0.51 m (20")Blair Lade

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Longford Farm 0.36 m (14")Eliot Young, Jeff Register

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Auckland Observatory 0.36 m (14")Grant Christie, Tim Natusch

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Carter Observatory 0.41 m (16")Marc Buie, Trina Ruhland

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Farm near Wanaka, 0.36 m (14")Leslie Young, Cathy Olkin, Peter Jaquirey, Ross Dickie

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Geometric Solution

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Geometric Solution

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Change in Shadow Radius:1988 to 2002: 2.74 ± 1.36 km/yr (increase)

2002 to 2006: 1.17 ± 4.31 km/yr (consistent with no change)

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Frame Rate: 10 Hz

SNR per point: 62

SNR per 60 km: 331

GPS-based absolute timing accuracy better than 100 µsecond.

Spikes are resolved, differ in detail between ingress/egress

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

T0

2006 AAT 2006 AAT 2006 AAT 1988 KAOIngress Egress Avg Avg

T0 (K) 100.0±4.2 106.4±4.6 103.9±3.2 104.0±7.3

P0 (µbar) 1.76±0.14 1.95±0.15 1.86±0.10 0.83±0.11

dT0/dr (K/km) -0.113±0.045 -0.082±0.051 -0.086±0.033 -0.040±0.052

r1 (km) 1286.8±10.6 1287.1±37.1 1273.6±7.1 1215.8±1.3

κ2 (1000xkm-1) 2.7±0.5 3.0±0.5 3.0±0.4 4.1±0.3

Hτ216.6±1.7 15.9±1.8 15.9±1.1 24.6±4.2

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Lower Atmosphere Inversion(Ref: Elliot, Person and Qu 2003)

• Small Planet Case• No Ray Crossing• Geometric Optics• Clear Atmosphere

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Immersion

R (km) v. T (K) R (km) v. dT/dr (K/km)

dry adiabat

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Emersion

R (km) v. T (K) R (km) v. dT/dr (K/km)

dry adiabat

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Monte Carlo-Based Error Estimates

• Monte Carlo errors based on 100 simulated lightcurves with appropriate noise.

• The Temperature Inversions: Similar overall shape, similar wiggles, but largest errors (up to ±18 K) above the temperature inversion at 1240 km.

R (km) v. T (K)- Nominal Case- 1-sigma env.

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Effects of an example haze layer

• Haze dramatically changes the lower temperature profile.

• Brings dT/dr closer to a dry adiabat.

Consider the effects of sudden haze onset at 1263 km with a scale height of 15 km.

R (km) v. T (K)

R (km) v. dT/dr (K/km)dry adiabat

January 11, 2007 Workshop 3e Zone, Nantes. Leslie Young

Conclusions• Pluto's bulk atmosphere (geometry):

– 1988 to 2006, pressure has increased by 0.98 ± 0.09 µbar, a factor of 2.17±0.21

– For N2 surface vapor pressure equilibrium, this implies an increase in surface temperature of 1.2-1.7 K.

– Pressures consistant between 2002 and 2006

• Pluto’s upper atmosphere (model fit): – Non-isothermal. dT/dr = -0.127±0.028 K/km– Average (103.9±3.2 K) same as 2002 (104±2 K, isothermal fit),

and 1988 (104.0±7.3 K). – 99.4±3.1 K (ingress, 30.0 S, summer), 105.5±3.5 K (egress, 53.2 N, winter)

dispite ~1500 less insolation averaged over the winter latitude, so not tied to insolation (in a straightforward way)

• Pluto’s lower atm, clear assumption (inversion):– As in 1988 & 2002, not isothermal. – Temperature inversion around 1210 - 1220 km.– Ingress & Egress are qualitatively similar, but the density perturbations differ in detail.

• Pluto’s lower atm, haze assumption (inversion, removing haze from model fit)– Top of haze poorly constrained.– Temperature purturbations qualitatively similar to those seen on Earth, Jupiter, Titan