Bruno Sicardy Obs. Paris - LESIA and occcultation Team PHYSIQUE DE L'ATMOSPHÈRE DE PLUTON ET TAILLE DE CHARON DÉDUITES D'OCCULTATIONS STELLAIRES 2002-2006 François Colas Thomas Widemann Atelier 3ème zone, Nantes 11-12 janvier 2007
Apr 03, 2015
Bruno SicardyObs. Paris - LESIA
and occcultation Team
Bruno SicardyObs. Paris - LESIA
and occcultation Team
PHYSIQUE DE L'ATMOSPHÈRE DE PLUTON ET TAILLE DE CHARON DÉDUITES
D'OCCULTATIONS STELLAIRES 2002-2006
PHYSIQUE DE L'ATMOSPHÈRE DE PLUTON ET TAILLE DE CHARON DÉDUITES
D'OCCULTATIONS STELLAIRES 2002-2006
François ColasFrançois ColasThomas WidemannThomas Widemann
Atelier 3ème zone, Nantes 11-12 janvier 2007
Atelier 3ème zone, Nantes 11-12 janvier 2007
special moment: equinox in 1988, perihelium in 1989 (period 248 years) effects on N2 pressure-equilibirum atmosphere?
Charon's size? ( density ?)
Charon's surface gravity ~ 1/2 Pluto's gravity possibility of atmosphere?
Pluto and Charonprobed by occultations
C.J Hansen & D.A. Paige Icarus, 120, 247-265 (1996)
complex interplay of large distance variations & drastic seasonal effects
2001
2020
2011
Pluto motion in the sky
Pluton 20 juil. 2002
P131.1 August 21, 2002
spikes: scintillation in Pluto’s atmosphere
temperature contrast:warmer near pole cooler near equator
Sicardy et al. Nature, 10 July 2003
Sicardy et al. Nature, July 2003
Imm. Eme.
Sicardy et al. « Large changes in Pluto’s atmosphere
as revealed by recent stellar occultations »
Nature, 10 July 2003
1988
2002
2006
pressure doubled!
?
Time
rP
B'P
rN
1988
2002
2006
C.J Hansen & D.A. Paige Icarus, 120, 247-265 (1996)
1900 2000 2100
10 bar
1 bar
0.1 bar
Pluto in 1988
Pluto in 2002
measuring Charon
0.89"
2UCAC 26257135(D. Herald, Aug. 2004)
QuickTime™ et undécompresseur Vidéo
sont requis pour visionner cette image.
VLT/NACO K band, Charon occultation 11 July 2005
1"
Pluto
star + Charon
Sicardy et al., Nature 439, 52, 2006« Charon’s size and an upper limiton its atmosphere from a stellaroccultation »
R= 603.61.4 km
56 K - N2100 K - CH4
56 K
Some conclusions:
Atmosphere: limit is model dependent, e.g.
CH4 with inversion layer: psurf < 15 nbar…or…N2 isothermal 56 K: psurf < 110 nbar etc…
Charon’s size: RC = 603.6 1.4 km
Charon’s density: C = 1.65 0.06 g cm-3
(taken from Buie et al. AJ. 132, 290, 2006, NB. P = 2.03 0.06 g cm-3 for Pluto)
Possibility to retrieve Pluto’s radius with accurate Charon’saccurate size --> refine atmospheric model
recent & future stuff…
12 June 2006 Pluto occultation
1988 2002
12 June 2006, Australia
Stockport
Blue Mountains
Hobart
20 cm
40 cm
50 cm
Time (sec UT)
Stockport
Blue Mountains
Hobart
pressure expansion factor since 2002
68.3% c.l.
99.7% c.l.
2
1988 2002
2006
Hansen & Paige, Icarus 120, 247 (1996)
1988
20022006
pressure @ 1215 km(bar)
10
1
5
2
time (year)
New Horizon
2007: four Pluto & co events?
Nix, 22 mars 2007
2.1"
Hydra
Pluto **et** Hydra12 mai 2007
Paranal & La Silla
Pluton14 juin 2007
Paranal, La Silla & SOAR
en cours:
prédictions d'occultations par de gros TNO
Eris, 2005 FY9, 2003 EL6, Sedna, Orcus,Quaoar, Varuna, … (voir présentation T. Widemann)
Paranal Jul 2005
… merci