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PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
PLUTO'S ATMOSPHERE FROM
STELLAR OCCULTATIONS IN 2012 AND
2013
Alex Dias de OliveiraSicardy, B., Lellouch, E., Vieira-Martins, R., Assa�n, M., Camargo, J. I. B.,J. I. B.,
Braga-Ribas, F., Gomes-Júnior, A. R., Benedetti-Rossi, G., Colas, F., Decock, A., Doressoundiram,
A., Dumas, C., Emilio, M., Fabrega Polleri, J., Gil-Hutton, R., Gillon, M., Girard, J., Hau, G. K.
T., Ivanov, V. D., Jehin, E., Lecacheux, J., Leiva, R. Lopez-Sisterna, C., Mancini, L., Manfroid, J.,
Maury, A., Meza, E., Morales, N., Nagy, L., Opitom, C., Ortiz, J. L., Pollock, J., Roques, F.,
Snodgrass, C., Soulier, J.F., Thirouin, A., Vanzi, L., Widemann, T., Reichart, D. E., LaCluyze, A.
P., Haislip, J. B., Ivarsen, K. M., Dominik, M., Jørgensen, U., Skottfelt, J.
3 de setembro de 2015
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Summary
Summary
Introduction
Events (Prediction, Observation and Calibration)
Modeling
General atmospheric structure
Stratosphere
Mesosphere negative temperature gradient
Conclusions
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Why study Pluto's atmosphere?
Low incidence of solar radiation - Origin andevolution of the Solar System.
Atmospheric structure - Correct interpretation ofobservational data (spectra).
Appearance and maintenance of atmospheres -Other trans-neptunian objects with size and surfacegravity comparable to those of Pluto within a factor oftwo, exihibited none atmosphere at the 10 nbar pressurelevel.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Why study Pluto's atmosphere?
Low incidence of solar radiation - Origin andevolution of the Solar System.
Atmospheric structure - Correct interpretation ofobservational data (spectra).
Appearance and maintenance of atmospheres -Other trans-neptunian objects with size and surfacegravity comparable to those of Pluto within a factor oftwo, exihibited none atmosphere at the 10 nbar pressurelevel.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Why study Pluto's atmosphere?
Low incidence of solar radiation - Origin andevolution of the Solar System.
Atmospheric structure - Correct interpretation ofobservational data (spectra).
Appearance and maintenance of atmospheres -Other trans-neptunian objects with size and surfacegravity comparable to those of Pluto within a factor oftwo, exihibited none atmosphere at the 10 nbar pressurelevel.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
How to study it?
Direct Observation - Spectroscopy. Information aboutthe atmosphere and surface chemichal composition, andsurface temperature.
Indirect Observation - Stellar occultations. Highprecision density, pressure and temperature pro�les.Gravity waves (turbulence). Surface radius andcomposition (Combined with spectroscopy information).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
How to study it?
Direct Observation - Spectroscopy. Information aboutthe atmosphere and surface chemichal composition, andsurface temperature.
Indirect Observation - Stellar occultations. Highprecision density, pressure and temperature pro�les.Gravity waves (turbulence). Surface radius andcomposition (Combined with spectroscopy information).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Stellar Occultaions
Consists into analyze the time variation of the star light,while crossing the atmosphere of the occulting object.
As far as ground based observations are concern, it is themost e�ective technique available to study Pluto'satmosphere. It allows an atmospheric probe to nbar levels(Sicardy et al., 2011; Olkin et al., 2014).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Stellar Occultaions
Consists into analyze the time variation of the star light,while crossing the atmosphere of the occulting object.
As far as ground based observations are concern, it is themost e�ective technique available to study Pluto'satmosphere. It allows an atmospheric probe to nbar levels(Sicardy et al., 2011; Olkin et al., 2014).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Introduction
Stellar Occultations
Responsable for Pluto's atmosphere discovery (Hubbardet al., 1988; Elliot et al., 1989; Brosch, 1995).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Prediction
Prediction catalog - Assa�n et al. (2010) ObservedPluto's path in the sky plane bewteen 2008 e 2015,performed at ESO's 2,2 m telescope.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Prediction
Predicted events observed at South America with ESO's8.2 m VLT, among others.
July 18, 2012 - R* 14 May 4, 2013 - R* 13,7
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Observation
Event - July 18, 2012.
1.50x104 1.51x104 1.52x104 1.53x1040.0
0.5
1.0
1.5
1.505x104 1.510x104 1.515x104 1.520x104 1.525x104
0.7
0.8
0.9
1.0
1.1
1.510x104 1.515x104 1.520x104 1.525x1040.0
0.2
0.4
0.6
0.8
1.0
1.2
1.510x104 1.515x104 1.520x104 1.525x1040.7
0.8
0.9
1.0
1.1
1.2
1.510x104 1.515x104 1.520x104 1.525x1040.7
0.8
0.9
1.0
1.1
1.2
Flux
o
Segundos a partir de 00h (UTC)
Flux
o
Huancayo
Segundos a partir de 00h (UTC)
São Pedro de Atacama
Flux
o
Segundos a partir de 00h (UTC)
Paranal VLT/ESO Cerro Burek
Flux
o
Segundos a partir de 00h (UTC)
Flux
o
Segundos a partir de 00h (UTC)
Santa Martina
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Observation
Event - May 4, 2013.
3.00x104 3.01x104 3.02x104 3.03x104 3.04x1040.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
3.00x104 3.02x104 3.04x1040.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
3.00x104 3.02x104 3.04x104
0.5
0.6
0.7
0.8
0.9
1.0
1.1
3.00x104 3.01x104 3.02x104 3.03x104 3.04x104
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
3.00x104 3.01x104 3.02x104 3.03x104 3.04x104
0.5
0.6
0.7
0.8
0.9
1.0
1.1
3.00x104 3.01x104 3.02x104 3.03x104 3.04x104
0.0
0.2
0.4
0.6
0.8
1.0
Caisey f/6,8
Flux
o
Segundos a partir de 00h (UTC)
Caisey f/8
Cerro Tololo
La Silla
Flux
o
Segundos a partir de 00h (UTC)
São Pedro de Atacama
Flux
o
Segundos a partir de 00h (UTC)
TRAPPIST
Flux
o
Segundos a partir de 00h (UTC)
DANISH
Flux
o
Segundos a partir de 00h (UTC)
PROMPT
Flux
oSegundos a partir de 00h (UTC)
LCGOT
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Calibration
Digital coronography for calibration.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Events
Calibration
Stellar residual �ux varied from 2.3 % to 1.8 % of itsunocculted value.
!"#$%&'#()!(#*+,-#
!"#$%&'$()*+'%,-$.%/0123%4!5%
!)6,7%89:%
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Idea
Assuming a layer model, a incident light ray su�erssuccessives refractions, curving in the atmosphere untilemerge.
R a i o d e l u z i n c i d e n t e
R a i o d e l u z d e s v i a d o
r
θ
r0
P l a n e t a
A t m o s f e r a
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Idea
r0I(r0)=I0 r0
r
raioincidente
(I0)
I (r0) = η(r) · r · senθ
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Model
Total deviation ω(r0) is (Vapillon et al., 1973):
ω(I0) =
∫ ∞r0
2I0η(r)
· dη(r)
dr· dr√
[η(r) · r ]2 − [η(r0) · r0]2(1)
Inverting for η(r0):
η(r0) = exp
1
π
∫ 0
ω(I0)
log
I (ω)
I0+
√(I (ω)
I0
)2
− 1
· dω
(2)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Model
Total deviation ω(r0) is (Vapillon et al., 1973):
ω(I0) =
∫ ∞r0
2I0η(r)
· dη(r)
dr· dr√
[η(r) · r ]2 − [η(r0) · r0]2(1)
Inverting for η(r0):
η(r0) = exp
1
π
∫ 0
ω(I0)
log
I (ω)
I0+
√(I (ω)
I0
)2
− 1
· dω
(2)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Model
I(t)
dIz(t)
dz
(t)
D
Z'
0
I'
For small ω(r0) :
z(t) = I (t) + D · ω(t) (3)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General ModelBy energy conservation we can write:
Φ(t)
Φ0=
dI (t)
dz(t)(4)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Model
Φ(t)
Φ0= f · dI (t)
dz(t)where f = I (t)/z(t) (5)
ω(t) =1
D·∫
t
−∞
f · Φ0 − Φ(τ)
f · Φ0· dzdτ
dτ (6)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Reduction Approaches
Inversion:
From the event data (Φ(t)/Φ0 and z(t)), we calculateI (t) e ω(t).
From general model (Vapillon et al., 1973), we use I (t)and ω(t) to get η(r).
From η(r), we use a atmospheric model (assumptions) todetermine T (r), n(r) e P(r).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Reduction Approaches
Inversion:
From the event data (Φ(t)/Φ0 and z(t)), we calculateI (t) e ω(t).
From general model (Vapillon et al., 1973), we use I (t)and ω(t) to get η(r).
From η(r), we use a atmospheric model (assumptions) todetermine T (r), n(r) e P(r).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Reduction Approaches
Inversion:
From the event data (Φ(t)/Φ0 and z(t)), we calculateI (t) e ω(t).
From general model (Vapillon et al., 1973), we use I (t)and ω(t) to get η(r).
From η(r), we use a atmospheric model (assumptions) todetermine T (r), n(r) e P(r).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Idea
Ray Tracing:
From an atmospheric model (T (r), n(r) e P(r)) wecalculate η(r).
Using η(r) and the general model, we have ω(I0) for eachI (t).
From values of I (t) and ω(t) We calculate syntheticvalues for Φ(t)/Φ0 and z(t).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Idea
Ray Tracing:
From an atmospheric model (T (r), n(r) e P(r)) wecalculate η(r).
Using η(r) and the general model, we have ω(I0) for eachI (t).
From values of I (t) and ω(t) We calculate syntheticvalues for Φ(t)/Φ0 and z(t).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
General Idea
Ray Tracing:
From an atmospheric model (T (r), n(r) e P(r)) wecalculate η(r).
Using η(r) and the general model, we have ω(I0) for eachI (t).
From values of I (t) and ω(t) We calculate syntheticvalues for Φ(t)/Φ0 and z(t).
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Pluto and its atmosphere are spherically symmetric.
The atmosphere is Transparent (no Haze).
The atmosphere is an ideal gas in hydrostatic equilibrium.
P(r) = k · T (r) · n(r) anddP
dr= −µ · n(r) · g(r) (7)
1
n· dndr
= −[µ · g(r)
k · T+
1
T· dTdr
](8)
where
g(r) = GM
r2
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Is a pure molecular nitrogen (N2) atmosphere. Otherminor species, like methane, are neglected. De�ningrefractivity as:
ν(r) = η(r) − 1;
ν(r) = K · n(r)
KN = 1,091 · 10−23 + 6,282·10−26
λ2(cm3/molécula)
T (r) is time-independet, i.e. the temperature pro�les arethe same in 2012 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Is a pure molecular nitrogen (N2) atmosphere. Otherminor species, like methane, are neglected. De�ningrefractivity as:
ν(r) = η(r) − 1;
ν(r) = K · n(r)
KN = 1,091 · 10−23 + 6,282·10−26
λ2(cm3/molécula)
T (r) is time-independet, i.e. the temperature pro�les arethe same in 2012 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Is a pure molecular nitrogen (N2) atmosphere. Otherminor species, like methane, are neglected. De�ningrefractivity as:
ν(r) = η(r) − 1;
ν(r) = K · n(r)
KN = 1,091 · 10−23 + 6,282·10−26
λ2(cm3/molécula)
T (r) is time-independet, i.e. the temperature pro�les arethe same in 2012 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Is a pure molecular nitrogen (N2) atmosphere. Otherminor species, like methane, are neglected. De�ningrefractivity as:
ν(r) = η(r) − 1;
ν(r) = K · n(r)
KN = 1,091 · 10−23 + 6,282·10−26
λ2(cm3/molécula)
T (r) is time-independet, i.e. the temperature pro�les arethe same in 2012 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Simplifying assumptions
Is a pure molecular nitrogen (N2) atmosphere. Otherminor species, like methane, are neglected. De�ningrefractivity as:
ν(r) = η(r) − 1;
ν(r) = K · n(r)
KN = 1,091 · 10−23 + 6,282·10−26
λ2(cm3/molécula)
T (r) is time-independet, i.e. the temperature pro�les arethe same in 2012 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Iterative Procedure.
Invert our best signal-to-noise ratio light curve to retrievedensity, pressure and temperature pro�les (n(r), P(r),and T (r)).
With a parametrized T (r) we generate, through directray tracing, synthetic occultation light-curves.
They are simultaneously �tted to all the observedlight-curves to pin down the location of Pluto's shadowcenter relative to the occultation chords for both eventsand the vertical position of temperature pro�le.
With new shadow's center coordinates, the inversion ofthe best light-curve is performed again and theprocedures ir resumed.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Iterative Procedure.
Invert our best signal-to-noise ratio light curve to retrievedensity, pressure and temperature pro�les (n(r), P(r),and T (r)).
With a parametrized T (r) we generate, through directray tracing, synthetic occultation light-curves.
They are simultaneously �tted to all the observedlight-curves to pin down the location of Pluto's shadowcenter relative to the occultation chords for both eventsand the vertical position of temperature pro�le.
With new shadow's center coordinates, the inversion ofthe best light-curve is performed again and theprocedures ir resumed.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Iterative Procedure.
Invert our best signal-to-noise ratio light curve to retrievedensity, pressure and temperature pro�les (n(r), P(r),and T (r)).
With a parametrized T (r) we generate, through directray tracing, synthetic occultation light-curves.
They are simultaneously �tted to all the observedlight-curves to pin down the location of Pluto's shadowcenter relative to the occultation chords for both eventsand the vertical position of temperature pro�le.
With new shadow's center coordinates, the inversion ofthe best light-curve is performed again and theprocedures ir resumed.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Iterative Procedure.
Invert our best signal-to-noise ratio light curve to retrievedensity, pressure and temperature pro�les (n(r), P(r),and T (r)).
With a parametrized T (r) we generate, through directray tracing, synthetic occultation light-curves.
They are simultaneously �tted to all the observedlight-curves to pin down the location of Pluto's shadowcenter relative to the occultation chords for both eventsand the vertical position of temperature pro�le.
With new shadow's center coordinates, the inversion ofthe best light-curve is performed again and theprocedures ir resumed.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Iterative Procedure.
Invert our best signal-to-noise ratio light curve to retrievedensity, pressure and temperature pro�les (n(r), P(r),and T (r)).
With a parametrized T (r) we generate, through directray tracing, synthetic occultation light-curves.
They are simultaneously �tted to all the observedlight-curves to pin down the location of Pluto's shadowcenter relative to the occultation chords for both eventsand the vertical position of temperature pro�le.
With new shadow's center coordinates, the inversion ofthe best light-curve is performed again and theprocedures ir resumed.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Combining the data
Inversion of the light curve from VLT/ESO July 18, 2012event, give a temperature pro�le T (r).
From a parametric form of T (r), we do a ray tracing forMay 4, 2013 event, from which we get the inicial position(ri = r1) of the temperature pro�le.
Using the calculated ri we redo the ray tracing for theJuly 18, 2012 event to determine Pi and the shadowscenter coordinates.
We new center coordinates (z(t)) we redo July 18, 2012event inversion to ger a precise temperature pro�le.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Combining the data
Inversion of the light curve from VLT/ESO July 18, 2012event, give a temperature pro�le T (r).
From a parametric form of T (r), we do a ray tracing forMay 4, 2013 event, from which we get the inicial position(ri = r1) of the temperature pro�le.
Using the calculated ri we redo the ray tracing for theJuly 18, 2012 event to determine Pi and the shadowscenter coordinates.
We new center coordinates (z(t)) we redo July 18, 2012event inversion to ger a precise temperature pro�le.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Combining the data
Inversion of the light curve from VLT/ESO July 18, 2012event, give a temperature pro�le T (r).
From a parametric form of T (r), we do a ray tracing forMay 4, 2013 event, from which we get the inicial position(ri = r1) of the temperature pro�le.
Using the calculated ri we redo the ray tracing for theJuly 18, 2012 event to determine Pi and the shadowscenter coordinates.
We new center coordinates (z(t)) we redo July 18, 2012event inversion to ger a precise temperature pro�le.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Modeling
Combining the data
Inversion of the light curve from VLT/ESO July 18, 2012event, give a temperature pro�le T (r).
From a parametric form of T (r), we do a ray tracing forMay 4, 2013 event, from which we get the inicial position(ri = r1) of the temperature pro�le.
Using the calculated ri we redo the ray tracing for theJuly 18, 2012 event to determine Pi and the shadowscenter coordinates.
We new center coordinates (z(t)) we redo July 18, 2012event inversion to ger a precise temperature pro�le.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Parametrization of T (r)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Parametrization of T (r)
T (r) = T1 +dT
dr· (r − r1), r ≤ r2
C1 · r + C2 · T (r) + C3 · r · T (r) + C4 · r2 + C5 · T (r)2 = 1, r2 ≤ r ≤ r4
T (r) = C6 + C7 · r + C8 · r2 + C9 · r3, r4 ≤ r ≤ r5
T (r) = Tiso r ≥ r5
(9)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Final Temperature Pro�le
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Final Temperature Pro�le
VLT/NACO 18 Jul 2012 ingress
VLT/NACO 18 Jul 2012 egress
VLT/NACO 04 May 2013 ingress
VLT/NACO 04 May 2013 egress
PROMPT 04 May 2013 ingress
PROMPT 04 May 2013 egress
TRAPPIST 04 May 2013 ingress
TRAPPIST 04 May 2013 egress
template profile
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Fitted Light-curves
04:13 UTSanta Martina Cerro Burek
Paranal
Huancayo
San Pedro de Atacama
18 July 2012
iso.
dof
1.19
dof0.945
dof
2.75
dof1.58
dof
1.17
No
r ma l
i zed
Fl u
x
Time
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
General atmospheric structure
Fitted Light-curves
08:22 UTCerro Burek
La SillaTRAPPIST
Paranal
Pico dos Dias
04 May 2013
Cerro Tololo
SP AtacamaCaisey f/6.8Caisey f/8
dof
0.777 dof
1.15
dof
1.49
dof
1.27
dof
0.668
dof
0.986
dof
0.890
Time
No
rmal
i zed
Fl u
x
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Statosphere
Radius determination
1190±5 km
T (K)
r (k
m)
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Mesosphere negative temperature gradient
Possible cooling by CO or HCN
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
Combination of well-sampled occultation chords and highSNR data, have allowed us to constrain the density,temperature and thermal gradient pro�les of Pluto'satmosphere, between radii r ∼ 1,190 km (pressurep ∼ 11 µbar) and r ∼ 1,450 km (pressure p ∼ 0.1 µbar).
We �nd that a unique thermal model, can �t satisfactorilytwelve light-curves observed in 2012 and 2013, assuminga spherically symmetric and clear (no haze) atmoshere.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
Combination of well-sampled occultation chords and highSNR data, have allowed us to constrain the density,temperature and thermal gradient pro�les of Pluto'satmosphere, between radii r ∼ 1,190 km (pressurep ∼ 11 µbar) and r ∼ 1,450 km (pressure p ∼ 0.1 µbar).
We �nd that a unique thermal model, can �t satisfactorilytwelve light-curves observed in 2012 and 2013, assuminga spherically symmetric and clear (no haze) atmoshere.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
Combination of well-sampled occultation chords and highSNR data, have allowed us to constrain the density,temperature and thermal gradient pro�les of Pluto'satmosphere, between radii r ∼ 1,190 km (pressurep ∼ 11 µbar) and r ∼ 1,450 km (pressure p ∼ 0.1 µbar).
We �nd that a unique thermal model, can �t satisfactorilytwelve light-curves observed in 2012 and 2013, assuminga spherically symmetric and clear (no haze) atmoshere.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
ConclusionsThe absolute vertical scale of our global model has aninternal accuracy of about ±1 km. However, this error isampli�ed to ±5 km at the bottom of the pro�les, becauseof the uncertainty on the residual stellar �ux in thecentral part of the occultation observed by NACO on 18July 2012.
In the frame of our model (i.e. assuming a constanttemperature pro�le), we detect a signi�cant 6% pressureincrease (at the 6-σ level), during the ∼9.5 monthsseparating the two events under study. This means thatPluto's atmosphere was still expanding at that time,con�rming the work of Olkin et al. (2015), whichcompiles and analyzes pressure measurements between1988 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
ConclusionsThe absolute vertical scale of our global model has aninternal accuracy of about ±1 km. However, this error isampli�ed to ±5 km at the bottom of the pro�les, becauseof the uncertainty on the residual stellar �ux in thecentral part of the occultation observed by NACO on 18July 2012.
In the frame of our model (i.e. assuming a constanttemperature pro�le), we detect a signi�cant 6% pressureincrease (at the 6-σ level), during the ∼9.5 monthsseparating the two events under study. This means thatPluto's atmosphere was still expanding at that time,con�rming the work of Olkin et al. (2015), whichcompiles and analyzes pressure measurements between1988 and 2013.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
The extrapolation of our temperature pro�les to thenitrogen saturation line, implies that nitrogen maycondense at a Pluto's radius of RP = 1,190± 5 km.
From a Pluto's mass of MP = 1.304± 0.006× 1022 kg(Tholen et al., 2008), we derive a densityρP = (1.802± 0.007)(RP/1,200 km)−3 g cm−3. Ourestimation thus implies ρP = 1.85± 0.02 g cm−3. This islarger, but not by much, than Charon's density,ρC = 1.63± 0.05 g cm−3.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
The extrapolation of our temperature pro�les to thenitrogen saturation line, implies that nitrogen maycondense at a Pluto's radius of RP = 1,190± 5 km.
From a Pluto's mass of MP = 1.304± 0.006× 1022 kg(Tholen et al., 2008), we derive a densityρP = (1.802± 0.007)(RP/1,200 km)−3 g cm−3. Ourestimation thus implies ρP = 1.85± 0.02 g cm−3. This islarger, but not by much, than Charon's density,ρC = 1.63± 0.05 g cm−3.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
Above the stratopause, and up to about 1,390 km, ourbest 2012 and 2013 occultation light-curves yield invertedtemperature pro�les with a negative thermal gradientclose to -0.2 K km−1, which amounts to a total decreaseof 30 K for the temperature between 1,215 and 1,390 km
Explaining this negative gradient by CO cooling requires amixing ratio (200× 10−4), that is too high by a factor of40 compared to current measurements (Lellouch et al.,2011). Cooling by HCN is also discussed in this paper. Itappears to be a possible alternative solution, but only if itremains largely supersaturated in the mesosphere.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
Above the stratopause, and up to about 1,390 km, ourbest 2012 and 2013 occultation light-curves yield invertedtemperature pro�les with a negative thermal gradientclose to -0.2 K km−1, which amounts to a total decreaseof 30 K for the temperature between 1,215 and 1,390 km
Explaining this negative gradient by CO cooling requires amixing ratio (200× 10−4), that is too high by a factor of40 compared to current measurements (Lellouch et al.,2011). Cooling by HCN is also discussed in this paper. Itappears to be a possible alternative solution, but only if itremains largely supersaturated in the mesosphere.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Conclusions
Conclusions
The New Horizons �yby data will provide constraints on the
temperature boundary conditions and atmospheric
composition that will be used to discriminate between the
various solutions decribed here.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Referências
Assa�n, M., Camargo, J.I.B., Vieira Martins, R., Andrei, A.H.,Sicardy, B., Young, L., da Silva Neto, D.N., Braga-Ribas,F., 2010. Precise predictions of stellar occultations by Pluto,Charon, Nix, and Hydra for 2008-2015. Astron. Astrophys.515, A32.
Brosch, N., 1995. The 1985 stellar occultation by Pluto. Mon.Not. R. Astron. Soc. 276, 571�578.
Elliot, J.L., Dunham, E.W., Bosh, A.S., Slivan, S.M., Young,L.A., Wasserman, L.H., Millis, R.L., 1989. Pluto'satmosphere. Icarus 77, 148�170.
Hubbard, W.B., Hunten, D.M., Dieters, S.W., Hill, K.M.,Watson, R.D., 1988. Occultation evidence for anatmosphere on Pluto. Nature 336, 452�454.
Lellouch, E., Stansberry, J., Emery, J., Grundy, W.,Cruikshank, D.P., 2011. Thermal properties of Pluto's and
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Referências
Charon's surfaces from Spitzer observations. Icarus 214,701�716.
Olkin, C.B., Young, L.A., Borncamp, D., Pickles, A., Sicardy,B., Assa�n, M., Bianco, F.B., Buie, M.W., de Oliveira,A.D., Gillon, M., French, R.G., Ramos Gomes, A., Jehin, E.,Morales, N., Opitom, C., Ortiz, J.L., Maury, A., Norbury,M., Braga-Ribas, F., Smith, R., Wasserman, L.H., Young,E.F., Zacharias, M., Zacharias, N., 2015. Evidence thatPluto's atmosphere does not collapse from occultationsincluding the 2013 May 04 event. Icarus 246, 220�225.
Olkin, C.B., Young, L.A., French, R.G., Young, E.F., Buie,M.W., Howell, R.R., Regester, J., Ruhland, C.R., Natusch,T., Ramm, D.J., 2014. Plutos atmospheric structure fromthe July 2007 stellar occultation. Icarus 239, 15�22.
Sicardy, B., Ortiz, J.L., Assa�n, M., Jehin, E., Maury, A.,Lellouch, E., Hutton, R.G., Braga-Ribas, F., Colas, F.,
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Referências
Hestro�er, D., Lecacheux, J., Roques, F., Santos-Sanz, P.,Widemann, T., Morales, N., Du�ard, R., Thirouin, A.,Castro-Tirado, A.J., Jelínek, M., Kubánek, P., Sota, A.,Sánchez-Ramírez, R., Andrei, A.H., Camargo, J.I.B., daSilva Neto, D.N., Gomes, A.R., Martins, R.V., Gillon, M.,Manfroid, J., Tozzi, G.P., Harlingten, C., Saravia, S.,Behrend, R., Mottola, S., Melendo, E.G., Peris, V.,Fabregat, J., Madiedo, J.M., Cuesta, L., Eibe, M.T., Ullán,A., Organero, F., Pastor, S., de Los Reyes, J.A., Pedraz, S.,Castro, A., de La Cueva, I., Muler, G., Steele, I.A., Cebrián,M., Montañés-Rodríguez, P., Oscoz, A., Weaver, D.,Jacques, C., Corradi, W.J.B., Santos, F.P., Reis, W.,Milone, A., Emilio, M., Gutiérrez, L., Vázquez, R.,Hernández-Toledo, H., 2011. A Pluto-like radius and a highalbedo for the dwarf planet Eris from an occultation. Nature478, 493�496.
PLUTO'S ATMOSPHERE FROM STELLAR OCCULTATIONS IN 2012 AND 2013
Referências
Tholen, D.J., Buie, M.W., Grundy, W.M., Elliott, G.T., 2008.Masses of Nix and Hydra. AJ, 135, 777.
Vapillon, L., Combes, M., Lecacheux, J., 1973. The betaScorpii occultation by Jupiter. II. The temperature anddensity pro�les of the Jupiter upper atmosphere.. Astron.Astrophys. 29, 135�149.