David EhrenreichGrenoble Institute of Planetology and Astrophysics (IPAG)
Alain Lecavelier des Etangs (IAP)David K. Sing (U Exeter)J.-M. Désert (Harvard)
Transmission spectra of exoplanet atmospheres
Primary transit
Primary transit
The planet (partially) eclipses the starTransmission spectroscopy through the limb
Chromatic variations of the optically-thick radius
∆F/F (λ) ≈ [Rp(λ)/R�]2
larger absorptions = larger radius/altitudeSeager & Sasselov (2000) • Brown (2001) • Hubbard et al. (2001) • Ehrenreich et al. (2006)
Phase
No
rmal
ised
flux
883 nm
767 nm
758 nm
679 nm
GranTeCanspectrophotometryhot jupiter XO-2bSing et al. (2011)
Chromatic variations of the optically-thick radius
∆F/F (λ) ≈ [Rp(λ)/R�]2
larger absorptions = larger radius/altitudeSeager & Sasselov (2000) • Brown (2001) • Hubbard et al. (2001) • Ehrenreich et al. (2006)
GranTeCanspectrophotometryhot jupiter XO-2bSing et al. (2011)Fernandez et al. (2009)Fortney et al. (2010)
Wavelength (Å)
Pla
net
rad
ius
(RJ)
Chromatic variations of the optically-thick radius
scale height
H = kBT/µg
(ΔF/F)atmo ≈ 2(ΔF/F)p (H/Rp)
Winn (2010)
Chromatic variations of the optically-thick radius
scale height
H = kBT/µg
(ΔF/F)atmo ≈ 2(ΔF/F)p (H/Rp)
Winn (2010)
10-210-4–10-3 ~500 km
Chromatic variations of the optically-thick radius
scale height
H = kBT/µg
(ΔF/F)atmo ≈ 2(ΔF/F)p (H/Rp)
Winn (2010)
10-510-6–10-7 ~10 km
10-210-4–10-3 ~500 km
Brighter star, better atmospheric detection
S/N ∝�F�
A background light source is required for transmission spectroscopy:
the transited star
Space- & ground-based results, from UV to NIR
• In the visible from the ground with Subaru & GranTeCan
High-resolution detection of atmospheric tracers (Na & K)
• In the visible/NIR from space with the HSTHD 209458b: temperature inversion & diffusionHD1897333b: diffusion by haze
• In the UV from space with the HSTAtmospheric evaporation of hot jupiters
• In the NIR from space with Spitzer & HST/Nicmos
Molecular composition of hot gas giants
Focus on a couple of studies
• In the visible from the ground with Subaru & GranTeCan
High-resolution detection of atmospheric tracers (Na & K)
• In the visible/NIR from space with the HSTHD 209458b: temperature inversion & diffusionHD1897333b: diffusion by haze
• In the UV from space with the HSTAtmospheric evaporation of hot jupiters
• In the NIR from space with Spitzer & HST/Nicmos
Molecular composition of hot gas giants
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Rayleigh scattering by H2
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
broad Na “plateau”
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Rayleigh scattering by H2
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
HST/STIS med res
broad Na “plateau”
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Rayleigh scattering by H2
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
HST/STIS med res
broad Na “plateau”
narrow Na core
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Na depletion• ionization?• condensation?
Rayleigh scattering by H2
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
HST/STIS med res
broad Na “plateau”
narrow Na core
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Na depletion• ionization?• condensation?
Rayleigh scattering by H2
modelTiO/VO
drivingthermal
inversion?
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
HST/STIS med res
broad Na “plateau”
narrow Na core
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Na depletion• ionization?• condensation?
Rayleigh scattering by H2
modelTiO/VO
drivingthermal
inversion?
Charbonneau et al. (2002) • Sing et al. (2008a,b) • Snellen et al. (2008) • Lecavelier et al. (2008) • Désert et al. (2008)
Atmospheric properties of a hot jupiter
HD 209458b HST/STIS low res
HST/STIS med res
broad Na “plateau”
narrow Na core
Wavelength (Å)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Temperature inversion
2000
Sing et al. (2008a,b) • Charbonneau et al. (2002) • Snellen et al.(2008)
1500
12501000
750
500
isotherms (K)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Wavelength (Å)
Temperature inversion
2000
Sing et al. (2008a,b) • Charbonneau et al. (2002) • Snellen et al.(2008)
1500
12501000
750
500
isotherms (K)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Wavelength (Å)
Temperature inversion
2000
Sing et al. (2008a,b) • Charbonneau et al. (2002) • Snellen et al.(2008)
1500
12501000
750
500
isotherms (K)
Ab
sorp
tio
n d
epth
(%)
Altitud
e (km)
Wavelength (Å)
Vidal-Madjar et al. (2011)
Connection to the upper atmosphere
lower atmosphere T-P profilesBarman et al. 2005 • Showman et al. 2008 •Guillot 2010
upper atmosphere T-P profileYelle (2004)
10,000 Kthermosphere
EUV heating
Temperature (K)
Pre
ssur
e (b
ar)
Primary transit
The planet (partially) eclipses the star➡ Transmission spectroscopy through the limb
absorption~1%
~0.01%
Transits in HI Lyman-α (1216 Å) ➡ Exospheric studies (dynamics & composition)
absorption~1%
~10%
evaporatinghydrogen
upper atmosphere
Primary transit in the UV
Escape of light & heavy elements from HD209458b
C II lines 7.8±1.3%
Si III 1206 Å8.2±1.4%
Vidal-Madjar et al. (2003, 2004) • Linsky et al. (2010) • see also: Ehrenreich et al. (2008) • Fossati et al. (2010)
HST/COS HST/COS
HST/STIS
Wavelength (Å)
Velocity (km s-1) Velocity (km s-1)
Flux
(10-1
4 er
g c
m-2
s-1
Å-1
)Fl
ux (1
0-15
erg
cm
-2 s
-1 Å
-1)
Escape of light & heavy elements from HD209458b
C II lines 7.8±1.3%
Si III 1206 Å8.2±1.4%
Vidal-Madjar et al. (2003, 2004) • Linsky et al. (2010) • see also: Ehrenreich et al. (2008) • Fossati et al. (2010)
HST/COS HST/COS
HST/STIS
Wavelength (Å)
Velocity (km s-1) Velocity (km s-1)
Flux
(10-1
4 er
g c
m-2
s-1
Å-1
)Fl
ux (1
0-15
erg
cm
-2 s
-1 Å
-1)
➡ Hydrodynamical mass lossH flow carrying up heavier species
HST/ACS
Another case of evaporating hot jupiter: HD 189733b
Lecavelier des Etangs et al. (2010)
HST/ACS
Another case of evaporating hot jupiter: HD 189733b
Lecavelier des Etangs et al. (2010)
HST/ACS
Another case of evaporating hot jupiter: HD 189733b
Lecavelier des Etangs et al. (2010)
HI Lyα 5.1±0.8%
transit in the visible is 2.4%
HST/ACS
Another case of evaporating hot jupiter: HD 189733b
Lecavelier des Etangs et al. (2010)
mass-loss rate ~ 1010 g s-1
hot jupiters are stable➡ lifetime estimations
HI Lyα 5.1±0.8%
transit in the visible is 2.4%
Lifetime heating efficiency=15%
GJ436b
WASP-17b
WASP-12b
HD80606b
Kepler-10bGJ1214bCorot-7b
Kepler-9d
WASP-33b
HD189733b
HD209458b
Ehrenreich & Désert (2011) • also: Lecavelier (2007) • Davies & Wheatley (2009) • Lammer et al. (2009)
Log [Incident X/EUV energy on top of the atmosphere (erg Gyr-1)]
Log
[Gra
vita
tio
nal p
ote
ntia
l ene
rgy
(erg
)]
Lifetime heating efficiency=15%
GJ436b
WASP-17b
WASP-12b
HD80606b
Kepler-10bGJ1214bCorot-7b
Kepler-9d
WASP-33b
HD189733b
HD209458b
Ehrenreich & Désert (2011) • also: Lecavelier (2007) • Davies & Wheatley (2009) • Lammer et al. (2009)
Log [Incident X/EUV energy on top of the atmosphere (erg Gyr-1)]
Log
[Gra
vita
tio
nal p
ote
ntia
l ene
rgy
(erg
)]
46 44 42 40 38 36Log(<dEEUV/dt> [erg Gyr-1])
40
41
42
43
44
45
46
47
Lo
g(-
Ep’ [
erg
])
1 Gyr
5 Gyr
10 GyrLifetime
HD80606b
< 200 pc
Atmospheric tracer (HI) absorbed by ISM ➡ nearby targets necessary!PLATO will survey 5000+ nearby M-dwarf stars bright@Lyα
Present-day transit surveys detect VIPs (mostly) at large distances
too farto monitor@Lyα
Log [Incident X/EUV energy on top of the atmosphere (erg Gyr-1)]
Log
[Gra
vita
tio
nal p
ote
ntia
l ene
rgy
(erg
)]
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
Why we need P l a t o
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
Why we need P l a t o
3σ detection of 1 scale height by HST
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
Why we need P l a t o
3σ detection of 1 scale height by HST
3σ detection of 1 scale height by JWST∅/HST∅
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
Why we need P l a t o
3σ detection of 1 scale height by HST
3σ detection of 1 scale height by JWST∅/HST∅
PLATO planets around bright starspopulation synthesis model welcome to assess
the characterization follow-up possibilities
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
Why we need P l a t o
7
8
9
10
11
12
13
14
15 0,00 0,01 0,02 0,03 0,04 0,05
V (m
ag)
Atmospheric signal of 1 scale height (%)
Known transiting planets
Known transiting planets
...and more
245,000+ stars
20,000+ stars
Why we need P l a t o3,000+ stars
Thank you!
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