Atmosphere Models. Mark Marley, Didier Saumon, Jonathan Fortney, Richard Freedman, Katharina Lodders

Transcription

1 Atmosphere Models Mark Marley, Didier Saumon, Jonathan Fortney, Richard Freedman, Katharina Lodders 1

2 Today Brief atmosphere review Correctly deriving companion properties Some new cloud results: holes & water clouds Polarization of thermal emission 2

3 0.001 Sun P (bar) Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 3

4 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

5 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

6 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

7 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

8 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

9 {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } GPI Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 4

10 !f! /!f! (1.30µm) x Constant TiO K FeH K H 2 O H 2 O H 2 O H 2 O CO CH CH CIA H CH 4 CH 4 CH 4 CH 4 CH 4 NH 3 M6.5 V L5 T.5 Jupiter M6 L5 T5 NH 3 Jupiter CH Wavelength (µm) Marley & Leggett (2009) 5

11 Properties of Companions 6

12 3500 T eff (K) 500 log Age (Gyr) Burrows et al

13 A case study: Gl 570D (T8) - Saumon et al. (2003) Primary (Gl 570A): d = 5.91±0.05pc (Perryman et al. 1997) [Fe/H] = 0.00±0.12 (Feltzing & Gustafsson 1998) Age = 2 5 Gyr (Saumon et al. 2000) Spectroscopy: Optical (Burgasser) Near IR (Leggett) Mʼ (Geballe) Mid IRS (Spitzer/IRS Dim Suns team) ~70% of SED has been sampled 8

14 A case study: Gl 570D (T8) - Saumon et al. (2003) Primary (Gl 570A): d = 5.91±0.05pc (Perryman et al. 1997) [Fe/H] = 0.00±0.12 (Feltzing & Gustafsson 1998) Age = 2 5 Gyr (Saumon et al. 2000) Spectroscopy: Optical (Burgasser) Near IR (Leggett) Mʼ (Geballe) Mid IRS (Spitzer/IRS Dim Suns team) ~70% of SED has been sampled 8

15 Luminosity constrains Teff & g 1) bolometric correction from model spectra M o ) Evolution ) T eff (g) follows from Gyr T eff =800 K log g=5.09 L bol /L o =2.99X10-6 9

16 Luminosity constrains Teff & g 1) bolometric correction from model spectra M o ) Evolution ) T eff (g) follows from Gyr T eff =800 K log g=5.09 L bol /L o =2.99X10-6 9

17 The resulting spectrum (not normalized!) NH 3 λ (µm) Wavelength (µm) 10

18 Wolf 940B T8 companion to M4 dwarf 3 to 10 Gyr age primary Leggett et al. (2010) 11

19 Teff = 575 K Mass ~ 20 to 40 MJup Leggett et al. (2010) 12

20 13

21 Planets This type of analysis (consistent evolution, radius, spectrum) has yet to be successfully applied to the known hot companions Need to take care in interpretation - not just about fitting models to spectra or photometry 14

22 Challenges for Interpretting Directly Imaged Planets L HR 8799 b,c,d and 2M1207B look like extensions of L sequence T Cloudy, lower gravity & lower Teff than field L dwarfs Clouds Need to understand clouds and mixing to interpret their spectra Clouds Nature of L-T transition Ultimately water clouds 15

23 50% 75% g=10 5 cm s -2 Does L/T transition arise from partial cloudiness, varying sedimentation efficiency, or some other mechanism? GPI will probe and expand this parameter space. Partly Cloudy 1000K 16

24 Cold & Cloudy Planets {H 2 O} {MgSiO 3 } {Fe} {Al 2 O 3 } {Ca 4Ti 3 O 10 } Sun P (bar) {NH 3 } Jupiter (128 K) T (1000 K) M (3000 K) L (1800 K) T (K) 17

25 600K 300K 18

26 What will be effect of water clouds? Teff = 300 K g = 100 m sec -2 19

27 In this model NIR cloud signature mostly in J band (depends on particle size). Water cloud giants will likely show great spectral diversity depending on fractional cloud coverage and particle sizes which in turn depend on atmospheric dynamics, gravity, Teff, and metallicity. 20

28 Polarization of Thermal Emission 21

29 Cloudless atmospheres are polarized in thermal emission only in the blue Requires clouds for significant signal Oblate body low gravity fast rotation Requirements Sengupta & Marley

30 Sengupta & Marley

31 Planet Polarization Polarization (few percent at best) implies 1.5 Low gravity Fast rotation Clouds Favorable i I J Non-detection not very informative Sengupta & Marley

32 But...Assumed Homogeneous Cloud Deck Large fraction of polarized, cloudy planets may imply inhomogeneous cloud distribution. Ultimately may be a statistical argument. Polarization is interesting, but not highest priority. 25

33 Ongoing Challenges Opacities (methane, ammonia) Clouds Mixing Lots of interesting science awaits 26