PD Stellar Irradiation Mineral Atmosphere Na, K, SiO, O 2, O gas (MgO, Al, AlO, FeO etc ) https://www.nasa.gov/topics/universe/features/rocky_planet.html / (2018.5.9) Magma Ocean
Ito et al. (2015) (HRE)
Size: exoplanets.org 10/8/2017 3000 Planetary Radius [Earth Radii] 10 1 Jupiter Neptune > Earth Mars 500 1000 1500 2000 2500 Radiative Equilibrium Temperature[K] NASA/ESA 0.01 0.1 1 Semi-Major Axis [Astronomical Units (AU)]
Rocky Vapor Atmosphere Rocky planet Volatile-rich Atmosphere Water-rich planet *
2002 Hot Jupiter Charbonneau et al. (2002) etc 2010 Hot Neptune Bean et al. (2010) etc 2016 Hot super-earth Demory et al. (2016) etc (TESS-2017 JWST-2020 ) Volatile-rich Atmospheres TESS (2018 ) or H2O+CO2 :Miller-Ricci & Fortney.2010 http://explorers.gsfc.nasa.gov /ex.html#tess GJ1214b JWST (2020 ) GJ1214b De śert et al. (2011)
HRE: Hot Rocky Exoplanet (Super-Earth) > ~1500K (volatile-free) < 0.1AU HRE Ex. CoRoT-7 b (4.8M, 1.7R, T=2500K) Kepler-78 b(1.7m, 1.2R, T=2600K) HRE
HRE Mineral Atmospheres Schaefer & Fegley, (2009) Na, O, O 2, SiO 10 bar 1500K 10 bar 3000K (Schaefer et al., 2012; Volatile-rich) Thibaut & Kristen (2011) 1D - << Y. Ito, M. Ikoma, H. Kawahara, H. Nagahara, Y. Kawashima & T. - Nakamoto (2015)
Ito et al. (2015) Hot Rocky Exoplanet (HRE < 0.1AU HRE
Pressure P vapor 1D atmospheric model (Ito et al. 2015) G-type star(t*=6000k) Stellar Irradiation Rocky vapor compositions Magma ocean Planetary Irradiation Assumptions - Planetary properties 2R earth, 10M earth, R * =R sun, T * =6000K - Magma ocean surface Volatile-free Bulk Silicate Earth (BSE) (McDonough and Sun 1995) - Gas-melt equilibrium composition MELTS model (Ghiorso & Sack 1995) CEA code (Gordon & McBride 1996) - Hydrostatic equilibrium - Local thermal equilibrium - Radiative equilibrium
dp dz = ρg dτ υ dp = κ υ g = σ υ mg z: ρ g τ σ m ( ): Toon et al., (1989) F υ + τ υ F υ τ υ = 7 4 F + υ 1 4 F υ 2π B υ (τ υ ) = 1 4 F + υ 7 4 F υ + 2π B υ (τ υ ) F υ * (τ υ ) = µ * F υ * (τ υ = 0)exp( τ υ / µ * ) ν 100 F ± F * B μ * : Unsold (1955), Gray (1976) a = (γ R +γ W ) / 4πΔυ D, Δυ D = υ 0 σ (υ ) = i, j π 1/2 e 2 g f i exp( E i / kt) i, j m e cδυ D g l exp( E l / kt) l (1 exp( hυ i, j / kt))voigt(υ υ i, j, a) v, v = (2kT c m )1/2 γ R = 0.22 10 14 / λ[nm] 2,γ W =17 C 2/5 6 v 3/5 N
MELTS & CEA: P vapor (T ground ), χ (T n, P n ) No No σ ν (T n,p n,χ) :(Toon et al., 1989) F n = F ν,n σ ν,χ, P n )dν F n =const Yes : P ground =P vapor (T ground ), χ (T n, P n )=χ n Yes σ ν (T n,p n,χ) No T n =T n +ΔT n T: P ν P vapor χ F σ n : n ground : Database HITRAN2012 : Kurucz(1992) Yes
H, C, N, S, Cl Log(Total Pressure [bar]) 0-1 -2-3 -4-5 -6-7 1500 2000 2500 3000 Temperature [K] Log (Molar fractoin) 0-1 -2-3 -4 1500 2000 2500 3000 Temperature [K] SiO O2 Na K O SiO 2 Mg MgO TiO 2 CrO Fe FeO NaO KO P Na( ), O 2, O, K, SiO etc. 10-7 - 10-1 bar (1500-3000K)
O Fe Na K T=3000K, P= 10-2 bar SiO Si O 2 Fe / Na K /FUV SiO
T eq = T p R /a Teq=1800K Teq=2000K Teq=2300K Teq=2500K Teq=3000K SiO Si + O 10 P[bar] Log P P[bar] -8 10-7 -6 10-8 10-7 10-6 Si Teq=3000K SiO Fe O 2 10-5 SiO O2 10-4 Na K 10-3 O Si -2 10-2 Fe 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 10 0 fraction Log Molar fraction K O Na 10-6 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 10 0-8 -5 Teq=1800K Molar fraction SiO Si + O -8-6 -4-2 0 Teq<2000K : () Teq>2300K : SiO FUV SiO
MELTS & CEA: P vapor (T ground ), χ (T n, P n ) No No σ ν (T n,p n,χ) :(Toon et al., 1989) F n = F ν,n σ ν,χ, P n )dν F n =const Yes : P ground =P vapor (T ground ), χ (T n, P n )=χ n Yes σ ν (T n,p n,χ) No T n =T n +ΔT n T: P ν P vapor χ F σ n : n ground : Database HITRAN2012 : Kurucz(1992) Yes
F P (λ) ( L * / L P ) P ε( λ)= L P L * R P R * T 2 F P F * λ ( ) ( λ)
/ Na, K, Fe SiO R * =R sun R p =2R earth =0.02Rsun Teq>2300K : Hot Rocky Exoplanet Na K Fe 4,10,100μm SiO
5m 10h 100pc HRE(Teq=3000K) / R * =R sun R p =2R earth =0.02Rsun Na K SiO SiO Photon noise limit S/ N = N P N * (JWST 2020 ) SiO Na K
3 Teq=2300K [ ] 1 0.1 Hot Rocky Super-Earth / Detectable Mineral Atmosphere [AU] G Teq>2300K :r=0.5% (Howard et al.2012) G :N Gstar =26(d/10pc) 3 dmax(s/n): 5m(JWST) HRE : N = rn [d (S/ N)] 3 70planets 80 HRSE Gstar max
55 Cnc e (8.1Me,2Re,0.015AU) 55 Cnc e (Mp=8.1Me, Rp=2Re, a=0.015 AU, Teq=2700K) 55 Cnc e Water planets region Hot Rocky Exoplanet region Gillon et al.(2012)
55 Cnc e (8.1Me,2Re,0.015AU) 2700K 1300K 3370 K 2240 K (μ=2-7, P>10-3 bar) 1220 K (Demory et al., 2016) (Rp/Rs) 2 ~10% (Tsiaras et al., 2016) [um] ~1Myr
55 Cnc e (8.1Me,2Re,0.015AU) (Demory et al., 2016) (Kite et al.2016) (Tsiaras et al., 2016)
Summary 背景 主星近傍の岩石惑星は 高温であるためミネラル大気を持つ 本研究の結果 1, 大気構造 温度逆転構造 Teq>2300K 2, 二次食スペクトル Na, K, SiO由来の観測可能な特徴 近い将来展望 JWSTによるミネラル大気の検出 観測的課題 大気組成 温度分布の詳細測定 理論的課題 現在 過去 進化 に対する 内部混合 大気循環 大気散逸の影響推定(システム理解)