290 likes | 297 Views
Are there Planets outside the Solar System ?.
E N D
Are there Planets outside the Solar System ? • First answer : 1992 Discovery of the first Extra-Solar Planet around the pulsar PSR1257+12 (Wolszczan &Frail) • Are there Planets moving around other Sun-like stars ?
The EXO Planet:51 Peg b • Mass: M sin i = 0.468 m_Jup • semi-major axis: a = 0.052 AU • period: p = 4.23 days • eccentricity: e = 0 • a of Mercury: 0.387 AU Discovered by: Michel Mayor Didier Queloz
Status of Observations • 292 Extra-solar planetary systems • 337 Planets near other solar-type stars • 33 Mulitple planetary systems • 43 Planets in binaries
Multi-planetary systems • Binaries • Single Star and Single Planetary Systems
Interesting Questions • How frequent are other planetary systems ? • Are they like our Solar System (no. of planets, masses, radii, albedos, orbital paramenters , …. ) • What type of environments do they have? (atmospheres, magnetosphere, rings, … ) • How do they form and evolve ? • How do these features depend on the type of the central star (mass, chemical composition, age, binarity, … ) ?
55 Cancri 5 Planeten bei 55 Cnc: 55Cnc d -- the only known Jupiter-like planet in Jupiter-distance Binary: a_binary= 1000 AU
Extra-solare Planeten ca. 130 Planeten entdeckt massereich (~Mjup) enge Umlaufbahnen Radialgeschwindigkeits- messungen
Facts about Extra-Solar Planetary Systems: • Only 28% of the detected planets have masses < 1 Jupitermass • About 33% of the planets are closer to the host-star than Mercury to the Sun • Nearly 60% have eccentricities > 0.2 • And even 40% have eccentricities > 0.3
Distribution of the detected Extra-Solar Planets Mercury Earth Mars Venus Jupiter
M K Lifetime G A F Temperature Target Stars for Darwin/TPF 10 pc 315 stars
Sources of uncertainty in parameter fits: • the unknown value of the orbital line-of-sight inclination i allows us to determine from radial velocities measurements only the lower limit of planetary masses; • the relative inclination irbetween planetary orbital planes is usually unknown. • In most of the mulitple-planet systems, the strong dynamical interactions between planets makes planetary orbital parameters found – using standard two-body keplerian fits – unreliable (cf. Eric Bois) All these leave us a substantial available parameter space to be explored in order to exclude the initial conditions which lead to dynamically unstable configurations
Major catastrophe in less than 100000 years (S. Ferraz-Mello, 2004)
Numerical Methods Chaos Indicators: Fast Lyapunov Indicator (FLI) C. Froeschle,R.Gonczi, E. Lega (1996) MEGNO RLI Helicity Angle LCE • Long-term numerical integration: • Stability-Criterion: • No close encounters within theHill‘ sphere • (i)Escape time • (ii) Study of the eccentricity:maximum eccentricity
Multi-planetary systems • Binaries • Single Star and Single Planetary Systems
OGLE 06-109L Planet b: (0.71 +/-0.08 MJ) a=2.3 +/-0.2 AU e= ? P = 1825 (+/- 365) d Planet c: (0.27 +/- 0.03 MJ) a = 4.6 (+/-0.5) AU e = 0.11 i = 59 deg P = 5100 (+/-730) d
www.univie.ac.at/adg/exostab/ • ExoStab • appropriate for single-star single-planet system • Stability of an additional planet • Stability of the habitable zone (HZ) • Stability of an additional planet with repect to the HZ
Results of the Exocatalogue (Sandor et al., 2007)
The EXOCATALOGUE: http://www.univie.ac.at/adg/ Details: Sándor, Zs., Süli, A., Érdi, B., Pilat-Lohinger, E. and Dvorak, R.: "A Stability Catalogue of the Habitable zones in Extrasolar Planetary Systems", Monthly Notices of the Royal Astronomical Society (MNRAS), 2006
Habitable Zone • Zone around a star where liquid water can exist on the surface of a terrestial-like planet • This zone depends on: • the spectraltype , the mass , the age, …. of the star • the orbit of the planet • the mass, the composition, the atmosphere , ……of the planet • the parameters of other planets in this system (mass, orbit, …)
Size of the habitable zone of a planetary system based onthe definition given by Kasting et al. (1993).
Types of Habitable Zones: • Hot-Jupiter type • (2) Solar system type • (3)+(4) giant planet type: habitable moon • or trojan planet
Stability maps Inner region (Solar system type) Outer region (Hot-Jupiter-type)
Computations distance star-planet: 1 AU variation of - a_tp:[0.1,0.9] [1.1,4] AU - e_gp: 0 – 0.5 - M_gp: 0 and 180 deg - M_tp: [0, 315] deg Dynamical model: restricted 3 body problem • Methods: • Chaos Indicator: • - FLI (Fast Lyapunov) • - RLI (Relative Lyapunov) • (ii) Long-term computations • - e-max
How to use the catalogue HD114729: m_p=0.82 [Mjup] (0.93 [Msun])a_p= 2.08 AU e_p=0.31 m=0.001 HZ: 0.7 – 1.3 AU
m = 0.005 HD10697: m_p= 6.12 [Mjup] (1.15 Msun) a_p = 2.13 AU e_p = 0.11 HZ: 0.85 – 1.65 AU
پایگاه پاورپوینت ایرانwww.txtzoom.comبانک اطلاعات هوشمند پاورپوینت