QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. NGAO- Solar System Science Cases F. Marchis (UC-Berkeley) Members: A. Bouchez (Caltech), J. Emery (NASA-Ames), K. Noll (STSCI), M. Adamkovics (UC-Berkeley) General introduction • Planetary science from the ground – Complementary with space mission (if any) – AO because need for high angular resolution – Variability & good temporal monitoring (over several years) to understand variable events (volcanism, atmosphere, resurfacing) Science Cases • A. Multiple Asteroidal Systems – A.1. 87 Sylvia - a Main-Belt multiple system – A.2. 2003 EL61 - a TNO multiple system – A.3 Size and shape (-> density?) – A.4 Spectroscopy of moonlets (origin?) • B. Titan and other Giant Planet Satellites – B.1. Titan surface and its atmsophere – B.2 Io Volcanism – Smaller Giant Planet Satellites? •C. Atmosphere of Giant Planets Minor Planets •~300,000 minor planets known •Small apparent size (largest MB-> 1 Ceres Dapp=0.7arcsec <-> “seeing” limit • Building blocks of the Solar System linked to its formation L5-Trojan Main-Belt QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. L4-Trojan Centaurs TNOs Thomas et al. 2005 What are asteroids made of? (a) Shape of NEA* Toutatis observed with radar QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Internal structure? (b) Monolith (c ) Contact Binary (d) Rubble Pile From E. Asphaug, 1999, “Survival of the weakest” * NEA= Near Earth Asteroid MB 45 Eugenia & TNO 1998WW31 Petit-Prince (Classical, 2000) Binary Asteroids (AO, 1998) A Family Portrait MB Ida and Dactyl (Galileo 1993) MB 87 Sylvia and its 2 moons NEA 2000DP107 (AO, 2005) (2002, radar) MB 90 Antiope (AO, 2001) Binary Asteroids - 85 systems known Astronomical prize for astronomers and theorists ⇒ Mass, density, formation of solar system Multiple asteroid system: 87 Sylvia •87 Sylvia was discovered in Aug, 2005. Rprimary = 143 km, Rremus= 3.5 km, Rromulus=9 km •add 2 more moonlets. 1 closer (6km) at 480 km and one smaller (1.75 km) at 1050 km QuickTime™ and a YUV420 codec decompressor QuickTime™ and a are needed to see this picture. TIFF (Uncompressed) decompressor are needed to see this picture. Simulations NIRC-2 H band •Positions is calculated based on orbital parameters •Images generated Blurred by convolution •No noise added yet (TBD) •Positions estimated by fit with Gaussian •Dynamical model to fit the orbital paramters •-> COMPARISON Simulations NGAO-R band Simulations NGAO-H band Close-up •Positions is calculated innermost moon can be seen all the time based on orbital parameters •Images generated Blurred by convolution •No noise added yet (TBD) •Positions estimated by fit with Gaussian •Dynamical model to fit the orbital paramters •-> COMPARISON (TBD) Preliminary analysis S_Romulus S_Remus S_New1 S_New2 Det. Dm Det. Dm Det. Dm Det. Dm rate Rate Rate Rate init 100% 6.00 100% 8.06 100% 6.89 100% 9.56 NIRC2-H 100% 6.5±0.2 75% 6.1±1.0 58% 5.0±1.9 20% 9.7±0.5 NGAO-H 100% 5.94±0.1 88% 8.3±0.9 76% 6.6±1.4 70% 11.1±1.4 5 NGAO-R 100% 6.02±0.0 100% 8.3±0.1 100% 6.7±1.0 100% 9.6±0.2 1 HST-R? •Detection of fainter moonlet & closer moonlet •Better photometry (size & shape) Future task Use our dynamical model to estimate the orbital elements And their accuracy + precision Will it be possible to see second order interaction such as: -Forced eccentricity due to resonance -Precession effect Work in progress…. AO Imaging of Asteroids • Directly measure size, shape, albedo, rotation – Clues to planet formation mechanisms – Collisional history of Solar System – Endogenic and exogenic processes active on individual and groups of asteroids – Complement spacecraft missions • Temporal coverage, cost effective Close-up pictures of asteroids 25143 Itokawa Cases in point – Vesta. • Imaging reveals 460 km basin – strong constraint in collisional models (e.g. Bottke et al. 2005) . .and Elektra • Dark albedo marks – endogenic or exogenic process? How many asteroids observable w/ NGAO? • MB, Troj, Cen, TNO – assume observed at perihelion and opposition • NEA – assume observed at close-approach (MOID) Populations by brightness (numbered and unnumbered asteroids) Orbital Total V < 15 15 < V < 16 < V < 17 < V < type number 16 17 18 Near Earth 3923 1666 583 622 521 Main Belt 318474 4149 9859 30246 88049 Trojan 1997 13 44 108 273 Centaur 80 1 1 2 2 TNO 1010 1 2 0 2 Other 3244 140 289 638 870 How many asteroids observable w/ NGAO? Populations by brightness (numbered asteroids only) Orbital type Total V < 15 15 < V < 16 16 < V < 17 17 < V < 18 number Near Earth 424 346 50 25 3 Main Belt 118381 4074 9537 25330 45420 Trojan 1010 13 44 108 262 Centaur 31 0 1 2 2 TNO 108 0 0 0 2 Other 483 112 151 152 54 Resolved asteroid shape • Diameters from IRAS or from H with assumed albedo • No blurring for V<15, some blurring for fainter • Require angular diameter > 2 resolution elements Resolvable asteroids in each band (numbered and unnumbered) Orbital type V R I J H K Near Earth 714 626 529 394 299 224 Main Belt 1391 1164 879 562 374 240 Trojan 13 13 13 7 1 0 Centaur 111110 TNO 333333 Other 16105110 Multiple Trans-Neptunian Object Kuiper Belt Object satellite systems • Recent detections suggest that most large KBOs may have multi- satellite systems. • 3 bright KBOs observed with Keck 2 LGS, 3 satellites were detected. • Satellite orbits give primary mass, and constrain the formation and collisional history of the Kuiper Belt 2003 EL61 A Charon-sized KBO with 2 satellites in non-coplanar orbits. (Brown et al. 2006) NGAO planetary science case A.2: A survey of KBO satellite systems K2 LGS (K') 100.0 Simulation 90.0 Give 2003 EL61 a hypothetical faint 80.0 70.0 inner satellite, and determine how 60.0 1 satellite 50.0 2 satellites many satellites would be detectable in 40.0 3 satellites a 30-minute integration, as a function 30.0 20.0 of heliocentric distance (EL61 is at 51.4 10.0 0.0 AU). 50-60 60-70 70-80 80-90 90-100 Heliocentric distance (AU) SCAO 105nm (J MCAO/MOAO 100nm (J) 100.0 100.0 90.0 90.0 80.0 80.0 70.0 70.0 60.0 1 satellite 60.0 1 satellite 50.0 2 satellites 50.0 2 satellites 40.0 3 satellites 40.0 3 satellites 30.0 30.0 20.0 20.0 10.0 10.0 0.0 0.0 50-60 60-70 70-80 80-90 90-100 50-60 60-70 70-80 80-90 90-100 Heliocentric distance (A Heliocentric distance (AU) NGAO planetary science case A.2: Preliminary conclusions and questions Conclusions: • Both NGAO systems simulated would be extremely effective! • One can use either the KBO or off-axis NGS for tip-tilt. Choice depends on AO configuration. • An MCAO/MOAO system is somewhat preferred due to better sky coverage with moderate J band Strehl (~30% is sufficient for inner satellite detection). • Nyquist-sampled J band imaging appears optimum for 100-105nm NGAO systems. Need: • RMS tip-tilt error vs. on-axis TT magnitude (simulation used only very rough estimates) • Better understanding of Strehl vs. sky coverage, for non-SCAO configurations. For example, would a 2-chanel MOAO system (science and TT star) be ideal for this science case? • …to compare apples to apples… Spectroscopy of Asteroids and their companions • Characterization of the surface composition – mafic silicate minerals (pyroxene, olivine, spinels), hydrated silicate? – C-type asteroid - what are they? – Space weathering? • Comparison moonlet vs primary for Origin – moonlet is an infant of the primary (same composition) or is a captured asteroid? Mineralogy • Silicate absorption band centered at 1 and 2 μm (Gaffey et al. 2004) -> need to be fully sampled - up to 0.7 μm •0.7 μm hydrated feature (Rivkin et al. 2004) low contrast & up to 0.6 μm Still controversial… LOW SPECTRAL RESOLUTION R~200-400 Summary Science case A • Which AO -> KPAO up to visible – But MCOA/MOAO for binary TNO (TBC) • Which instrument -> visible+NIR imaging+spectroscopy. • This AO will be the best tool for this scientific subject (no space mission scheduled, need for numerous observations,…) • Density & composition of minor planet is the key to understand the formation of the solar system Science Cases • A. Multiple Asteroidal Systems – A.1. 87 Sylvia - a Main-Belt multiple system – A.2. 2003 EL61 - a TNO multiple system – A.3 Size and shape (-> density?) – A.4 Spectroscopy of moonlets (origin?) • B. Titan and other Giant Planet Satellites – B.1. Titan surface and its atmsophere – B.2 Io Volcanism – Smaller Giant Planet Satellites? •C. Atmosphere of Giant Planets Mysterious Titan QuickTime™ and a • Satellite of Saturn - D~5150 km TIFF (Uncompressed) decompressor are needed to see this picture. • Surface mostly hidden by an opaque prebiotic atmosphere • Studied with Cassini spacecraft (4 flyby already) and Huygens lander (Jan. 2004) • Spatial resolution of global QuickTime™ and a FF (Uncompressed) decompressor are needed to see this picture. observations up to 9km in NIR QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Titan Surface and its Atmosphere • Goals: Observations of an extended object - imaging and spectroscopy of its atmosphere. Comparison with previous NGS AO systems. Illustration of the variability of solar system phenomena (volcanism, clouds) • Inputs from TCIS: Simulated short exposureﾊ On-Axis PSFs (~2-4s) (x10) at various wavelength (NOT YET DEFINED) in good seeing conditions for a bright reference (mv=8.5).