UTSC

Astronomy and Astrophysics - what’s its purpose in the society? 0. Model for freedom of thinking & cooperation 1. Understanding - solar system functioning and origin - extrasolar planets, and the place of solar system among other systems - sun-Earth connection - chaos 2. Prediction - global warming - impacts

Understanding of extrasolar and solar planetary systems through theory of their formation  Introducing extrasolar systems  Protoplanetary disks  Disk-planet interaction: resonances and torques, numerical calculations, mass buildup, migration of planets  Dusty disks in young planetary systems  Origin of structure in dusty disks

Source: P. Kalas HD107146

At the age of 1-10 Myr the primordial solar nebulae = protoplanetary disks = T Tau accretion disks undergo a metamorphosis They lose almost all H and He and after a brief period as transitional disks, become low-gas high-dustiness Beta Pictoris systems (Vega systems). Beta Pictoris A silhouette disk in Orion star-forming nebula

Prototype of Vega/beta-Pic systems

Beta Pictoris 11 micron image analysis converting observed flux to dust area (Lagage & Pantin 1994) B Pic b(?) sky?

Chemical basis for universality of exoplanets: cosmic composition (Z=0.02 = abundance of heavy elem.) cooling sequence: olivines, pyroxenes dominant, (Mg+Fe+SiO), then H 2 O

Hubble Space Telescope/ NICMOS infrared camera

HD A is a Herbig emission star >2 x solar mass, >10 x solar luminosity, Emission lines of H are double, because they come from a rotating inner gas disk. CO gas has also been found at r = 90 AU. Observations by Hubble Space Telescope (NICMOS near-IR camera). Age ~ 5 Myr transitional disk

HD 14169A disk (HST observations), gap confirmed by the new observations

n Gas-dust coupling? n Planetary perturbations? n Dust avalanches? HD A: Spiral structure detected by (Clampin et al. 2003) Advanced Camera for Surveys onboard Hubble Space Telescope

Radiation-pressure instability of opaque disks found at UTSC r r

Radial-velocity planets around normal stars

-450: Extrasolar systems predicted (Leukippos, Demokritos). Formation in disks -325 Disproved by Aristoteles 1983: First dusty disks in exoplanetary systems discovered by IRAS 1992: First exoplanets found around a millisecond pulsar (Wolszczan & Dale) 1995: Radial Velocity Planets were found around normal, nearby stars, via the Doppler spectroscopy of the host starlight, starting with Mayor & Queloz, continuing wth Marcy & Butler, et al.

Orbital radii + masses of the extrasolar planets (picture from 2003) These planets were found via Doppler spectroscopy of the host’s starlight. Precision of measurement: ~3 m/s Hot jupiters Radial migration

Marcy and Butler (2003)

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Like us? NOT REALLY Why?

Diversity of exoplanetary systems likely a result of: disk-planet interactionam?(low-medium) e planet-planet interactionam?(high) e star-planet interactioname disk breakup (fragmentation into GGP) a m e? metallicity X XXX X X

Disk-planet interaction: observation + numerics

A gap-opening body in a disk: Saturn rings, Keeler gap region (width =35 km) This new 7-km satellite of Saturn was announced 11 May To Saturn

Masset and Papaloizou (2000); Peale, Lee (2002) Some pairs of exoplanets may be caught in a 2:1 resonance

Mass flows through the gap opened by a jupiter-class exoplanet ----> Superplanets can form

Binary star on circular orbit accreting from a circumbinary disk through a gap. Surface density Log(surface density) An example of modern Godunov (Riemann solver) code: PPM VH1-PA. Mass flows through a wide and deep gap!

simulation of a Jupiter in a standard solar nebula. PPM ( Artymowicz 2004)

What permeability of gaps teaches us about our own Jupiter: - Jupiter was potentially able to grow to 5-10 m_j, if left accreting from a standard solar nebula for ~1 Myr - the most likely reason why it didn’t: the nebula was already disappearing and not enough mass was available.

Disk-planet interaction: new strange migration mode

Migration Type I : embedded in fluid Migration Type III partially open (gap) Migration Type II : in the open (gap)

Type I-III Migration of protoplanets/exoplanets n Disks repel planets: n Type I (no gap) n Type II (in a gap) n Currently THE problem is: how not to lose planetary embryos (cores) ? II I M/M_Earth Timescale Ward (1997)

Type I-III Migration of protoplanets/exoplanets n If disks repel planets: n Type I (no gap) n Type II (in a gap) n If disks attract planets: Type III n Q’s: n Which way do they migrate? n How fast? n Can the protoplanets survive? II I …....III…….. M/M_Earth Timescale

Variable-resolution PPM (Piecewise Parabolic Method) [Artymowicz 1999] Jupiter-mass planet, fixed orbit a=1, e=0. White oval = Roche lobe, radius r_L= 0.07 Corotational region out to x_CR = 0.17 from the planet disk gap (CR region)

Consider a one-sided disk (inner disk only). The rapid inward migration is OPPOSITE to the expectation based on shepherding (Lindblad resonances). Like in the well-known problem of “sinking satellites” (small satellite galaxies merging with the target disk galaxies), Corotational torques cause rapid inward sinking. (Gas is trasferred from orbits inside the perturber to the outside. To conserve angular momentum, satellite moves in.)

Now consider the opposite case of an inner hole in the disk. Unlike in the shepherding case, the planet rapidly migrates outwards. Here, the situation is an inward-outward reflection of the sinking satellite problem. Disk gas traveling on hairpin (half-horeseshoe) orbits fills the inner void and moves the planet out rapidly (type III outward migration). Lindblad resonances produce spiral waves and try to move the planet in, but lose with CR torques.

Outward migration type III of a Jupiter Inviscid disk with an inner clearing & peak density of 3 x MMSN Variable-resolution, adaptive grid (following the planet). Lagrangian PPM. Horizontal axis shows radius in the range (0.5-5) a Full range of azimuths on the vertical axis. Time in units of initial orbital period.

Edges or gradients in disks: Magnetic cavities around the star Dead zones

Summary of type-III migration n New type, sometimes extremely rapid (timescale > LRs n Direction depends on prior history, not just on disk properties. n Supersedes a much slower, standard type-II migration in disks more massive than planets n Very sensitive to disk density gradients. n Migration stops on disk features (rings, edges and/or substantial density gradients.) Such edges seem natural (dead zone boundaries, magnetospheric inner disk cavities, formation-caused radial disk structure) n Offers possibility of survival of giant planets at intermediate distances ( AU), n...and of terrestrial planets during the passage of a giant planet on its way to the star. n If type I superseded by type III then these conclusions apply to cores as well, not only giant protoplanets.

1. Early dispersal of the primordial nebula ==> no material, no mobility 2. Late formation (including Last Mohican scenario)