UCLA

Dusty debris disks act as signposts for planet formation. They represent a crucial step in the process in stellar and solar-system evolution. Near- and mid-IR observations of these disks have revealed a multitude of systems with warm (>100K) dust in the terrestrial planet formation zone. Far-IR observations can reveal whether these systems also host cold belts of dust. If the cold component exists, then collisions between cometary bodies in the cold belt may be feeding the grain population of the warm dust component. If no cold component is seen, then the observed warm dust is likely the result of a recent collision between planetary embryos in the terrestrial planet zone. We present the results of a recent Herschel survey of more than a dozen known debris disks. Eight of these disks are resolved at 70 or 100 microns, and one is resolved at 160 microns. In addition to discovering the origin of the warm dust component, we can also compare the physical disk radii (measured directly from the images of resolved disks) to the blackbody radii (inferred from a blackbody fit to the dust emission). This comparison can help us to understand important grain properties.

Helium is the second abundant element in the solar wind and is important to understand mechanisms of space weathering and solar activities. However, in-situ analysis of He is difficult in solids because of the low abundance and the extremely low ionization yield. We are currently under development of new instruments of sputtered neutral mass spectrometry and recently succeeded to measure He depth profiling from a Genesis sample exposed Solar winds.

The secular dynamical evolution of a hierarchical three body system, in which a distant third object orbits around a binary has been studied extensively, demonstrating that the inner orbit can undergo large eccentricity and inclination oscillations. It had been shown before that starting with a circular inner orbit, large mutual inclination (40 – 140 degree) can produce long timescale modulations that drive the eccentricity to extremely large values and can flip the orbit. Here, we demonstrate that starting with an almost coplanar configuration, for eccentric inner and outer orbits, the eccentricity of the inner orbit can still be excited to high values, and the orbit can flip by ~180 degree, rolling over its major axis. The ~180 degree flip criterion and the flip timescale are described by simple analytic expressions that depend on the initial orbital parameters. With tidal dissipation, this mechanism can produce counter-orbiting exo-planetary systems. In addition, we also show that this mechanism has the potential to change the stellar distribution for binary black hole systems. Furthermore, we explore the entire eccentricity and inclination parameter space to identify the underlying resonances, the chaotic regions and the regions that can excite the eccentricity and flip the orbit.

Microlensing uses the gravitational bending of light to detect exoplanets. New upgrades and new surveys have made the discovery and followup of microlensing events more efficient, transitioning the field from discovering individual planets to detecting planets en masse. I will use recent microlensing discoveries to demonstrate how microlensing complements other planet detection techniques. In addition, I will show how higher-order effects enable us to more fully characterize these planetary systems. These techniques expand the scope of microlensing to include brown dwarfs, stellar remnants, and the mass function of the inner galaxy.

Several lines of observational evidence suggest that white dwarfs receive small birth kicks due to anisotropic mass loss. If other stars possess extrasolar analogues to the Solar Oort cloud, the orbits of comets in such clouds will be scrambled by white dwarf natal kicks. Although most comets will be unbound, some will be placed on low angular momentum orbits vulnerable to sublimation or tidal disruption. The dusty debris from these comets will manifest itself as a debris disk temporarily visible around newborn white dwarfs; examples of such disks may already have been seen in the Helix Nebula, and around several other young WDs. Future observations with the James Webb Space Telescope may distinguish this hypothesis from alternatives such as a dynamically excited Kuiper Belt analogue. If interpreted as indeed being cometary in origin, the observation that >15% of young WDs possess such disks provides indirect evidence that low mass gas giants (thought necessary to produce an Oort cloud) are common in the outer regions of extrasolar planetary systems. Hydrogen abundances in the atmospheres of older white dwarfs can, if sufficiently low, also be used to place constraints on the joint parameter space of natal kicks and exo-Oort cloud models.

The Rosetta mission to comet 67P/Churyumov-Gerasimenko is producing fantastic but puzzling images of the comet. I will present these images and set them in context so as to trigger a discussion about what we are seeing.

The idea of mining the asteroids for their resources – long a dream – has become closer to reality with the advent of commercial companies set up to do exactly that: Planetary Resources and Deep Space Industries. Both companies emphasize sending swarms of cubesat-class probes out to prospect the resources of numbers of near-Earth asteroids (NEAs). How realistic are these companies’ goals? Careful analysis suggests that ore-bearing (i.e. potentially profitable) NEAs are rare and that the supporting astronomical data is limited and patchy in quality. The first phase of asteroid prospecting will have to be industrial in scale (characterizing 1000s of NEAs/year) and will be carried out by ground-based telescopes, primarily in the optical band. The observations demand large (2m – 8m) telescopes and high professional standards (0.1” or better astrometry; 0.1% photometry; sub-1% spectrophotometry). Just like geologists, applied astronomers will be in demand.