University of Washington

ASTRONOMY DEPARTMENT

Just as an archaeologist explores the origins of human civilization by analyzing the remains of ancient settlements, a planetary scientist may explore the origins of solar systems by investigating the remains of bygone protoplanetary disks. Here I show how my interdisciplinary research involving both numerical simulations of protostellar disks and spectroscopy of planet hosts has yielded an emerging map of how, when and where planets form in the Galaxy. I begin by discussing the newly discovered mineralogical bottleneck in forming the planet species that dominates the set of known planets--the species that grows "bottom-up" from colliding planetesimals on close-in orbits. I then move to a second species of planet--that which forms via "top-down" collapse of a protostellar disk--and present evidence that newly formed such planets await discovery in the wide inner cavities that populate a subset of accreting protostellar disks. I close with a discussion of how the dominant species of forming planet may have changed during the Milky Way's history due to Galactic chemical evolution and reveal future plans for investigating changes in planet formation across cosmic time.

Small planets that are dynamically interacting with larger planets can get lost in the Kepler data since the transits are shallow and quasi-periodic. These are some of the most valuable planets as they are similar in size to Earth, and the dynamical interaction enables a measurement of their mass and radius, and hence density. I will describe a new technique for finding these planets, the QATS algorithm, and the first results from applying it to Kepler data, including a fascinating new planetary system.

The cause of the sunspot cycle remains as one of the major mysteries of nature. While the material motions of the electrically charged particles of the solar plasma generate the basic magnetic field, just how this becomes organized into a quasi-periodic phenomenon has resisted satisfactory explanation. Since sunspots are at the root of the space weather that is an increasing concern as humanity becomes more dependent on technology, it is of considerable societal as well as scientific importance to understand the dynamo mechanism. All dynamo theories incorporate some concept of the bulk large-scale motions of the plasma inside the Sun. Prior to the advent of helioseismology

NASA's Kepler Space Telescope uses photometry to detect dimming due to transits of small planets in front of their stars. It has found ~2300 planet candidates and ~365 systems of more than one candidate, an extraordinary dataset for studying the orbital architectures and dynamics of planetary systems. Regarding their architecture, we find their orbits to be nearly coplanar, with interesting enhancements near resonances. These traits are shared by planets and satellites in the Solar System, and point to the formation and evolution of planets in circumstellar disks. Regarding their dynamics, we are confirming these candidate systems by showing how interplanetary gravitational perturbations cause observed changes in orbital periods. Finally, the transit technique is now finding planets orbiting external to eclipsing binaries, a region largely inaccessible to Doppler measurements and full of theoretical problems for planet formation.

The Galaxy Zoo project has provided detailed morphological classifications for 250,000 galaxies drawn from the Sloan Digital Sky Survey. Project principal investigator Chris Lintott will outline how these results can be used to constrain the influence of mergers and of AGN feedback on the local galaxy population and to investigate the impact of bars on galaxy properties. The talk will also cover the discovery of unusual systems, a significant advantage of human classification, ranging from star-forming dwarf galaxies to AGN-ionized clouds, to bulgeless galaxies.

Three years ago, NASA launched a space telescope with the sole purpose of finding exoplanets, planets orbiting other suns. To date, the Kepler mission has discovered over 2000 exoplanets, many in multiple planet systems, and hundreds of which are near the size of the Earth. After a brief romp through some highlights of exoplanets, I will discuss some of the details of data and data reduction and examples of Kepler's interesting results on stars. Kepler photometry is over 100 times the precision of ground-based observations. Combined with its essentially continuous time coverage, these data provide a unique and spectacular data set for astronomy. Some specific examples will be discussed as well as highlights of the general results of the astrophysics obtained to date and planned in the extended mission. I will then explore the wide variety of exoplanets discovered and learn a bit about the stars which host these alien worlds. Our Earth has a number of properties and conditions which enable life to exist. We will explore what conditions are thought to be required for life as we know it, and discuss the exoplanets found so far which might meet our habitability criteria. Are other worlds like our Earth out there? We will see that the answer is, so far, a strong maybe. Ways in which you can get involved will be discussed.

Recent infrared observations, particularly from the Spitzer Space Telescope and Wide-Field Infrared Survey Explorer, of white dwarfs, cataclysmic variables and other interacting compact binaries, have revealed the unexpected presence of dust in many systems. In the case of single WDs, the dust points a finger at the post-main sequence survival of planetary systems and offers an opportunity to explore the chemical composition of extrasolar planetary material. In the case of CVs, the dust offers constraints on our understanding of the processes of mass transfer and accretion. In both cases, the discovery of dust provides a valuable reminder that even objects which have been extensively studied, and were thought to be relatively uncomplicated and well understood, can surprise us with the unexpected. I will review the discovery, properties, and implications of dust around white dwarfs and cataclysmic variables.

With recent large photometric and spectroscopic surveys and new instrumentation on the Hubble Space Telescope, it is now finally possible to study galaxies in a systematic way at earlier times and directly witness how the relations between spatial structure, stellar population, stellar mass, and environment change with redshift. Until very recently, these studies were hampered by the small sizes of spectroscopic galaxy samples, whereas much larger photometric samples lack the required spectroscopic information. I will discuss a novel approach, that makes use of medium-band photometry to perform detailed ``spectroscopic'' studies of ~3500 galaxies at 0.5

Supermassive binary black holes (masses of order 1 million to 1 billion solar masses and separations less than 1 pc) are predicted to be an inevitable late stage in the evolution of galaxy mergers. Such binaries have also been invoked as explanations of the formation of the cores of elliptical galaxies following a merger and the mass deficits therein, the apparent precession of radio jets, and the formation of X-shaped radio sources and they are predicted to be prime sources of gravitational waves. Yet, they remain elusive. After a historical introduction, I will describe a systematic search for such objects using the SDSS spectroscopic database and the followup observations of the initial candidates. I will present the first results from this search and discuss critical tests of the methodology as well as plans for future work.

2012 AAS Doggett Prize Lecture, 1st given at the Austin AAS meeting.

I will present a summary the weak lensing studies performed by the CFHTLenS team on the Canada France Hawaii Telescope Legacy Survey over the past 3 years. CFHTLenS reanalysed the whole CFHTLS survey from scratch and came up with a much better control and understanding of the residual systematics. I will present preliminary results on galaxy-galaxy lensing, cluster lensing, cosmic lensing, and early modified gravity work. Our work on systematics demonstrates that future wide field surveys designed to do lensing will be capable of constraining the matter distribution with unprecedented precision.