We describe a software package called VPLanet that simulates fundamental aspects of planetary system evolution over Gyr timescales, with a focus on investigating habitable worlds. In this first version, eleven physics modules are included that model internal, atmospheric, rotational, orbital, stellar, and galactic processes. Many of these modules can be coupled to simultaneously simulate the evolution of terrestrial planets, gaseous planets, and stars. The code is validated by reproducing a selection of observations and past results. VPLanet is written in C and designed so that the user can choose the physics modules to apply to an individual object at runtime without recompiling, i.e., a single executable can simulate the diverse phenomena that are relevant to a wide range of planetary and stellar systems. This feature is enabled by matrices and vectors of function pointers that are dynamically allocated and populated based on user input. The speed and modularity of VPLanet enables large parameter sweeps and the versatility to add/remove physical phenomena to asses their importance.

We introduce a new computational technique for searching for faint moving sources in astronomical images. Starting from a maximum likelihood estimate for the probability of the detection of a source within a series of images, we develop a massively parallel algorithm for searching through candidate asteroid trajectories that utilizes Graphics Processing Units (GPU). This technique can search over 10 10 possible asteroid trajectories in stacks of the order 10-15 4K x 4K images in under a minute using a single consumer grade GPU. We apply this algorithm to data from the 2015 campaign of the High Cadence Transient Survey (HiTS) obtained with the Dark Energy Camera (DECam). We find 39 previously unknown Kuiper Belt Objects in the 150 square degrees of the survey. Comparing these asteroids to an existing model for the inclination distribution of the Kuiper Belt we demonstrate that we recover a KBO population above our detection limit consistent with previous studies. Software used in this analysis is made available as an open source package.

With Hubble Space Telescope Fine Guidance Sensor astrometry and published and previously unpublished radial velocity measures, we explore the exoplanetary system μ Arae. Our modeling of the radial velocities results in improved orbital elements for the four previously known components. Our astrometry contains no evidence for any known companion but provides upper limits for three companion masses. A final summary of all past Fine Guidance Sensor exoplanet astrometry results uncovers a bias toward small inclinations (more face-on than edge-on). This bias remains unexplained by small number statistics, modeling technique, Fine Guidance Sensor mechanical issues, or orbit modeling of noise-dominated data. A numerical analysis using our refined orbital elements suggests that planet d renders the μ Arae system dynamically unstable on a timescale of 105 yr, in broad agreement with previous work.

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