DRAO Seminar Series Fall 2017

New Views of Debris Disks with Millimeter Interferometry

David Wilner (SAO/Harvard CFA)

At least 20% of nearby main sequence stars are surrounded by disks of dusty debris from the collisional erosion of planetesimals, similar to comets in our Solar System. Since these dust-producing bodies can persist only in stable regions like belts and resonances, the locations, morphologies, and physical properties of dust in these “debris disks” provide probes of planetary system architectures and evolution. Observations at millimeter wavelengths offer a unique window, since the large grains that dominate emission at these long wavelengths trace the dust-producing planetesimals, unlike small grains seen in the optical that are rapidly redistributed by stellar radiation and winds. In this talk, I will present recent observations of debris disks at millimeter wavelengths that take advantage of the new capabilities available with ALMA, the VLA, and other radio interferometers. In particular, I will discuss tests of collisional models, and imaging disk features that relate to the presence of planets.

Remixing the Greatest Hits of the 80s (in Molecular Clouds)

Erik Rosolowsky (U. Alberta)

In the local Universe, all stars form in clouds of molecular gas. On the largest scales in galaxies, the ensemble of molecular clouds produces a simple star formation law: more molecular gas is linearly correlated with more star formation. This star formation law must emerge from behaviour of groups of individual molecular clouds. In this talk, I will present recent observations of molecular clouds and star forming regions in the Galactic Plane. I will show off new methods for untangling blended maps of molecular gas, assigning distances, and matching the results to regions of star formation. With this analysis we present a new atlas of molecular clouds in the Milky Way, highlighting large spatial dynamic range in the maps. This analysis finds good evidence that significant mass flows are essential for feeding star forming regions across the Galactic disk. Additionally, higher mass molecular clouds show evidence for increased rates of star formation, suggesting again these clouds are fed from their environment over their lifetime. The large apparent scatter in the efficiency of the star formation process can be attributed in part to viewing the effects of this mass accretion over time. I will close by highlighting the promise of future surveys with the JCMT and ALMA that will expand these approaches in our Galaxy and others.

Is Anyone Out There? SETI@home and the Breakthrough Listen Project

Dan Werthimer (Berkeley SETI)

What is the possibility of other intelligent life in the universe? Can we detect radio, infrared, or visible light signals from alien civilizations? Current and future projects searching for such signals, including the new $100-million Breakthrough Prize Foundation Listen project, may provide an answer. Dan Werthimer will describe the plans for future searches and show how new technologies are revolutionizing the search for extra-terrestrial intelligence (SETI). He will also describe the SETI@home project, which analyzes data from the world’s largest radio telescopes using desktop computers and cell phones from millions of volunteers, forming one of Earth’s most powerful supercomputers.

Radar Love: Recent Asteroid & Comet Results from Arecibo Observatory’s Planetary Radar System

Alessondra Springmann (Arizona)

Asteroids do concern me, Admiral: short of sending spacecraft to an asteroid, the best way to learn about asteroids is to zap them with radar. Arecibo Observatory in Puerto Rico is home to the world’s largest single-dish radio telescope and the most powerful planetary radar system for asteroid studies. The 305-meter diameter facility dedicates hundreds of hours a year to improving our knowledge of near-Earth asteroids and comets with planetary radar. Radar observations reveal a wide variety of asteroids shapes, surface features, and sizes, as well as asteroid moons. Important not only for robotic solar system exploration of asteroids, radar-derived asteroid shape models help us plan for potential asteroid hazard mitigation and future human exploration of asteroids. I will show recent results from the Arecibo planetary radar system and discuss the OSIRIS-REx asteroid sample return mission, launched in September 2016 to bring pieces of an ancient asteroid to Earth.

Observatory Publications 2011-2015: Productivity and Impact

Dennis Crabtree (NRC Herzberg)

Bibliometrics are increasingly used as metrics to measure the performance of individuals, institutions and countries. Refereed publications are the primary output of modern observatories. I use bibliometric techniques to analyze the performance of astronomical observatories and to explore some interesting aspects of astronomical publishing.

Science and status of the Maunakea Spectroscopic Explorer

Alan McConnachie (NRC Herzberg)

Numerous international reports have recently highlighted the need for fully dedicated, large aperture, highly multiplexed spectroscopy at a range of spectral resolutions in the OIR wavelength range. Such a facility is one of the most obvious missing links in the emerging network of international multi-wavelength, astronomy facilities, and enables science from reverberation mapping of black holes to the nucleosynthetic history of the Galaxy, and will follow-up discoveries from the optical through to the radio. While there are numerous 4m-class MOS instruments and facilities in development, along with a few 8m class MOS instruments, the only fully dedicated MOS facility that has been proposed and is in the design phase is the Maunakea Spectroscopic Explorer. I will provide an overview of the Observatory, describing the science drivers and the current design status, as well as partnership development activities and the schedule to first light.

The Canadian Astronomy Data Centre and You!

JJ Kavelaars (NRC Herzberg)

The CADC was formed in the 1980s to help meet the needs of Hubble Space Telescope observers. The plan for HST was that it would produce fully calibrated data sets that would be delivered to users in formats and modes that were unfamiliar to the community of users. The CADC aided in the delivery of that data to users and was at the forefront of innovations for delivery of HST data. Fast forward 30 years and the CADC continues to be at the fore of data archive and processing services. But we have not moved far from our optical roots. I will describe the structure of the CADC, the services we provide and a vision for the future of astronomical data processing and handling. This description will include a general outline of how the CADC is working to unify data access systems in astronomy and our hope to expand into work with radio astronomy community.

Understanding the Architecture of Planetary Systems

Samantha Lawler (NRC Herzberg)

Our Solar System is one of thousands of planetary systems that are now known. Is our Solar System typical, or unusual? Recent large surveys of the Kuiper belt can be carefully debiased, allowing us to study the true orbital structure in detail. We can use this to robustly test dynamical models of how the giant planets migrated to their current architecture early in the Solar System’s history, as well as probe the outer reaches of the Solar System for possible undiscovered massive planets. We can learn about planetesimal belts (analogous to the Kuiper belt) around other mature stars by studying debris disks, which are collisionally-generated dust belts easily observed in the infrared and submillimeter. Resolved structures in individual debris disks can reveal the presence of planets that are currently undetectable by any other technique, and the properties of debris disks may place constraints on planetary migration. Currently, planetary systems with inner planets have unexplored outer reaches, and systems with distant planets often have few or no constraints on the inner system. Observations with current and near-future telescopes such as Kepler, ALMA, GPI, JWST, and TESS will help fill in our knowledge of complete planetary systems, and help answer the question of whether or not our Solar System is a typical planetary system.

Ionization of the warm (magneto)ionized medium

Alex Hill (UBC/DRAO)

The ionization of the warm ionized medium has been a puzzle since its discovery in the 1970s. Observations suggest a power requirement that can only be explained with photoionization by O stars in the Galactic disk. I will discuss the success of models invoking supernova-driven turbulence to allow ionizing photons to travel from massive stars in the Galactic midplane to more than a kpc above the disk as part of the multi-phase interstellar medium. I will also present GMIMS observations of the Fan Region, a very large (30° by 60°) feature which dominates the sky in polarized continuum radio emission, arguing that the Fan Region is a Galactic-scale structure tracing the Galactic magnetic field, not a nearby feature as most authors have argued.