The AAVSO Program: A Resource for Variable Star Research
Stella Kafka, AAVSO
The AAVSO was formed in 1911 as a group of US-based amateur observers obtaining data in support of professional astronomy projects. Now, it has evolved into an International Organization with members and observers from both the professional and non-professional astronomical community, contributing photometry to a public photometric database of about 25,000 variable objects, and using it for research projects. As such, the AAVSO’s main claim to fame is that it successfully engages backyard Astronomers, educators, students and professional astronomers in astronomical research. I will present the main aspects of the association and how it has evolved with time to become a premium resource for variable star researchers. I will also discuss the various means that the AAVSO is using to support cutting-edge variable star science, and how it engages its members in projects building a stronger international astronomical community.
Dr. Stella Kafka, is the Director of the AAVSO (American Association of Variable Star Observers). Before her tenure at the AAVSO, Dr Kafka held positions at CTIO, Spitzer Science center/Caltech, Carnegie Institution of Washington/DTM and AIP Publishing. The AAVSO is an international non-profit organization of variable star observers whose mission is to enable anyone, anywhere, to participate in scientific discovery through variable star astronomy.
Charting the Outer Reaches of Exoplanetary Systems: Wide-Separation Giant Planet Demographics with Direct Imaging
Eric Nielsen, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University
Over the past decade, the combination of advances in adaptive optics, coronagraphy, and data processing has enabled the direct detection and characterization of giant exoplanets orbiting young, nearby stars. In addition to the wealth of information about exoplanetary atmospheres we obtain from spectroscopy of directly imaged planets, the demographics of these wide-separation planets allow us to directly test theories of planet formation, probing the outer planetary systems compared to transit and radial velocity techniques. In this talk I will present results from the Gemini Planet Imager Exoplanet Survey (GPIES), which surveyed 521 nearby stars for giant planet and brown dwarf companions orbiting beyond 5 AU, and is one of the largest, deepest direct imaging searches for exoplanets every conducted. The overall occurrence rate of substellar companions, and trends with companion mass, semi-major axis, and stellar mass are consistent with giant planets forming via core accretion, and point to different formation mechanisms for giant planets and brown dwarfs between 10 and 100 AU.
Simulating Planetesimal Formation in the Kuiper Belt and Beyond
Rixin Li, University of Arizona
A critical step in planet formation is to build super-km-sized planetesimals in protoplanetary disks. The origin and demographics of planetesimals are crucial to understanding the Solar System, circumstellar disks, and exoplanets. I will overview the current status of planetesimal formation theory. Specifically, I will present our recent simulations of planetesimal formation by the streaming instability, a mechanism to aerodynamically concentrate pebbles in protoplanetary disks. I will then discuss the connections between our numerical models and recent astronomical observations and Solar System explorations. I will explain why all planetesimals likely formed as binaries.