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Joint seminar (12 September 2016, 11:00)

Speaker-1: Douglas N. C. Lin (University of California, Santa Cruz)

Title: "Planting seeds for gravitational wave generators around active galactic nuclei: Analog of planetary systems around massive black holes"

Abstract: Advanced LIGO event GW150914 has been attributed to the coalescence of two black holes with masses more than double that of most known stellar black holes. Formation of such stellar black holes directly through supernova explosions requires massive, metal-deficient progenitors. This requirement and their nearly equal masses may not be compatible with its occurrence in the local Universe. I consider an alternative possibility which may lead to the robust production of binary black holes with masses up to a hundred solar masses in the proximity of active galactic nuclei (AGN's). I will describe some relevant mechanisms which are analogous to the astrophysics of planet formation. I will discuss the implications of this scenario in the context of structure and evolution of AGN disks including the cause of their super solar metallicity, duty cycle of their active phase, and the rapid growth of their central massive black holes.


Speaker-2: Stella Kafka (AAVSO)

Title: "The AAVSO as a Resource for Variable Star Research"

Abstract: 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 22,000 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.

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