Star Talk: The Algonquin Pulsar Project

star_talk_feb “The Algonquin Pulsar Project”, with Professor Ue-Li Pen

Abstract: The Algonquin Radio Observatory (ARO), built in 1965, along with the Dominion Radio Astrophysical Observatory (DRAO) are the first to achieve long baseline interferometry (VLBI), whereby two single-dish telescopes are combined to provide the same resolution as a telescope the size of Canada.

CITA, the Dunlap Institute, and the Department of Astronomy and Astrophysics collectively have continued the Canadian VLBI tradition with a new program to conduct transnational interferometric observations of pulsars and fast radio bursts (FRBs). The former has been named “scintillometry,” whose purpose is to utilize VLBI on earth in combination with scattering in the interstellar medium (ISM) to create an effective telescope size of ~astronomical unit to study pulsars and the intervening matter between us and them. The latter could provide the first ever spatial localization of FRBs.

Pulsar VLBI is located at the Algonquin Radio Observatory, which is visited frequently for data collection. The Crab pulsar will be studied using scintillometry techniques and VLBI. To obtain better images, one would need a telescope with a larger diameter. An easy way to increase diameter was to combine the signals from multiple telescopes using them as an interferometer thus creating VLBI. The data collected at Algonquin are synced up to data collected with other telescopes across the world. The radio waves that is emitted from the pulses propagate to telescopes on earth directly and indirectly via deflections on a scattering screen in the interstellar medium in space. The different paths interfere thus causing scintillation. By observing the scintillation with multiple telescopes on Earth, it is possible to estimate the pulsar’s position with extremely high precision.

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Star Talk: The quest for 1% – the past, present and future for measuring the Hubble Constant and the expansion of the Universe

star_talk_oct “The quest for 1%: the past, present and future for measuring the Hubble Constant and the expansion of the Universe”, presented by Professor Hilding Neilson

Abstract: Almost a century ago, Edwin Hubble discovered that galaxies appear to be moving away from us and that farther galaxies moved at faster rates. This discovery revolutionized our view of the Universe and started the field of modern cosmology. Ever since, astronomers have been trying to better measure the expansion of the Universe, the Hubble constant, using numerous standard candles. In this talk, Professor Neilson will talk about the rich history of measuring the Hubble constant from some of the great arguments to the paradigm shift initiated by the results of the Hubble Space Telescope Key Project. He will conclude by discussing the future for measuring the Hubble constant to 1% precision to shed new insights into the dark matter and dark energy content of the Universe.

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Star Talk: Variable Stars – Action in the Sky

var_stars “Variable Stars: Action in the Sky”, presented by John Percy, Professor Emeritus of the Department of Astronomy & Astrophysics, and Dunlap Institute

Abstract: Stars aren’t changeless and boring. They may eclipse, pulsate (vibrate), flare, erupt, or even explode. These processes cause the stars to vary in brightness over time and, by studying these variations, we can learn about the nature, evolution, birth and death of the stars, and about the physical processes that occur within them. Variable stars help us to understand some of the most exciting and bizarre objects in the sky: exoplanets, supernovas, pulsars, quasars, gamma-ray bursts, and even black holes. I will also explain some of the ways in which Canadian astronomers, and skilled amateur astronomers, and my undergraduate research students are contributing to this research.

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Star Talk: Planets Around Expired Stars

star_talk_sep “Planets Around Expired Stars”, presented by Professor Yanqin Wu

Abstract: Professor Yanqin Wu investigates the formation and evolution of planets, both inside and outside our own Solar System. Her current attention is devoted to a recently discovered puzzle, the presence of planetary systems around white dwarf stars, stars that have lived through their lives and are cooling off quietly in their cemeteries. The observational evidences are difficult to square with our current knowledge about the extra-solar planetary systems, and perhaps a new picture is required.

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Star Talk: Exploring the Ghostly Side of Galaxies with Dragonfly

star_talk_dragonfly“Exploring the Ghostly Side of Galaxies with Dragonfly”, presented by Dr. Roberto Abraham

Abstract: Bigger telescopes are usually better telescopes…. but not always. In this talk I will explore the ghostly world of large low surface brightness structures, such as galactic stellar halos, low-surface brightness dwarf galaxies, and other exotica such as supernova light echoes. These objects are nearly undetectable with conventional telescopes, but their properties may hold the key to understanding how galaxies assemble. I will describe why finding these objects is important, and why it is so devilishly difficult.

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