May 28, 2022:
"Surprises from the Expansion of the Universe"
with Dr. Adam Riess
The Hubble constant remains one of the most important parameters in the cosmological model, setting the size and age scales of the Universe. Present uncertainties in the cosmological model including the nature of dark energy, the properties of neutrinos and the scale of departures from flat geometry can be constrained by measurements of the Hubble constant made to higher precision than was possible with the first generations of Hubble Telescope instruments. A streamlined distance ladder constructed from infrared observations of Cepheids and type Ia supernovae with ruthless attention paid to systematics now provide 1.4% precision and offer the means to do much better. By steadily improving the precision and accuracy of the Hubble constant, we now see evidence for 5 sigma deviations from the standard model, referred to as LambdaCDM, and thus the exciting chance, if true, of discovering new fundamental physics such as exotic dark energy, a new relativistic particle, or a small curvature to name a few possibilities. I will review recent and expected progress, most recently based on measurements by the SH0ES Team from the Hubble Space Telescope and Gaia EDR3.
April 23, 2022:
"The discovery of pulsars – a graduate student’s tale"
with Dr. Jocelyn Bell Burnell
I will describe how pulsars were accidentally discovered and relate some instances where they were 'nearly' discovered.
March 26, 2022:
"The Last Stargazers"
with Dr. Emily Levesque
A bird that mimicked a black hole. The astronomer that discovered microwave ovens. A telescope that got shot. The science of astronomy is filled with true stories (and tall tales) of the adventures and misadventures that accompany our exploration of the universe. Join Dr. Emily Levesque, author of the critically-acclaimed popular science book The Last Stargazers, to take a behind-the-scenes tour of life as a professional astronomer. We'll learn about some of the most powerful telescopes in the world, meet the people who run them, and explore the crucial role of human curiosity in the past, present, and future of scientific discovery.
February 26, 2022:
"Variable Stars and Interacting Binary Systems in High Definition"
with Dr. Margarita Karovska
Multiwavelength sub-arcsecond resolution imaging offers extraordinary opportunities for detailed studies of many astronomical sources. These include evolved stars and interacting binaries that show significant variations of physical characteristics on time scales ranging from days to many years, even centuries (as shown for example by the AAVSO long-term monitoring of its light curves).
I will highlight results from multimission imaging with high-spatial resolution of several nearby supergiants, giants, and symbiotic interacting binaries. The high definition images are key to understanding the structure and mass transfer processes, especially of progenitors of planetary nebulae, supernovae, and including supernovae type Ia (key cosmological distance indicators). AAVSO long-term observing/monitoring has facilitated these discoveries and is crucial for planning future observations of variable stars and interacting binary systems. .
I will conclude by discussing the potential of future ultra-high angular resolution imaging, with resolution over 100 times higher than that of the HST (e.g., Stellar Imager with <0.1 milliarcsecond resolution imaging in UV-Optical), which will open unprecedented possibilities for spectral and spatial studies of a wide range of currently unresolvable astronomical sources in the Universe.
January 22, 2022:
"Star Tickling and the AAVSO"
with Dr. Jill Tarter
In 2008, Learned, Kudritzki, Pakvasa, and Zee1 suggested that an advanced technological civilization might phase modulate Cepheids and other regularly variable stars in order to create a type of Morse code that could transmit information across the galaxy. Several attempts have been made to find such modulations, but the AAVSO would appear to be the ideal organization to conduct a systematic exploration of observational records stretching over a century.