16:00 Prof Mike Lockwood (President)
Welcome and Announcements
16:05 Prof. Pilar Ruiz Lapuente (Instituto de Física Fundamental, Madrid)
‘What Type Ia supernovae are telling us about our Universe’
In this talk, I would like to address the most recent developments in our understanding of the Universe coming from the cosmological use of Type Ia supernovae (SNe Ia). The observation that the expansion rate of the Universe is currently accelerating is one of the most profound discoveries in modern astrophysics. The first direct evidence of this phenomenon was provided around twenty five years ago by high-redshift SNe Ia. The cause of such acceleration was named ''dark energy''. Nowadays, just some months ago, new analyses from SNe Ia seem to show what dark energy may be. I will discuss the state of this important question.
SNe Ia are also at the center of another cosmological debate: that of the present value of the expansion rate of the Universe, the Hubble constant, H0. The disagreement of the value of H0 measured from the Cosmic Microwave Background (CMB) by the Planck satellite and that from cosmic distance indicators such as Cepheids is called the Hubble Tension. I will explain how this is becoming a priority in present day cosmology and how it is being addressed with approaches involving SNe Ia. A conclusive answer to the question in debate is expected to come soon.
Prof. Pilar Ruiz Lapuente, presently Research Professor at the Instituto de Física Fundamental (CSIC, Madrid) and Visiting Professor at the Institute of Cosmos Sciences (University of Barcelona). Previously, graduate work in Garching (ESO) and postdoctoral positions in Paris at the Institute of Astrophysics in Paris (IAP) and at the Harvard-Smithsonian Center for Astrophysics. First tenured position as Associate Professor at the University of Barcelona. Participated, as a member of the Supernova Cosmology Project, in the discovery of the accelerated expansión of the Universe, for which she has shared the Gruber Cosmology Prize in 2007 and the Breakthrough Prize in Fundamental Physics in 2015. Previously, she was awarded the Distinction for Research from the Government of Catalonia (2002).
Member of the Academia Europaea since 2013.
Editor of two books on Type Ia supernovae and on dark energy and author of three popular books on the expansión of the Universe and on philosophical questions relative to Physics and Cosmology. At present, also with the SCP, she has found indications that the dark energy responsible for the accelerated expansión of the Universe is likely not the cosmological constant. She is also working on the Hubble Tension.
16:30 Dr Or Graur (University of Portsmouth)
‘Old Dogs, New Tricks: Late-time observations of Type Ia supernovae with the Hubble Space Telescope’
Type Ia supernovae (SNe Ia) are famously used to measure distances to faraway galaxies and, in turn, constrain cosmology. However, we still do not know exactly what types of star systems explode as these supernovae or how the explosions occur. Most SNe Ia are only observed for several weeks before they become too faint for most telescopes. Over the last ten years, late-time observations with the Hubble Space Telescope 800-2000 days post explosion have revealed fresh insights into the physics of these SNe. In my talk, I will summarize the discoveries of the last ten years (including a year-long near-infrared plateau!) and discuss their impact on our understanding of these stellar explosions.
Dr Or Graur is an associate professor of astrophysics at the University of Portsmouth's Institute of Cosmology and Gravitation, a research associate at the American Museum of Natural History, and an honorary associate professor at University College London (UCL). He conducts observational studies of supernovae and tidal disruption events (luminous flares caused by stars ripped apart and swallowed by supermassive black holes) as well as cultural studies of the mythology of the Milky Way. His popular science books include Supernova (MIT Press, 2022) and Galaxies (MIT Press, 2024).
16:55 George Darwin Lecture: Prof. Chiaki Kobayashi (University of Hertforshire)
‘The origin of Elements in the Universe’
When the universe started with the Big Bang 13.8 billion years ago, only light elements such as hydrogen and helium were produced. Carbon and heavier elements that matter to human beings and modern technology were instead created inside stars. Computer simulations allow us to predict the complex history of the Universe starting from the formation of stars, the production of elements, and the evolution of the element distribution in galaxies. These theoretical predictions have been tested with detailed observations of stars in the Milky Way. Thanks to the James Webb Space Telescope it is now also possible to study elemental abundances in very early galaxies, which has brought a surprise, that might also be a clue to understanding the origin of elements in the early Universe.
Professor Chiaki Kobayashi is an internationally recognised leader in the field of chemical evolution of galaxies, and a pioneer in the study of the origin of the elements - a subject which bridges nuclear physics and astrophysics. She was awarded a PhD from the University of Tokyo, Japan, in 2002, and has worked in Germany, Australia, and the UK. As well as running large-scale computer simulations of galaxies, she is also involved in a number of observational surveys, with a particular focus on elemental abundances. She is well known for having created an "astronomer's version" of the Periodic Table.
17:55 Closing Remarks
18:00 Drinks RAS, Burlington House
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