SIfA Seminars

A28 LT5 • 11:00
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Mapping stellar surfaces is an inherently degenerate inverse problem. Recent work has shown that photometric and astrometric signals each fail to recover the vast majority of surface information, particularly at smaller spatial scales, and even jointly leave most of the surface unconstrained. Reducing this degeneracy requires prior information, but conventional approaches often impose unrealistically rigid surface models. I will present recent results using simulation-based inference to recover stellar surfaces from photometric and astrometric signals, both individually and in combination. SBI encodes flexible surface priors through the training distribution rather than through hard constraints, yielding full posterior distributions rather than point estimates, without computationally costly sampling. The amortised cost of training also enables large-scale inference across stellar populations at negligible marginal cost.

A28 LT5 • 11:00
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Modern astronomy research relies on increasingly complex facilities—but the people who operate them, and the careers built around this work, remain largely invisible within traditional academic pathways.

In this talk, I will draw on my experience across multiple major observatories, including Parkes, DRAO and the SKAO, to unpack what “telescope operations” actually involves in practice, and how it evolves over the lifetime of modern observatories.

Operations is often framed as support work—but in reality, it is where many of the decisions are made that enable new astrophysical discoveries. These roles require broad expertise, scientific judgement, and systems-level thinking, and they offer a different—yet still impactful—way to contribute to astronomy research.

For early-career researchers in particular, I will discuss what telescope operations career pathways can look like in practice, what skills are valued, and why this can be a deeply rewarding (if under-recognised) career.

location • time
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Abstract: Since 2010, pioneering time-domain photometric missions (CoRoT, Kepler, and TESS) together with extreme-precision radial-velocity instruments (VLT/ESPRESSO and Keck/KPF), have revealed a rich spectrum of low-amplitude stellar variability driven by rotation, convection, and oscillations. Among these phenomena, stellar oscillations provide a powerful probe of stellar interiors, enabling unique inferences of fundamental properties and internal physics of stars. These constraints provide direct knowledge of internal composition, angular momentum transport, convection, and magnetism. These new constraints, however, also reveal significant deviations from our theoretical expectations. In this talk, I will present a few recent technical, observational, and theoretical advances enabled by these data, including applications to exoplanet host characterization, post-mass-transfer systems, and mass-loss mechanisms in red giant stars. The coming decade—driven by ongoing and forthcoming facilities such as TESS, Rubin, Roman, PLATO, and Earth2.0—will continue to revolutionize stellar, Galactic and exoplanetary science.

A28 • LT5
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Gravitational waves are emitted across a vast spectrum of frequencies. Ground-based detectors such as LIGO/Virgo/KAGRA observe relatively high-frequency waves from approximately stellar-mass compact objects, and have led to truly impressive discoveries in an otherwise dark corner of our Universe. At the other end of the spectrum, some of the most energetic interactions in the Universe — the inspirals of supermassive black hole binaries — produce a low rumbling that requires a detector of an entirely different kind. By monitoring the pulses emitted by millisecond pulsars distributed across the Milky Way, pulsar timing arrays construct a gravitational wave detector spanning thousands of light-years. In recent years, these experiments have reported mounting evidence for a gravitational wave background permeating the galaxy, opening a new window into the nanohertz gravitational wave Universe. In this talk, I will describe how pulsar timing arrays operate, what we have found so far, and the road ahead – including the MeerKAT Pulsar Timing Array, which exploits one of the world’s most sensitive radio telescopes, the international effort to combine data across global collaborations, and new analysis techniques that push the frontiers of measurement precision.