Stellar Close-Ups: Measuring the True Size and Shape of Stars

Stars appear as mere points of light in the night sky, even through powerful optical telescopes. So how can we possibly know how big they truly are, or even what shape they might be? Measurements are vital for understanding stellar physics and testing evolutionary models when combined with known stellar distances, photometry and spectroscopy.
Our Earth's turbulent atmosphere typically blurs starlight, preventing ground-based telescopes from measuring the true angular sizes of stars. While space telescopes avoid atmospheric blurring, even they cannot resolve the disks of most nearby stars.
This talk explores optical interferometry, which combines light from multiple telescopes to bypass atmospheric blurring and achieve ultra-high resolution (sharp enough to spot a pizza on the Moon). Tonight’s discussion will include how stellar angular diameters can be used to find stellar radius and temperature, and crucially, how it reveals the distorted shapes of fast-rotating stars, offering unique insights into their physics.

Dr Vicente Maestro

Dr Vicente Maestro is an astrophysicist with a diverse background. He holds Master's degrees in Fundamental Physics (University of Seville, 2001) and Astrophysics (University of Granada, 2005), where his thesis focused on Planetary Nebulae. After a period working in Bayesian Inference for a known soft drinks brand, he migrated to Australia and earned his PhD in Astrophysics from the University of Sydney in 2014, specializing in determining fundamental properties of hot stars (primarily main sequence spectral types B and A) using optical interferometry, photometry and spectroscopy, with key data obtained using the instrument PAVO at the CHARA Observatory (Mt Wilson, California, USA). Following his time in academia he has worked in the financial sector (Credit Risk Modelling).
Dr Maestro has recently returned to his passion for astrophysics and is a member of SASI.