Hunstead Workshop

Our 2025 Distinguished Hunstead Visitors (Alejandra Recio-Blanco & Patrick de Laverny, Nice Observatory) play a key role in Gaia releases, and joined us in August to discuss new science directions.

The unique features of the workshop was to focus on Galactic ecology (i.e. the interplay of gas and stars over billions of years). In gas-poor galaxies, stars tell gas how to move; in gas-rich galaxies, the reverse is true. Since all discs went through a gas-rich phase, what are the remnants of that early epoch? Do gas clouds scatter stars? Are stars ever born “hot”? Do spiral arms emerge because of gas or stars, or both? What is the origin of azimuthal abundance variations seen by Gaia? What is the role of bar formation and its subsequent evolution? What stellar processes (e.g. resonances, migration, bars, spiral arms) are altered by the presence of the gas-rich phase? These discussions were be aided by remarkable progress in simulating Milky Way “surrogate” galaxies in a controlled and/or cosmological context. There are also lessons to be learned from local galaxy surveys that target Milky Way “analogues.” This meeting focused predominantly on the science of postdocs and PhD students.

Workshop Slides

Workshop recordings (Note: Monday did not have any audio due to technical glitch)

The stellar structure and evolution code Modules for Experiments in Stellar Astrophysics (MESA) has played a pivotal role in making the study of stellar structure and evolution readily accessible to the broad astronomy community. It was identified as a key software tool for astronomy in the 2020 U.S. Decadal Survey and has “seeped into the foundation of research and education efforts and have given rise to an immense amount of new research across multiple subfields of astrophysics,” as quoted in the 2021 Beatrice M. Tinsley Prize awarded to the first MESA developer, Bill Paxton, by the American Astronomical Society. Since 2012, annual MESA schools have been organised to teach new users and the next generation of astrophysicists and MESA developers how to use the code. In June 2024, the MESA school was brought to Australia for the first time under the name MESA Down Under, with the intent of making the school more accessible to students and early career researchers in Australia who constituted 40% of the 39 participants of the school. The 21 invited international lecturers and teaching assistants participating in the school provided both lectures and hands-on exercises on the basics of the code and a variety of example science applications. The high teaching assistant to student ratio (1:3) provided an optimal learning environment for the students, ensuring that they could easily get help and ask questions if they encountered any issues.

MESA Down Under Participants

MESA Workshop Session

Invited Speaker – Prof. Jan Eldridge

The highlights were:

• Invited speaker Marshall Perrin’s talk “Imaging Planetary Systems with JWST”
• Sergio Leon-Saval’s talk (and demo!) about the applications of photonic lanterns for the field.
• Michele Bannister’s planetary science talk delivered from New Zealand.

Other talks featured stellar activity and rotation, asteroseismology, stellar interior models, star-planet tidal evolution, stellar and planet mapping, polarimetry of circumstellar environments, atmospheric chemistry of Hot Jupiters, evaporating atmospheres, disk kinematics, exokuiper belts, transits photometry to learn about both the planet and the star, astrometry, software, astrophotonics, and new missions and facilities— like the TOLIMAN satellite currently under development to perform interferometric astrometry on the nearest star system to hunt for planets.

Above: Sergio Leon-Saval presenting on the power and promise of photonic lanterns

Left: The in-person participants represented Australian institutions University of Sydney, Macquarie University, the University of New South Wales, Australian National University, Monash University, the University of Newcastle, the University of Queensland, the University of Southern Queensland, Western Sydney University, and Sydney Observatory.

MAGPI team members and representatives from relevant surveys and theoretical simulations also joined our productive 4-day meeting. Twenty-three people attended (virtually) from Australia and Europe to discuss the survey status, science updates and took part in strategic workshops, including various synergies with other groups.

Intensive 2-hour sessions were held each day. These were recorded and posted on the internal wiki for those who were unable to join live. Participants were encouraged to turn on their camera when they were speaking to allow for a more personal experience. As this was a “hands-on” workshop, participants came up with innovative ways to collaborate remotely. Tools like Slack, GitHub, Zoom, cloud storage and virtual desktops were amongst the tools that made the meeting a success. Feedback from all involved was overwhelmingly positive.

As the event was originally planned face-to-face, we would like to thank the Hunstead Gift for Astrophysics for their generous support, although we did not incur any costs.

Large new IFS Galaxy Surveys allow for a more detailed insight in the dynamical properties of galaxies than ever before. IFS instruments such as VLT-MUSE, AAT-SAMI, and MaNGA are now intensively used by the Australian community to understand how galaxies build up their mass and angular momentum over time. At the same time, there has been a revolution in surveying the Milky Way with ESA-Gaia, GALAH and APOGEE, resulting in an extraordinary number of recent publications on the dynamical properties of our own Galaxy.

Dynamical models of galaxies are crucial for interpreting all these stellar kinematic measurements, but fitting these models still requires a significant amount of effort and expertise. This workshop is aimed at making dynamical fitting and modelling more accessible to the Galactic and extragalactic community.