Hanindyo Kuncarayakti and colleagues simulate supernova explosions

Let’s first allow our researcher to introduce himself:

“I am a docent and Research Council of Finland Fellow at the University of Turku, Finland, and an astronomer studying the death events of stars, known as supernovae.”

Supernovae are also the topic of his collaboration project.

“These events are gigantic explosions of stars many times heavier than our Sun, resulting in blindingly bright celestial objects hundreds of billions of times brighter than the Sun. Our collaboration aims to simulate the stellar material launched by such explosions at speeds of more than 30,000,000 km/h, crashing into nearby gas surrounding the exploding star (called circumstellar medium/CSM), in order to understand the gas interplay and radiative properties of the interaction.”

A large team working together

Dr. Kuncarayakti’s project engages multiple people from the University of Turku, Finland, and Japanese institutions.

“Our team at the University of Turku, which includes Professor Seppo Mattila and Postdoctoral Fellow Takashi Nagao, is collaborating with a team from Japan with members from several institutions: Professor Keiichi Maeda (Kyoto University), Assistant Professor Akihiro Suzuki (University of Tokyo) and Assistant Professor Takashi Moriya (National Astronomical Observatory of Japan). In addition, the collaboration contains a number of graduate students, some of whom are likely to be involved in this project.”

The collaboration itself has already existed for the past several years, where they’ve conducted common research on various time-domain astronomy and supernova-related topics, combining observational data analysis and theoretical calculations. The project presented here was just one of the topics intensively discussed on the agenda of a week-long joint workshop organized in Turku in November 2023.

“In this project, we are taking on radiation-hydrodynamic modelling of supernovae interacting with CSM. This is a very exciting and important topic nowadays due to the fact that we are now discovering an increasing number of such interacting supernovae with large diversity, and due to the question of how these massive stars form such CSM prior to their deaths as supernovae. We realised that studying the radiative properties of these objects, taking into account the multi-dimensional geometry of the gas distribution, will help our understanding of the varieties of the events and their observational properties.”

LUMI boosts competitiveness and knowledge transfer

Dr. Kuncarayakti’s project uses LUMI to simulate the supernova explosion and interaction, which requires significant computational power.

“The simulations involve solving hydrodynamics equations to trace the movements of the shockwaves in the gas, and as the gas expands and develops density variations, an adaptive mesh approach is employed. Furthermore, these simulations are done in 2 and 3 dimensions (in addition to 1-D), taking into account geometrical effects of the gas and coupled with subsequent radiative transfer calculations to derive the observables, which can then be compared with observational data from the telescopes. With such a demanding task, the power of LUMI as one of the best supercomputers in the world is indispensable.”

However, Dr. Kuncarayakti also sees other benefits to Finland for hosting a top-class supercomputer, aside from pure computing power:

“Such a research infrastructure without doubt boosts Finland’s competitiveness on the global stage and the attractiveness of Finnish researchers as reliable research partners. Working with international partners and including students in such endeavours promotes knowledge and technology transfer beneficial for the nation’s development in human resources in research.”

Pihla Kauranen & Maari Alanko & Elisa Halonen

Illustration: This artist’s impression shows dust forming in the environment around a supernova explosion. Credit: ESO/M. Kornmesser.