People
Susanne Höfner, EXWINGS PI
Researcher, Uppsala University
My research is focused on physical properties of evolved stars, in particular dynamical processes such as pulsation and stellar winds, and the formation of stardust. To understand these phenomena, I work on developing advanced radiation-hydrodynamical models and comparing the results to observations.
More information about our research on stellar winds can be found here: Stellar Winds.
Bernd Freytag
Researcher, Uppsala University
My interest lies on dynamical processes in stellar atmospheres, but also the interior and the nearby environment of stars: surface convection, granulation, overshoot, pulsations, shock waves, mixing processes, formation and transport of dust, stellar winds. To investigate these processes, we perform 3D numerical simulations with our radiation-magneto-hydrodynamics code CO5BOLD, collaborating with a number of external observers. In Uppsala, we focus on stars on the Asymptotic Giant Branch (as, for instance, Mira) and red supergiants (like Betelgeuse). Other research concerns cool main-sequence stars including the Sun, brown dwarfs, cepheids, and white dwarfs.
Kjell Eriksson
Researcher, Uppsala University
I started my research computing stellar atmospheres (photospheres) for late-type giant stars in 1970s and was part in developing the MARCS code. Then moved to observing and modelling chromospheres also for late-type giants including carbon stars. This led to an interest in outer atmospheres and outflows from carbon stars using radio observatons of CO and other molecular species. Lately, I modelled the atmosphere plus wind structures of carbon stars using the radiation-hydrodynamic code DARWIN and the synthetic spectrum generating code COMA with the intent of producing observables mostly in the infrared region for e.g. space observatories and modern interferometers.
Joachim Wiegert
Researcher, Uppsala University
My research focusses on radiative transfer simulations in 3D through dusty environments using RADMC3D (link here). Previously, I have modelled debris discs of nearby solar-like stars and recently I moved to simulating emission and scattering from dust in circumstellar envelopes of AGB-stars. I am using results from dynamical simulations to simulate time-series SEDs and images that are compared with observed data.
Ka Tat Wong
Researcher, Uppsala University
My research focusses on high-angular-resolution observations of the circumstellar envelopes of AGB stars with (sub)millimetre interferometers, such as ALMA and NOEMA. I am also interesting in comparing the observations of molecular gas radiation with the outputs from hydrodynamical models through radiative transfer modelling.
Arief Ahmad
PhD Student, Uppsala University
I am interested in the complex interaction between convection and pulsation, alongside their roles in producing stellar winds and outflows from pulsating AGB and red giant stars. I am currently getting acquainted with the CO5BOLD code and developing tools for analyzing the output and astrophysical properties of global 3D models. One such property is the pulsation period, where I am looking into how the period, or multiple periods, of a star can be extracted from the 3D models. Further investigation then includes finding any correlation between the extracted periods and the stellar parameters taken as input for the 3D models.
Emelie Siderud
PhD Student, Uppsala University
PhD student in astrophysics specializing in stellar evolution, and with a particular interest in understanding the massive outflows of gas and dust of evolved stars. Currently working on producing and testing dust-driven wind models for asymptotic giant branch stars based on the 1D DARWIN code.