Víctor Aguirre Børsen-Koch (né Silva Aguirre), Associate Professor
Víctor’s main field of expertise is asteroseismology of main-sequence and red giant stars, and deriving accurate stellar properties with implications in a wide range of areas in astrophysics. His research interests include theoretical stellar structure and evolution, asteroseismic inference in solar-like oscillators, characterisation of exoplanet host stars and architecture of planetary systems, composite stellar populations in the Milky Way, and Galactic archaeology.
Víctor holds various leading positions in large international consortiums related to space missions such as Kepler, K2, TESS, and PLATO, as well as in large-scale ground based surveys such as APOGEE and SAGA. He is also the recipient of the Villum Young Investigators Programme grant, the Sapere Aude initiative from the Independent Research Fund Denmark, and the Aarhus University Research Foundation starting grant.
Jakob Lysgaard Rørsted (né Mosumgaard), Postdoc
Jakob’s main research interest is stellar modelling of stars showing solar-like oscillations. His primary focus is development of the BASTA pipeline, which is the statistical tool used in our research group to determine stellar parameters from grid-based modelling.
Before being employed as postdoc, he also did his PhD in the group. The research focus of his thesis was to improve the current 1D models of stellar evolution by the use of 3D hydrodynamical simulations of stellar atmospheres. Together with our collaborators at the Max Planck Institute for Astrophysics, he developed a procedure for combining the 1D and 3D models for use in stellar evolution calculations to produce better stellar models.
Jakob has made contributions to various scientific codes, including the BAyesian STellar Algorithm (BASTA), the Garching stellar evolution code (Garstec), and the Aarhus adiabatic pulsation package (Adipls). Jakob is the main administrator of the different software and computer systems used in the group.
Yixiao Zhou, Postdoc
Yixiao’s main research interest is asteroseismology and 3D stellar atmosphere modelling of solar-type stars. He has developed detailed numerical methods to quantify how solar-like oscillations are driven and damped using realistic 3D stellar surface convection simulations. Based on this information, he successfully predicted the amplitude and the frequency of maximum oscillation power for the Sun and several solar-like oscillating stars in a parameter-free way. Yixiao is currently working on applying these realistic 3D simulations to more asteroseismic and stellar evolution problems.
Camilla Clement Borre, PhD student
Camilla is interested in studying stars and how they can be used to learn more about the history of our Galaxy. Her research revolves around mapping out the merger events that happened during the Milky Way’s lifetime. She does this by examining the properties of the bright and abundant red giant stars by using data from e.g. the Gaia and APOGEE surveys to get information about their kinematics and spectroscopic signatures. With this information, she can distinguish between the stars born in the Milky Way before the merger and the stars born in the other galaxy that collided with the Milky Way. Using asteroseismology from the Kepler and K2 missions and Bayesian stellar modelling the ages of these stars can be found and a timeline for the Galactic evolutionary history created.
Luisa Fernanda Rodriguez Diaz, PhD student
Luisa’s main research interest is the behaviour of stellar convection in solar-like stars, up to red giants. She is developing new 3D stellar atmosphere models with different stellar parameters across the HR diagram, which are intended to be used for the PLATO mission.
Luisa is also interested in the implications of stellar convection when comparing with observations. She attempts to characterise the granulation noise in the detection of exoplanets via transits.
Amalie Stokholm, PhD student
Amalie’s field of interest is the disk stars in our Galaxy, the Milky Way. She uses data from the Gaia and Kepler/K2 missions along with data from a variety of large scale spectroscopic surveys to study the disk stars. Using asteroseismology and stellar modelling she is studying a large sample of targets in order to unravel the history of our Galaxy, the Milly Way.
Currently, she studies red giant stars in the disk(s) of the Milky Way and looks for patterns related to the merger history of the Galaxy.
Mark L. Winther, PhD student
Mark’s research is focused around improving models of stellar evolution for solar-like oscillators. He is mainly researching how to improve the 3D magneto-hydrodynamical simulations of stellar atmospheres, as these are key to interpret the observations of stars. This mainly revolves around optimizing the use of computational resources, by shifting the evolution from a global to a local timescale. This should not only improve the efficiency of which models can be produced, but allow the simulations to cover larger parts of the stellar atmosphere or convective envelope.
Additionally, he researches the effect of convective overshoot on the convective cores of main-sequence solar-like oscillators. This is mainly in regards to the 1D implementations of the effect, and how altering these can improve the best-fit models.
Julie Thiim Gadeberg, Master student
Julie’s work focuses on the Milky Way Halo. Due to the observational difficulties associated with it, the halo is one of the least understood components of the Milky Way; luckily, with missions such as Gaia probing further than ever, it should be possible to find vital information about its formation and evolution.
Julie will be using a combination of Gaia data and photometric analysis to determine number ratios between Blue Straggler stars and Blue Horizontal Branch stars. These ratios will be used to set mass constraints on the main ’building blocks’ of the halo.
Emanuele Spitoni, Postdoc
Emanuele’s main research interest is the Galactic Astroarchaeology using chemical evolution models.
The purpose of Galactic archaeology is to unveil the formation and evolution of our Galaxy by interpreting signatures imprinted in the observed chemical abundances and kinematics of resolved stellar populations.
He uses Bayesian analysis to fit the chemical evolution models to the data provided by the spectroscopic APOGEE survey and precise asteroseismic stellar ages. He is also interested in the modelling of the GAIA Enceladus, one of the most massive satellites accreted by the Milky Way during a major merger event.
Additionally, in the extra-galactic astronomy field, he studies scaling relations between some fundamental physical quantities, such as the mass-metallicity and the main sequence relations which characterize star-forming galaxies.
Kuldeep Verma, Postdoc
Kuldeep’s main research interests are stellar astrophysics and Galactic archaeology. He uses a variety of data from various sources: for instance, he uses asteroseismic data from the CoRoT, Kepler/K2 and TESS satellites, spectroscopic information from the APOGEE survey and kinematic data from the Gaia mission. He uses these data together with stellar evolution models and advanced statistical methods such as machine learning and Bayesian analysis to learn the structure and evolution of low-mass stars as well as to unveil the formation and evolution history of the Milky Way.
Kuldeep is member of several International consortia including NASA Kepler and TESS and ESA PLATO asteroseismic science consortium. He is also member of International Astronomical Union (IAU) and European Astronomical Society (EAS).
Tim White, Postdoc (Currently at University of Sydney)
Tim uses the most sensitive observational tools of modern stellar astrophysics to determine the properties of stars with the utmost precision. Oscillations in stars can be detected using sensitive photometric measurements, such as those made with NASA’s Kepler and K2 Missions, from which stellar properties such as radius, mass, and age can be determined using asteroseismology.
Additionally, Tim uses long-baseline optical interferometry to directly measure the sizes and effective temperatures of stars. Precise and accurate measurements of fundamental stellar properties are crucial for testing stellar models, through which we enhance our understanding of stellar structure and evolution.
Mikkel Nørup Lund, Postdoc (Currently at Stellar Astrophysics Centre, Aarhus University)
Mikkel’s main research interest is focused around the study of solar-type stars using asteroseismology. This includes the extraction of information from stellar oscillation modes for use in stellar modelling efforts, the assessment of rotation and activity, as well as the determination of the spin-orbit alignment exoplanet host stars.
Mikkel is also interested in the utilisation of photometry from space based missions such as the NASA Kepler and K2 missions for use in, for instance, asteroseismology. Mikkel is involved in the preparatory work for the upcoming NASA TESS mission, with emphasis on light curve preparation and data calibration
Ditte Slumstrup, Postdoc (Currently at ESO, Chile)
Ditte’s main research interest is optical spectroscopy of red giants. She is currently working on characterizing systematic differences in the analysis of optical spectra between different methods utilizing precise atmospheric parameters from other fields, such as asteroseismology.
Ditte is also interested in the chemical evolution and structure of the Milky Way, working with different chemical abundance trends with stellar ages.