Astrophysics is a multidisciplinary research area. At the University of Helsinki, research focuses on interstellar matter and star formation, stellar magnetic activity, galaxy formation and evolution, and planetary science.
We study the interstellar medium and the star-formation processes, both in the Milky Way and other galaxies.
The research topics include:
- The physical and chemical properties of interstellar molecular clouds and the initial conditions of star formation. The studies use spectral line and continuum observations at far-infrared and radio wavelengths.
- The properties of interstellar dust grains and their evolution that is linked to the star-formation processes. These are studied using continuum observations of the thermal dust emission (at far-infrared wavelengths) and the light scattering (from optical to mid-infrared wavelengths) caused by the dust grains.
- Development of radiative transfer methods and the use of radiative transfer modelling to interpret line and continuum observations. Star-forming clouds are also modelled using the combination of numerical magneto-hydrodynamical simulations and radiative transfer calculations, to produce synthetic observations that are compared to real observations.
- We also develop methods for the analysis of the spectral line and continuum observations. One of the main goals is numerical efficiency (green computing), which often means the use of graphics processing units (GPUs) in the calculations.
The observations are made with the telescopes of the European Southern Observatory (e.g. the VLT and NTT optical/near-infrared telescopes and the APEX and ALMA radio telescopes) and other ground-based radio telescopes (e.g. Effelsberg, IRAM, JCMT, and TRAO). Data from space-borne instruments also play a central role. These include data from past satellite missions (e.g. the Planck, Herschel, and Spitzer satellites) and the James Webb Space Telescope (JWST).
The main topics of the research
- Photometric, spectroscopic and spectropolarimetric observations of stars at various evolutionary stages, ranging from young main-sequence stars to RS CVn type systems. The main instrument used is the high-resolution echelle spectropolarimeter SOFIN, currently located at Nordica Optical Telescope, La Palma, Spain.
- Unique spectroscopic time series, extending over 20 years, collected of various late-type stars, the last 8 years in the spectropolarimetric mode.
- Doppler and Zeeman-Doppler imaging methods used to invert the observational data into surface maps of temperature and magnetic field.
- Photometric data, with even longer time extent and better time sampling, obtained via international collaboration, and analysed with time series analysis methods developed within the group.
The main topics of the research
The research concentrates on understanding the formation and subsequent evolution of galaxies primarily using numerical methods. The main topics include:
- Formation and evolution of disk and elliptical galaxies
- The role of dark matter in galaxy formation
- Formation and evolution of supermassive black holes
- Modelling galactic stellar dynamics
- Dynamics of the interstellar medium and star formation in external galaxies
- Computational astrophysics -- numerical N-Body, SPH simulations
- Observational studies of high-redshift and local galaxies
Planetary science studies asteroids and comets, as well as regolith particles and particles in planetary atmospheres.
Research topics include the following:
- Light scattering from particles and media composed of them
- Radiative transfer in stochastic media
- Determination of asteroid trajectories and physical properties
- X-ray emission, scattering and absorption in planetary regoliths
- Physical properties of paper and paper pigments
Observation and research equipment in use
- Polarimetric observations of objects behind the planet Neptune and of comet cores
- Lunar photometry with an AMIE camera
- Astrometry and photometry of asteroids (2013–)
- ESA/BepiColombo MIXS/SIXS:
- X-ray spectrometry imaging of Mercury (2021–)
- NEOSSat & MarcoPolo-R:
- Determination of the threat of collision of near-Earth asteroids
- Scattering Laboratory:
- Measurements of light scattering and X-ray fluorescence in media composed of particles
- Spectroscopy of meteorites