Research at the Institute of Astronomy
During the late phases of their evolution, all stars loose a significant amount of material through a stellar wind or via a supernova explosion. Asymptotic Giant Branch (AGB) stars represent the late evolutionary stages of low and intermediate (M < 8 Msun) stars; red supergiant are the moremassive counterparts.
In the research domain of Asteroseismology, the interiors of pulsating stars are investigated through the analysis of their pulsation modes. This is similar to the study of earthquakes, which allows us to gain information on the interior of the Earth.
Interest in ground-based astronomical instrumentation began with the plan to build a modest but strategic instrument set at the observatory in La Palma, Canary Islands, specifically designed for long-term monitoring programmes of variability phenomena. The Mercator telescope is operational since 2001.... Concerning space instrumentation, we have played a key role in the calibration and developement of various intruments.
Binary stars are a prime source of stellar fundamental parameters, in particular of stellar masses. As such, binary stars are irreplaceable for probing models of stellar structure and evolution.
In 2009, the Institute of Astronomy made the strategic choice to add 'exoplanet' research to their activities, being a natural extension of their expertise: detailed knowledge on molecular spectroscopy, dust formation, radiative transfer, asteroseismology (of the mother star) and a deep understanding of the infrared detectors is necessary to properly calibrate the weak exoplanet signal and to interpret it in terms of the physical laws governing the exoplanet atmosphere. To boost the exoplanet research at the KU Leuven, Leen Decin, obtained in 2011 an Interdisciplinary Research Grant (IDO) of the Research Council of the Leuven University.
The interstellar medium (ISM) is an heterogeneous and diverse environment which plays a key role in the cycling of matter, which in turn is important to various physical processes pertinent to galaxy evolution. Old stars enrich the ISM with heavy elements, molecules and dust grains through strong dusty stellar winds or when they explode as supernovae [see research topic "AGB stars"]. New stars are born within dense cores in molecular clouds formed initially from the diffuse ISM [see also research topic "Stellar Evolution"].
The final evolution of low- and intermediate-mass single stars is a rapid transition from the Asymptotic Giant Branch (AGB) over the post-AGB transit towards the Planetary Nebula Phase (PN), before the stellar remnant cools down as a White Dwarf (WD). Although this scheme seems straight forward, there is no understanding from first principles of the different important physical processes that govern these evolutionary phases, especially for stars in binary systems. The quest for a deeper insight into the uncertain physics of these stars during the late-stages of stellar evolutions is ongoing.
In 1996, we engaged in a study aiming at calibrating spectrophotometrically the 'Short Wavelength Spectrometer' (SWS) on board of the ESA `Infrared Space Observatory' (ISO) using accurate theoretical infrared spectra of cool standard stars. These theoretical spectra were computed using the MARCS model-atmosphere code and the TurboSpectrum spectral synthesis codes (both of which originally developed at the University of Uppsala, Sweden). Using this methodology, we could improve the relative accuracy of the ISO/SWS to a level of 2% (with the original goal being 5%).
Research on stellar evolution at the Instituut voor Sterrenkuden focuses on stars with a dusty circumstellar environment. These include young stellar objects, where the circumstellar material is a relic of the star formation process, and evolved objects where material was ejected during previous (or sometimes current) heavy mass-loss episodes.
IvS is closely involved in the CoRoT, Kepler and GAIA space missions. CoRoT and Kepler have caused a real revolution in variable star research in general, despite their main scientific goals being exoplanet detection. The precise and uninterrupted photometric monitoring of thousands of stars required for exoplanet detection provided us with unprecedented light curves of all kinds of variable stars, most of them of unknown nature prior to these missions.