For solar system objects the detection and astrometric observations of asteroids with the Uccle Schmidt telescope equipped with a CCD camera is now limited, but the observations of the mutual phenomena (occultations, eclipses ...) of satellites of the planets, and, whenever possible, of occultations of stars by asteroids are continued. The expertise gained in the study of the minor planets is nowadays used in the data processing of space projects as e.g. the Gaia satellite.
Since understanding the structure
and evolution of stars remains one of the great challenges of astronomy, stellar
astronomy is a main research topic of the service. The interiors of the stars,
but also their immediate surroundings are a unique laboratory of extreme
physical and chemical processes. The study of stars in multiple systems makes
it possible to determine basic parameters of stars and contributes to a better
understanding of the star evolution. The study of variability in stars contributes
as well and makes it possible to derive more properties of the interior of
In this context, ssAA scientists
are studying a number of types of stellar objects, such as the very massive
stars, because their loss of mass through stellar winds and their rapid life
cycle has important implications on galactic scale. Very interesting objects
are binaries with colliding stellar winds, where one tries to model the
observed structures and to understand the underlying physical processes. For
this purpose e.g. the JVLA (Karl G. Jansky Very Large Array, New Mexico, USA) is
used to monitor the variations in radio flux.
For stars of intermediate mass
the late stages of evolution are studied, particularly the (post-)AGB
(Asymptotic Giant Branch) stars and planetary nebulæ, because their study
provides important insights into stellar evolution and the physical processes
responsible for the mass loss of the stars and the ionization of the planetary
nebulæ. The astronomers of the ssAA are involved in various projects to study
the properties of the substance and the molecules in (post-) AGB stars,
planetary nebulæ and interstellar matter in general. They use data of the ESA
Herschel satellite, which was launched in May 2009. A major program was the
observation program MESS (Mass loss from Evolved Stars) with 300 hours of
guaranteed observing time in which different classes of evolved stars were
observed: AGB stars to planetary nebulæ, and Wolf-Rayet stars to young
supernova remnants. The observations are completed with data from the ground,
e.g. from ALMA, the Atacama Large Millimeter/submillimeter Array of ESO
(Chile). Planetary nebulæ are also possible cradles of molecules.
All of this is done with the
principal purpose of a better understanding of the process of mass loss and the
formation of dust. The distribution of the dust, its temperature, and the
interaction of the disk with the interstellar matter is determined on the basis
of images, the physical properties of the atoms and molecules on the basis of
spectra. To theoretically interpret the observations the researchers make, among other
tools, use of the photoionization code Cloudy, co-developed at the ROB.
Very fast stellar evolution is observed in
a unique object, of which a very late thermal pulse was observed in 1996. It is
studied by members of the ssAA with the VLT (Very Large Telescope, ESO, Chile) and ALMA.
Stellar systems are studied,
because their common distance and age provides basic information that is not
easily accessible for isolated stars. In this context also the "public
survey" project VMC (VISTA Magellanic Cloud) can be mentioned. It is part of
the very large programs of the telescope VISTA (Visible and Infrared Survey
Telescope for Astronomy) at ESO. The ROB researchers involved are especially
interested in the observations of AGB stars (Asymptotic Giant Branch) because
they belong to the aforementioned evolved stars, this time even beyond our
galaxy, namely in the Magellanic Clouds.
Another important survey is the Gaia-ESO Survey, which received 300 nights of observations with the
FLAMES instrument on the VLT (UT2) to record spectra of 100 000 stars scattered
throughout the galaxy. Specifically interesting for ssAA purposes are the
Gaia-ESO Survey observations of massive stars in clusters.
Double and multiple stars receive
extra attention within the service. The study of these objects provides
valuable information about star masses, one of the most fundamental properties
of stars. With direct observations or interferometry physical and dynamic
characteristics of components are studied. Spectroscopic and eclipsing
binaries, which allow to determine exact masses and radii of stars are studied
by almost all members of the service.
Further research is done in the
field of asteroseismology. This research domain refers to the study of the
internal structure of variable stars through the interpretation of observed
stellar oscillations. For this, the light and spectral variations of variable
stars, mainly main sequence pulsators, are observed and studied in detail. Special
attention is given to the study of variable components of double and multiple
Another topic of research work is about stellar rotation and how this rotation influences the physics, evolution, and spectrum of stars.
Observations come or came from
satellites (CoRoT, Kepler, Herschel, Gaia ...) and from ground-based
observatories all over the world (ESO, Chile; LAMOST, China; …), with a
substantial contribution from the HERMES spectrograph of the Mercator telescope at La Palma (Spain). The observation station in Humain (HOACS), where telescopes equipped with CCD cameras are available, plays also a role here.
In a broader context, all kind of variable objects (e.g. eclipsing binaries, …) are studied and algorithms and techniques to detect and characterize variability are developed and tested within the service as well.
For ESA's Gaia satellite, launched in 2013, astronomers of the ROB are involved in the preparation of the data processing and in the actual data reduction. Therefore, software development is done in a number of CUs (Coordination Units) that are part of the overall consortium DPAC (Data Processing and Analysis Consortium), which brings together more than 400 scientists. The specific contributions of the ROB are: the astrometric reduction of objects in the solar system, the determination of radial velocities based on the observed spectra, the characterisation of variable objects and the determination of stellar parameters of unusual objects.
Almost all of these projects are carried out in national or international context. The service is directly
involved in the operation of the Echelle spectrograph HERMES of the Mercator Telescope on La Palma (Spain). The data processing of astronomical satellites such as CoRoT, Kepler, Herschel, Gaia,… is done in close collaboration with national and international research groups.
Astronomers of the service develop and maintain computer applications (e.g. for radiation transport and hydrodynamics) or databases (e.g. with spectra or lists of spectral lines), both for their own research and to serve other scientists.
Members of the ssAA are involved in the digitisation activities at the ROB. A 2D-digitiser facility of high geometric and radiometric resolution and precision DAMIAN (Digital Access to Metric Images Archives Network) was built at ROB and has been operated under the DI/07 project financed by the Belgian Science Policy for digitising the astro-photographic archives of the ROB and other collections of federal institutes. The software and hardware development is continued at ROB for further improving the quality of the output. Minor digitisation projects of the ROB archives are going as well.
The activities related to the scientific information services within the ssAA consist of several tasks: answering questions and inquiries from public and press, assisting in all kind of outreach activities, giving general information on the ROB and on astronomy and astronomy related subjects, organize the visits to the ROB, including the organization and coordination of open doors days and related activities, all kind of assistance for exhibitions and public relations activities (press communications, press conferences etc.), managing of the archives and preparing of texts for printing or for the general web site.