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Geophysics and Astronomy

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As a part of reorganizations within the University the Department of Astronomy was merged with the Department of Physics on January 1, 2010, and a new Division of Geophysics and Astronomy was established within the Department. In addition to the astronomers the staff of the Division consists of geophysics and space physics personnel of the Department of Physics.

The research groups of the Division study the interstellar medium and star formation, stellar astrophysics, planetary system, space physics, solid Earth and the hydrosphere. While at the first sight geophysics and astronomy look quite different, there are natural connections between them, e.g., within solar-terrestrial physics and planetary geophysics.

Astronomy and space physics

In astronomy the telescopes of the European Southern Observatory (ESO) in Chile, the space-borne observing facilities of the European Space Agency (ESA) and the Nordic Optical Telescope in La Palma are our key sources of observational data. The ESO-related research is conducted in close co-operation with the Finnish Center for Astronomy with ESO (FINCA), established from 1.1.2010 in Turku. During the second half of 2010 three of our astronomers were employed through FINCA. The recent flagships of ESA, Herschel and Planck are in intensive use. For example, we use Planck data to locate future star forming regions within the Milky Way and coordinate a Herschel key program devoted to further studies of these sources. In stellar astrophysics one of our leading research line deals with the Sun and sun-like stars and their magnetic activity. In this field we also perform massive magnetohydrodynamic simulations using the supercomputers of the CSC – IT Centre for Science in Finland.

Solar activity is the driver of the solar wind and its perturbations, which are the focus of our research in space physics. We study solar plasma ejections, the associated shock structures, solar particle acceleration and their consequences in the near-Earth space in close co-operation with space physics research at the Finnish Meteorological Institute. Also in this field we use extensively data from several ESA and NASA spacecraft.

In planetary system research we study light scattering by small particles in the solar system as well as asteroid orbital and spin-shape inversion using MCMC methods. A highlight in this field was the international conference Electromagnetic and Light Scattering XII, with about 80 participants that we organized in June 28 - July 2, 2010. Furthermore we participate in the analysis of planetary plasma environments, in particular of Mars and Venus, using data from the ESA Mars Express and Venus Express observations. As one of the leading Finnish units providing scientific satellite instruments we presently work intensively with a solar X-ray and particle instrument onboard ESA’s Mercury mission to be launched in 2014. The instrument can be used independently in studies of solar eruptions, whereas its main task is to provide background in-formation to a UK-led X-ray instrument to determine the elemental composition of the surface of Mercury.

An important new opening was our success in the second Space Call of the EU’s 7th Framework Programme. Two international projects coordinated by our scientists started in December 2010. In the E-SQUID project, an improved SQUID-based readout system suitable for large X-ray to Infrared detector arrays used in space research is being developed. SEPServer project an integrated web-based interface to a comprehensive set of solar energetic particle data, related data on electromagnetic solar emissions and tools on analyzsing these data will be established. Furthermore, we participate in one more project to produce forecasting methods for space weather in a consortium led by the British Antarctic Survey.

Geophysics

In Solid Earth Geophysics laboratory the key subjects are the petrophysical and magnetic properties of meteorite impact craters and meteorites. The methods include field work and laboratory analysis e.g. density, porosity, magnetic susceptibility and remanence coupled with rock magnetic and paleomagnetic investigations of the rock samples. The highlight of this research in 2010 was proving the impact origin for the Keurusselkä impact structure. Also the various meteorite types were found among Almahata Sitta meteorites (recovered in the Nubian desert of Sudan) revealing diverse composition of its parent asteroid 2008 TC3, which may represent brecciated body resulting from collision of larger bodies of various types.

Hydrospheric research goes into cryosphere science, hydrology and oceanography. The main field is cryosphere. In sea ice dynamics basic research is performed and field data are analysed mainly from the Baltic Sea and Sea of Okhotsk. The coastal zone of freezing seas is examined with applications to ecology and engineering. One student took part in CHINARE 2010 expedition in the Eastern Arctic Ocean. Ice-covered boreal lakes are examined in northern Europe with emphasis on the role of the ice season in the annual cycle of lake ecology. Snow research includes seasonal snow in Finland and the snow surface layer (10 m) in the Dronning Maud Land, where expeditions were performed in austral summers 2009/2010 and 2010/2011, based in the research station Aboa. Topics in our oceanographic research include circulation and mixing processes in the Arctic Sea, and the exchange processes between the Nordic Seas and the North Atlantic.

Kuva 7.

Herschel satellite image of a cold core in an interstellar cloud. The object was first located by the Planck satellite. The red area at the centre of the image is a cold clump, T~12K, with a mass of some 140 solar masses. New stars are being formed within the bright regions inside the core. [The core is in Cepheus, between a larger molecular cloud in the south and a very young group of massive stars towards the north. The radiation pressure from the massive stars appears to have triggered the formation of the protostars we are now detecting.] (Juvela et al. 2010)