LOFAR Interplanetary Scintillation (IPS) and Faraday Rotation (FR) Inner-Heliosphere Case Studies
M.M. Bisi
RAL Space, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, OX11 0QX, England, UK
R.A. Fallows (2), C. Sobey (2), T. Eftekhari (2,3), E.A. Jensen (4), B.V. Jackson (5), H.-S. Yu (5), M. Tokumaru (6), and Dusan Odstrcil (7,8)
We present the latest results on the progress made using the LOw Frequency ARray (LOFAR) next-generation radio telescope for inner-heliosphere space-weather case studies. We primarily use the two radio-observing techniques of interplanetary scintillation (IPS) and of heliospheric Faraday rotation (FR). IPS has been used for over half a century for heliospheric science, and FR is typically an astrophysical technique that uses pulsars and extragalactic sources to study the Galactic magnetic field, but here we apply it for investigating the inner heliosphere. We also use three-dimensional modelling and reconstructions using other data as input (such as additional observations of IPS from the Solar Terrestrial Environment Laboratory – STEL/STELab IPS arrays) to support and better-interpret the LOFAR results along with in-situ data and ambient magnetic fields. The determination of heliospheric FR, combined with observations of IPS, can provide essential information on the Sun’s extended “evolving” magnetic-field structure out into the inner heliosphere. LOFAR is an interferometric phased-array radio telescope that can be used to observe between ~10 MHz (depending on ionospheric conditions) and ~240 MHz, and consists of many relatively low-cost antennas. These antennas are grouped into ‘stations’ that are located in an area of ~100 km diameter in The Netherlands, with additional larger single “international” stations outside of The Netherlands. LOFAR is a pathfinder to the Square Kilometre Array (SKA). Currently, there are eight LOFAR international stations spread across central and Western Europe (five in Germany, one in France, one in Sweden, and one in the UK) with several more in the planning and build stages (three in Poland, two in Germany, one wanted in Ireland, and possibly one in the UK).