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LOFAR - Solar Key Science Project

LOFAR KSP "Solar Physics and Space Weather with LOFAR"

 

Workshops

8th Workshop

 

Objectives of the Key Science Project

The KSP "Solar Physics and Space Weather with LOFAR" is a European LOFAR activity. The KSP aims at using LOFAR for Solar and Space Weather studies. This includes the definition of solar observing modes, the development of the necessary software infrastructure, and making the observations available to the scientific community.

Definition of solar observation modes

The following solar observation modes are currently being developed:

    Routine imaging

    For studies of the long-term evolution of solar active regions, images of the radio Sun will be taken with a cadence of 1/min. This is chosen to be in coincidence with the Global H alpha Network.
    The Sun will be observed at about 20 frequencies simultaneously, covering the whole LOFAR frequency range. Since the solar radio radiation is due to plasma emission, these frequencies correspond to different heights in the solar corona. The exact number of frequencies is limited by the I/O capabilities of LOFAR's correlator. Each receiver at a LOFAR station can either process the signals from a low- or high-band antenna, but the station receivers can be split. This enables concurrent observations in LOFAR's low and high band. The loss of sensitivity and deterioration of station beams are not critical for solar observations, since the Sun is the strongest radio source in the sky.

Solar burst mode

During solar bursts, a higher image cadence of e.g. 0.1 s is necessary in order to cover the dynamics of the burst. The number of observed frequencies can be traded for image cadence if the I/O capabilities of LOFAR's correlator are exceeded.
The switching between routine imaging and the solar burst mode can be triggered by an external instrument ("burst bell"). This can be a remote LOFAR station operated in a stand-alone mode, or a solar spectrometer that preferably covers higher frequencies, e.g. up to 800 MHz, that correspond to lower heights in the solar corona. Thus, a burst can be detected before it reaches LOFAR's frequency range.

Joint observation campaigns

Joint observation campaigns of LOFAR with other ground- and space-based instruments (e.g. GREGOR, ALMA, RHESSI, STEREO, Hinode, or SDO) that observe the Sun in radio, optical, EUV, and X-ray wavelengths, enable dedicated studies of certain aspects of the solar activity, e.g. solar flares.

Single stations as spectrometers

The solar observing modes listed above are all based on solar imaging. However, a single station can also serve as a spectrometer by recording the intensity of the solar radio radiation over time in all available frequency channels. By combining several stations, the whole LOFAR frequency range can be covered.

Software development for solar observation modes

Adding solar observation modes to the LOFAR system requires the development and implementation of software packages specifically designed for this task. These efforts are integrated in the LOFAR Astronomical Development (LAD) project, that coordinates the overall software development for LOFAR, thus making it available as an astronomical instrument.

Solar Science Data Center

The tasks of a Solar Science Data Center are on the one hand the planning of observations in the different modes, and on the other hand archiving the data and making them available to the scientific community, as indicated in the small chart below.

Management structure of the KSP

The management structure of the Solar and Space Weather KSP can be found here: (PDF, 100kB)

 

LOFAR data of the Sun can be obtained via the LOFAR Solar Science Data Center.