The Space Science Department of the Rutherford Appleton Laboratory has one of the most active solar physics research groups in the United Kingdom. Much of our work is done in collaboration with others in the UK and abroad. The recent highlight has been the outstanding picture of the Sun provided by our CDS instrument on the ESA/NASA SOHOmission
The programme is based mainly on the analysis and interpretation of data from a number of current and recent spacecraft instruments, principally those with which we had a hardware involvement - notably:
| SOHO/CDS | CDS - Coronal Diagnostic Spectrometer experiment on the forthcoming (1995) ESA SOHO mission. |
| Yohkoh | BCS - Bragg Crystal Spectrometer on Yohkoh Yohkoh(now in its eighth year of operation). |
| Spacelab II | CHASE - Coronal Helium Abundance Spacelab Experiment on Spacelab II. |
| SMM | XRP - X-Ray Polychromator on the US Solar Maximum Mission . |
| Coronas - F | The Resik instrument on the upcoming Russian Coronas -F spacecraft |
| Groundbased | Cambridge Interplanetary Scintillation - IPS radio telescope and hardware for quiet sun and eclipse observations on the JCMT - James Clerk Maxwell Telescope in Hawaii. |
CMEs are studied using CDS, SMM and ground based data to provide morphology and the sequence of events associated with CMEs. Modelling of the CME source region is undertaken, as well as identification and analysis of such events in interplanetary space. A prediction index is being investigated.
Our interest is mainly in diagnosing hot active regions and flare plasmas using line intensities, finding temperatures, densities, plasma flows and element abundances. Most recently we have measured the ratio of the photospheric to flare iron abundance for 27 flares with iron K beta line emission observed by the Yohkoh BCS. The same instrument was used in our study of the hottest part (electron temperature about 40MK) of soft x-ray flares.
Very impulsive flares and long duration events have also been investigated in addition to studies of specific single flares. SMM and other data (P78 and Hinotori) are being used to investigate abundances (including the use of Fe K alpha), high density diagnostics (Fe XXI 2-4 transitions) and active region temperature diagnostics (Mg XI and Si XIII).
CHASE provided data for determining coronal helium abundance as well as for studies of solar differential emission measure. The solar granulation, prominences and chromospheric profiles observed at 1 mm using the JCMT allow studies of the coolest plasmas in the solar atmosphere. Coronal structures and their evolution are investigated. A turbulent acceleration model of solar wind energisation is being developed.
The solar interior is studied theoretically, with investigations of the radiation transport from the core to the atmosphere, noting that a better understanding of photon scattering may solve the solar neutrino problem.
Many of the spectral lines observed from the sun are also seen in laboratory plasmas such as tokamaks. Consequently, the atomic data common to both can be investigated. Most recently, helium-like Ar XVII spectra from SMM and Alcator have been compared. Atomic data preparation and integral inversion work are being undertaken for the forthcoming SOHO CDS experiment. Our exploitation of CDS data will allow further investigation of many of the topics already studied.
The origin of the UV continuum in flare star IUE spectra is considered in terms of the the similar continuum in solar flare spectra. We are investigating flare and subflare spectra on YY Geminorum. Comparisons with ROSAT data will be made in collaboration.
Page maintained by M.Grande@rl.ac.uk .