D S Bloomfield

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A new application of wavelet analysis is presented that utilizes the inherent phase information residing within the complex Morlet transform. The technique is applied to a weak solar magnetic network region, and the temporal variation of phase difference between TRACE 1700 8 and SOHO/SUMER C ii 1037 8 intensities is shown. We present, for the first time in(More)
Spectropolarimetric time series data of the primary spot of active region NOAA 9448 were obtained in the Si i 10827 Å line and the He i 10830 Å multiplet with the Tenerife Infrared Polarimeter. Throughout the time series the spectrograph slit was fixed over a region covering umbra, a light bridge, penumbra, and quiet sun. We present speeds of running(More)
Oscillations in network bright points (NBPs) are studied at a variety of chromospheric heights. In particular, the three-dimensional variation of NBP oscillations is studied using image segmentation and crosscorrelation analysis between images taken in light of Ca iiK3, H core, Mg i b2, andMg i b1 0:4 Å. Wavelet analysis is used to isolate wave packets in(More)
Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler Interferometer on the Solar Heliospheric Observatory to study wave behaviour in differing magnetic environments. Wavelet(More)
A detailed study is presented of the decaying solar active region NOAA 10103 observed with the Coronal Diagnostic Spectrometer (CDS), the Michelson Doppler Imager (MDI) and the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO). Electron density maps formed using Si x(356.03 Å/347.41 Å) show that the density(More)
Recent calculations of atomic data for Fe XV have been used to generate theoretical line ratios involving n = 3–4 transitions in the soft X-ray spectral region (∼52–83 Å), for a wide range of electron temperatures and densities applicable to solar and stellar coronal plasmas. A comparison of these with solar flare observations from a rocket-borne(More)
We present far-UV and UV spectroscopic observations of Proxima Centauri obtained as part of our continued investigation into the optically thin approximation assumed for the transition regions of late-type stars. Significant opacity is found in the C iii lines during both the quiescent and flaring states of Proxima Cen, with up to 70% of the expected flux(More)
In this paper we investigate the validity of the optically thin assumption in the transition region of the late–type star AU Mic. We use Far–Ultraviolet Spectroscopic Explorer (FUSE) observations of the C  multiplet and O  resonance lines, hence yielding information at two different levels within the atmosphere. Significant deviations from the(More)