We present an analysis of the effects of environment on the photometric properties of galaxies in the core of the Shapley supercluster at z= 0.05, one of the most massive structures in the local universe. The Shapley Optical Survey (SOS) comprises archive Wide Field Imager (WFI) optical imaging of a 2.0 deg2 region containing the rich clusters A3556, A3558 and A3562 which demonstrate a highly complex dynamical situation including ongoing cluster mergers. The B−R/R colour–magnitude relation has an intrinsic dispersion of 0.045 mag and is 0.015 ± 0.005 mag redder in the highest‐density regions, indicative of the red sequence galaxy population being 500‐Myr older in the cluster cores than towards the virial radius. The B−R colours of galaxies are dependent on their environment, whereas their luminosities are independent of the local density, except for the very brightest galaxies (MR < −22). The global colours of faint (≳M*+ 2) galaxies change from the cluster cores where ∼90 per cent of galaxies lie along the cluster red sequence to the virial radius, where the fraction has dropped to just ∼20 per cent. This suggests that processes directly related to the supercluster environment are responsible for transforming faint galaxies, rather than galaxy merging, which should be infrequent in any of the regions studied here. The largest concentrations of faint blue galaxies are found between the clusters, coincident with regions containing high fractions of ∼L* galaxies with radio emission indicating starbursts. Their location suggests star formation triggered by cluster mergers, in particular the merger of A3562 and the poor cluster SC 1329‐313, although they may also represent recent arrivals in the supercluster core complex. The effect of the A3562–SC 1329‐313 merger is also apparent as a displacement in the spatial distribution of the faint galaxy population from both the centres of X‐ray emission and the brightest cluster galaxies for both systems. The cores of each of the clusters/groups are marked by regions that have the lowest blue galaxy fractions and reddest mean galaxy colours over the whole supercluster region, confirming that star formation rates are lowest in the cluster cores. In the cases of A3562 and SC 1329‐313, these regions coincide with the centres of X‐ray emission rather than the peaks in the local surface density, indicating that ram‐pressure stripping may have an important role in terminating any remnant star formation in galaxies that encounter the dense intracluster medium (ICM) of the cluster cores.

We present the Shapley Optical Survey, a photometric study covering a ∼2-deg 2 region of the Shapley supercluster core at z ∼ 0.05 in two bands (B and R). The galaxy sample is complete to B = 22.5 (>M * + 6, N gal = 16 588) and R = 22.0 (>M * + 7, N gal = 28 008). The galaxy luminosity function (LF) cannot be described by a single Schechter function due to dips apparent at B ∼ 17.5 (M B ∼ −19.3) and R ∼ 17.0 (M R ∼ −19.8) and the clear upturn in the counts for galaxies fainter than B and R ∼ 18 mag. We find, instead, that the sum of a Gaussian and a Schechter function, for bright and faint galaxies, respectively, is a suitable representation of the data. We study the effects of the environment on the photometric properties of galaxies, deriving the galaxy LFs in three regions selected according to the local galaxy density, and find a marked luminosity segregation, in the sense that the LF faint end is different at more than 3σ confidence level in regions with different densities. In addition, the LFs of red and blue galaxy populations show very different behaviours: while red sequence counts are very similar to those obtained for the global galaxy population, the blue galaxy LFs are well described by a single Schechter function and do not vary with the density. Such large environmentally dependent deviations from a single Schechter function are difficult to produce solely within galaxy merging or suffocation scenarios. Instead the data support the idea that mechanisms related to the cluster environment, such as galaxy harassment or ram-pressure stripping, shape the galaxy LFs by terminating star formation and producing mass-loss in galaxies at ∼M * + 2, a magnitude range where blue late-type spirals used to dominate cluster populations, but are now absent.

The first 2‐D distributions of the polarization angle and of the relative color index for the K‐corona of 29 March 2006 are presented. The distributions illustrate the efficiency of the total solar eclipse approach for high‐precision measurements of the K‐corona continuum in the range < 1.4 R⊙. Natural ground and space total solar eclipses caused by external occulting the bright solar‐disk light by the Moon or Earth group planets are discussed. Calculations of the eclipse magnitude m are carried out to show ideal conditions for total solar eclipse observations in space from Lagrange point L2 for Mars (m ≈ 1.025). The illumination in Mars' shadow is estimated to equal 5.6 × 10−11 for the wavelength of 550 nm. No internal or external occulting coronagraphs are needed. Partial solar eclipses with m > 0.91 can be observed from Lagrange points L2 for Mercury, Venus, and Earth.

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They reveal the absence of identity in energy distributions in the continua of the K-corona and photosphere. The quasi-symmetry of RCI distributions relative to the projection of the heliospheric current sheet in "the sky plane" excludes the contribution of the dust component. Reddening with distance over the entire corona at all positional angles is the first observational confirmation of theoretical calculations by Reginald et al. [8]. Therefore, the RCI can be considered as an indicator of the expansion of the corona. Different coronal structures have different RCI values. The existence of diffuse and structural components, correlation with the coronal structure, and bluing in the range <1.2-1.3 R  are noted.