We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using 2 the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0.49 ± 0.02 (66 ± 2 AU) and a mass of 68 ± 5 MJ based on ...

The discrepancy between the Pleiades cluster distance based on Hipparcos parallaxes and main sequence fitting is investigated on the basis of Strömgren photometry of F-type stars. Field stars with the same metallicity as the Pleiades have been selected from the m1 index and a technique has been developed to locate the ZAMS of these field stars in color-magnitude diagrams based on the color/temp...

We analyze the high-excitation O i l7774 triplet in high-resolution, moderate signal-to-noise ratio spectra of 15 Pleiades and eight M34 open cluster dwarfs over the effective temperature range of 5048–6172 K. Relative O abundances have been derived using model atmospheres interpolated from four different sets of ATLAS9 grids. In contrast to existing non-LTE (NLTE) predictions, a dramatic incre...

Two stellar-dynamical models of binary-rich embedded proto-Orion-Nebula-type clusters that evolve to Pleiades-like clusters are studied with an emphasis on comparing the stellar mass function with observational constraints. By the age of the Pleiades (about 100 Myr) both models show a similar degree of mass segregation which also agrees with observational constraints. This thus indicates that t...

We have performed a deep, wide-field imaging survey of the Pleiades cluster (Melotte 22) in the R and I-bands to search for very low-mass stars and brown dwarfs. The survey extends over ∼2.5 square degrees around the cluster’s center down to a ∼90% completeness limit of R∼23 and I∼22. We find 26 objects whose location in the (I, R-I) color–magnitude diagram is consistent with them being Pleiade...

This paper addresses uncertainty modelling of shorelines by comparing fuzzy sets and random sets. Both methods quantify extensional uncertainty of shorelines extracted from remote sensing images. Two datasets were tested: pan-sharpened Pleiades with four bands (Pleiades) and pan-sharpened Pleiades stacked with elevation data as the fifth band (Pleiades + DTM). Both fuzzy sets and random sets mo...