Parallax data from the Hipparcos mission allow the direct distance to open clusters to be compared with the distance inferred from main sequence (MS) fitting. There are surprising differences between the two distance measurements, which indicate either the need for changes in the cluster compositions or reddening, underlying problems with the technique of main sequence fitting, or systematic er...

The tension between the Hipparcos parallax of the Pleiades and other independent distance estimates continues even after the new reduction of the Hipparcos astrometric data and the development of a new geometric distance measurement for the cluster. A short Pleiades distance from the Hipparcos parallax predicts a number of stars in the solar neighborhood that are sub-luminous at a given photosp...

We have obtained intermediate resolution spectra of eleven candidate brown dwarf members of the Pleiades open cluster using the Keck II telescope and LRIS spectrograph. Our primary goal was to determine the location of the “lithium depletion edge” in the Pleiades and hence to derive a precise age for the cluster. All but one of our 11 program objects have radial velocities appropriate for Pleia...

Because of its proximity and its youth, the Pleiades open cluster of stars has been extensively studied and serves as a cornerstone for our understanding of the physical properties of young stars. This role is called into question by the "Pleiades distance controversy," wherein the cluster distance of 120.2 ± 1.5 parsecs (pc) as measured by the optical space astrometry mission Hipparcos is sign...

The study of detached eclipsing binaries is one of the most powerful ways to investigate the properties of individual stars and stellar systems. We present preliminary masses, radii and effective temperatures for the eclipsing binary WWAurigae, which is composed of two metallic-lined A-type stars. We also reanalyse the data on HD23642, an A-type eclipsing binary member of the Pleiades open clus...

Today, many building software tools for evaluating energy efficiency are available. More than three hundred are listed by the US Department of Energy. Despite the diversity of the tools and their users, they generally share the same goals: to reduce the consumption of energy and even to produce surplus energy. We were interested in comparing the information provided by five softwares programmes...

We present new v sin i measurements for 235 lowmass stars in the Pleiades. The differential rotational broadening has been resolved for all the stars in our sample. These results, combined with previously published measurements, provide a complete and unbiased rotation data set for stars in the mass range from 0.6 to 1.2M . Applying a numerical inversion technique on the v sin i distributions, ...

ASTRONOMY AND ASTROPHYSICS Pleiades low-mass binaries: do companions affect the evolution of protoplanetary disks? ,, Abstract. We have observed 144 G and K dwarf members of the Pleiades cluster to search for close multiple systems using CFHT's Adaptive Optics adaptor in the near-IR. We detected 22 binary systems and 3 triples, with a separation between 0.08 and 6.9 arcsec (11–910 AU). After co...

The use of LAN-based clusters of computers for computational purposes has been in use for several years with significant success and acceptability. The introduction of the Internet infrastructure as the interconnection medium of the cluster allows for additional flexibility and transparency of such systems. PLEIADES is an Internet-based parallel/distributed system whose purpose is to allow user...