We present the results of an investigation of the magnetic Ap star HD 965 with high spectral and time resolution. We determine exact radial velocities using spectra obtained with the UVES spectrograph on the ESO VLT. Special attention is given to the spectral lines of the Rare Earth Elements which in roAp stars exhibit the strongest radial velocity variations with pulsation period. Careful time series analysis did not detect any convincing evidence of pulsation in HD 965 with an upper limit in amplitude of $15-20\,{\rm m\,s}^{-1}$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Very high-quality, high-resolution optical CCD and photographic spectra of Vega reveal interstellar components in many spectra lines. The presence of these interstellar features suggests that detailed studies of such bright stars carried out with superb new data now available must take careful account of such contaminants in both abundance determinations and line profile fitting. Analyses of the interstellar features themselves can contribute to the general knowledge of the local ISM, an area previously largely limited to UV observations obtained by space facilties.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Asteroseismology may help detect diffusion-induced helium gradients inside Main-Sequence A stars. Models have been computed for 1.6 and 2.0 $M_{\odot}$ stars with pure helium diffusion, at different ages, so that the helium gradient lies at different depths inside the star. The adiabatic oscillation frequencies have been analysed and compared with those of a model without diffusion. Clear signatures of the diffusion-induced helium gradient are found in the so-called “second differences”. These frequency differences present modulations due to the partial reflection of the sound waves in the layer where the helium gradient occurs. A tentative application to the roAp star HD 60435 is presented.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the first results from our next-generation microlensing survey, the SuperMACHO project. We are using the CTIO 4m Blanco telescope and the MOSAIC imager to carry out a search for microlensing toward the Large Magellanic Cloud (LMC). We plan to ascertain the nature of the population responsible for the excess microlensing rate seen by the MACHO project. Our observing strategy is optimized to measure the differential microlensing rate across the face of the LMC. We find this derivative to be relatively insensitive to the details of the LMC's internal structure but a strong discriminant between Galactic halo and LMC self lensing. In December 2003 we completed our third year of survey operations. 2003 also marked the first year of real-time microlensing alerts and photometric and spectroscopic followup. We have extracted several dozen microlensing candidates, and we present some preliminary light curves and related information. Similar to the MACHO project, we find SNe behind the LMC to be a significant contaminant - this background has not been completely removed from our current single-color candidate sample. Our follow-up strategy is optimized to discriminate between SNe and true microlensing.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report on the detection of secondary spectra in five spectroscopic binary systems: HD 434, HD 861, HD 108642, HD 178449, and HD 216608. High signal-to-noise high resolution spectroscopic observations were carried out at the Bulgarian NAO Rozhen as part of an extended project concerned mainly with Am stars in binary systems. Our knowledge about early type binaries has serious gaps. This is true especially when it is only based on older photographic techniques. We concluded that photographic data involving longer orbital periods (where Doppler shifts due to the orbital motion are comparable or even less than the rotational broadening of the spectral lines) and early type stars (that have only a few and usually broad lines) should be revisited or at least used with caution. We demonstrate that for the five systems how CCD observations made with 2-m class telescopes can discover the binary nature or secondary spectra of many currently unresolved SB1 systems. Important astrophysical information such as the atmospheric parameters and the mass ratios are used to unravel previous misinterpretations of the data leading often to spurious orbits.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In September 2002 the discovery of a super Li-rich F-dwarf (J 37) in NGC 6633, an iron poor analogue of the better studied Hyades and Praecepe open clusters, was announced. This unique star was thought to be the smoking gun for the action of diffusion, models of which predict a narrow “Li-peak” at approximately the correct temperature. However, with more detailed studies into J 37's abundance pattern this star provides firm evidence for the accretion of planetesimals or other material from the circumstellar environment of new born stars.

Thanks to the specific predictions made about the behaviour of Be abundances, (the most striking of which being no Be in super-Li-rich dwarfs subject to diffusion) the opposing diffusion/accretion predictions can be tested.

Initial modelling of the Be line indicates that J 37 is as Be rich as it is Li rich; $\log N({\rm Be}) = 2.25 \pm 0.25$, and so is broadly consistent with an accretion-fuelled enhancement. However, that both Li and Be are enhanced by much more than the iron-peak elements (as determined in previous studies) suggests that diffusion also plays a role in increasing the abundances of Li and Be specifically.

Furthermore, a new data set from the UVES/UT2 combination has allowed the elemental abundance of iron to be measured. The preliminary stellar parameters are; $T_{\rm eff} \sim 7340\,{\rm K},\log g \sim 4.1$, microturbulence $\sim 4.3 {\rm km s^{-1}}, [{\rm Fe}/{\rm H}] \sim 0.50$. This again provides distinct evidence for the effects of accretion in J 37 and requires a new synthesis of the Be doublet.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using high-dispersion spectral observations of HD 101065 (Przybylski's star) we have identified the lines of heavy radioactive elements with atomic numbers from 84 to 99 in the spectrum of the star. We found the lines of all these elements except At (Z=85) and Fr (Z=87). We try to explain a presence of such heavy species in the atmosphere of this star as a result of radioactive decay of Th and U nuclei and neutron capture process producing some transuranium isotopes. The necessary conditions for these processes to work may appear due to atomic diffusion and favorable accumulation of the thorium and uranium nuclei in the upper of the PS atmosphere.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Galaxy-galaxy lensing (GGL) measures the 2-point cross-correlation between galaxies and mass in the universe. In this work we seek to generalise this effect by considering the third-order correlations between galaxies and mass: galaxy-galaxy-galaxy lensing. We introduce the higher-order cross-correlation functions and discuss their physical interpretation in terms of the halo model. We then demonstrate that measuring the lensing shear of background galaxies about foreground galaxy pairs, which we term galaxy-galaxy-galaxy lensing, provides a measure of the third-order cross functions. We note that current surveys in which detections of the cosmic shear 3-point correlation function have been reported should also be able to detect galaxy-galaxy-galaxy lensing. Indeed, we suggest that this effect may already have been detected in recent studies of GGL.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Several recent papers have studied lensing of the CMB by large-scale structures, which probes the projected matter distribution from $z=10^3$ to $z\simeq 0$. This interest is motivated in part by upcoming high resolution, high sensitivity CMB experiments, such as APEX/SZ, ACT, SPT or Planck, which should be sensitive to lensing. In this paper we examine the reconstruction of the large-scale dark matter distribution from lensed CMB temperature anisotropies. We go beyond previous work in using numerical simulations to include higher order, non-Gaussian effects and find that the convergence and its power spectrum are biased, with the bias increasing with the angular resolution. We also study the contamination by the kinetic Sunyaev-Zel'dovich signal, which is spectrally indistinguishable from lensed CMB anisotropies, and find that it leads to an overestimate of the convergence. We finish by estimating the sensitivity of the previously cited experiments and find that all of them could detect the lensing effect, but would be biased at around the 10% level.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

BAGNULO: I would like to ask Mathys and Moss to comment about the possible detection of the radial gradients of the magnetic .elds in Ap stars. What would be the consequence of such a feature on the stellar atmosphere? I refer in particular to that the length scale for horizontal variability of the field is not less than 105 km, whereas the depth of the photosphere may be 100 times less.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We calculate multicomponent radiatively driven stellar wind models suitable for A stars. We discuss the possible decoupling of individual elements from the stellar wind and its influence on the chemical peculiarity of these stars. We obtain a range of stellar parameters for different types of multicomponent flow.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Cosmic shear surveys are now collecting photometric redshifts of the sources. We analyse how such photometric redshifts can be used to perform a genuine 3D analysis of the shear fields, with enhanced statistical power over conventional shear analysis on the sky. In particular, 3D lensing has the potential to measure accurately the equation of state of Dark Energy, with a possibility of measuring $w$ with an accuracy of a few percent. Like the microwave background, 3D lensing observables are calculable ab initio, and are largely unaffected by complex astrophysical processes which may limit their power. In this context, we review how 3D information from photometric redshifts can reduce a possible physical systematic effect, arising from intrinsic alignments of galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We study the dark matter halos of galaxies with galaxy-galaxy lensing using the COMBO-17 survey. This survey offers an unprecedented data set for studying lens galaxies at $z=0.2-0.7$ including redshift information and spectral classification from 17 optical filters for objects brighter than $R=24$. So far, redshifts and classification for the lens galaxies have mainly been available for local surveys like the Sloan Digital Sky Survey (SDSS). Further, redshifts for the source galaxies have typically not been available at all but had to be estimated from redshift probability distribution which – for faint surveys – even had to be extrapolated.

To study the dark matter halos we parametrize the lens galaxies as singular isothermal spheres (SIS) or by Navarro-Frenk-White (NFW) profiles. In both cases we find a dependence of the velocity dispersion or virial radius, respectively, on lens luminosity and colour. For the SIS model, we are able to reproduce the Tully-Fisher/Faber-Jackson relation on a scale of $150h^{-1}~\mathrm{kpc}$. For the NFW profile we also calculate virial masses, mass-to-light ratios and rotation velocities.

Finally, we investigate differences between the three survey fields used here.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Observations of multiple-image gravitational lens systems suggest that the projected mass distributions of galaxy haloes may contain substantial inhomogeneities. The fraction of the halo mass in dense substructure is still highly uncertain, but could be as large as a few percent. While halo substructure is seen in numerical simulations of CDM haloes, little of this substructure survives in the innermost regions of haloes, and thus the observational claims for substructure at small projected radii are slightly surprising. There is evidence, however, that even the highest-resolution simulations published to-date are still limited by numerical effects that heat and disrupt substructure artificially in high-density regions. By comparing numerical and semi-analytic (SA) models of halo substructure, we show that current simulations probably underestimate the mass fraction in substructure at small projected radii, by a factor of at least 2–3. We discuss the prospects for using lensing observations as a fundamental test of the nature of dark matter.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Under the currently popular CDM model, mass plays the major role in evolution of large scale structure of the universe. In order to examine the paradigm based on observations, it would be ideal to use purely mass selected object catalog. Weak lensing surveys enable a blind search of cluster scale objects, and thus could provide such catalogs. We are working on a weak lensing survey using Subaru Prime Focus Camera (Suprime-Cam). In this note, we introduce our survey strategy, and the status as well as the performance of Suprime-Cam as a weak lensing surveyor.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

COWLEY: For O. Kochukov: This concerns the λ5200 feature which you could reproduce in the cooler Ap stars, but not in the hotter ones: 1) Do you know which atoms or ions cause the depression in the cooler stars?

2) In the hotter stars, can you suggest a cause for the observed depressions in these objects? To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this study we use preliminary atmospheric parameters for the A0 Ib supergiant $\eta$ Leo ($T_{\rm eff}, \log g$ and microturbulent velocity) to provide initial estimates of the elemental abundances from S II, Ti II, Cr II, Fe I and Fe II lines by using spectrograms with a two pixel resolution of 0.072 Å and signal-to-noise ratio $\ge$ 200 taken at the Dominion Astrophysical Observatory.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We consider a contribution of microlensing to the X-ray variability of high-redshifted QSOs. Cosmologically distributed gravitational microlenses could be localized in galaxies (or even in bulge or halo of gravitational macrolenses) or could be distributed in a uniform way. We have analyzed both cases of such distributions. We found that the optical depth for gravitational microlensing caused by cosmologically distributed deflectors could be significant and could reach $10^{-2} - 0.1$ at $z\sim 2$. This means that cosmologically distributed deflectors may contribute significantlly to the X-ray variability of high-redshifted QSOs ($z>2$). Considering that the upper limit of the optical depth ($\tau\sim 0.1$) corresponds to the case where dark matter forms cosmologically distributed deflectors, observations of the X-ray variations of unlensed QSOs can be used for the estimation of the dark matter fraction of microlenses.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have started an analysis of the sharp-lined superficially normal A3IVp star 95 Leo. We are using $2.4 \AA \mathrm {mm}^{-1}$ spectrograms covering $\lambda\lambda 3830-4934$ obtained with the 1.22-m telescope of the Dominion Astrophysical Observatory using CCD detectors. Their mean signal-to-noise ratios are $\ge\,200$. The spectrograms are rectified and measured with the interactive computer graphics program REDUCE of Graham Hill and his associates. In measuring the spectrum with the VLINE routine, we use the fixed parameter feature to deconvolute metallic line blends and to measure weak lines. Effective temperature and surface gravity estimates based on spectrophotometry and H$\gamma$ profile fitting were given in the literature as 8300 K and 3.65, respectively.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The stellar winds of A supergiants can have a significant influence on their emergent spectra. Here we present the hydrogen line profiles of a model based on the stellar parameters of HD 12953. The radiative transfer equation is solved in two dimensions in axial symmetry. We do not include the velocity field by the Sobolev approximation, but in detail using the Lorentz transformation. This allows us to correctly include the stellar wind, since the velocity gradients in A supergiants are too small for the Sobolev approximation to be valid.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html