Search

The precision differential abundance (PDA) technique is applied to the mid-F stars Procyon and $\theta$ Scl using spectra from the ESO UVESPOP library. We relate PDA patterns to endogenous processes related to condensation or to exogenous processes connected to Galactic chemical evolution (GCE). We employ one-dimensional LTE models, but emphasize the use of weaker lines ($\leq$ 20 m\AA) than are typically used in such studies. We compare our results with PDAs of solar-type stars. Abundances and PDAs are determined for 28 elements: C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, and Gd. A plot of PDAs ($\theta$ Scl minus Procyon) vs. $Z$ shows a highly significant correlation. Moreover, local substructure of the plot for the elements Ca-Zn and neutron-addition elements is similar to that which can be found for solar twins. Our PDA vs. $Z$ plot structural similarity to plots that can be made from the extensive work of Bedell et al. (2018). That PDA structure and substructure is clearly a function of age., Comment: 8 pages, 4 figures. Accepted for publication in Astronomische Nachrichten

The sharp-line spectrum of the Bp star HR 6000 has peculiarities that distinguish it from those of the HgMn stars with which it is sometimes associated. The position of the star close to the center of the Lupus 3 molecular cloud, whose estimated age is on the order of 9.1 +/- 2.1 Myr, has lead to the hypothesis that the anomalous peculiarities of HR 6000 can be explained by the young age of the star. Observational material from HST provides the opportunity to extend the abundance analysis previously performed for the optical region and clarify the properties of this remarkable peculiar star. Our aim was to obtain the atmospheric abundances for all the elements observed in a broad region from 1250 to 10000 A. An LTE synthetic spectrum was compared with a high-resolution spectrum observed with STIS equipment in the 1250-3040 A interval. The adopted model is an ATLAS12 model already used for the abundance analysis of a high-resolution optical spectrum observed at ESO with UVES. The stellar parameters are Teff=13450K, logg=4.3, and zero microturbulent velocity. Abundances for 28 elements and 7 upper limits were derived from the ultraviolet spectrum. Adding results from previous work, we have now quantitative results for 37 elements, some of which show striking contrasts with those of a broad sample of HgMn stars. The analysis has pointed out ionization anomalies and line-to-line variation in the derived abundances, in particular for silicon. The inferred discrepancies could be explained by non-LTE effects and with the occurrence of diffusion and vertical abundance stratification. In the framework of the last hypothesis, we obtained, by means of trial and error, empirical step functions of abundance versus optical depth log(tau_5000) for carbon, silicon, manganese, and gold, while we failed to find such a function for phosphorous., Comment: Accepted by Astronomy & Astrophysics for publication

The NIST database lists several Mn II lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700 A interval. We aimed to assign energy levels and log gf values to these lines. Semi-empirical line data for Mn II computed by Kurucz were used to synthesize the ultraviolet spectrum of the slow-rotating, HgMn star HD 175640. The spectrum was compared with the high-resolution spectrum observed with the HST-STIS equipment. A UVES spectrum covering the 3050-10000 A region was also examined. We determined a total of 73 new energy levels, 58 from the STIS spectrum of HD 175640 and another 15 from the UVES spectrum. The new energy levels give rise to numerous new computed lines. We have identified more than 50% of the unclassified lines listed in the NIST database and have changed the assignement of another 24 lines. An abundance analysis of the star HD 175640, based on the comparison of observed and computed ultraviolet spectra in the 1250-3040 A interval, is the by-product of this study on Mn II., Comment: Paper accepted by Astronomy & Astrophysics

The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmospheric parameters of the central star are constrained employing non-LTE spectrum synthesis. Overall chemical abundances are close to solar. Column densities of the dominant ions of several elements, as well as excitation temperatures and the mean electron density are well accounted for by a simple model. Several features, including the degree of ionization, are less well described. HD 94509 is a Be star with a stable shell, close to the terminal-age main sequence. The dynamical state of the shell and the unusually shaped, but symmetric line profiles, require a separate study., Comment: 10 pages, 9 tables, 13 figures; accepted for publication by Astronomy and Astrophysics

Many abundance studies are based on spectrum synthesis and $\chi$-squared differences between the synthesized and an observed spectrum. Much of the spectra so compared depend only weakly on the elemental abundances. Logarithmic plots of line depths rather than relative flux make this more apparent. We present simulations that illustrate a simple method for finding regions of the spectrum most sensitive to abundance, and also some caveats for using such information. As expected, we find that weak features are the most sensitive. Equivalent widths of weak lines are ideal features, because of their sensitivity to abundances, and insensitivity to factors that broaden the line profiles. The wings of strong lines can also be useful, but it is essential that the broadening mechanisms be accurately known. The very weakest features, though sensitive to abundance, should be avoided or used with great caution because of uncertainty of continuum placement as well as numerical uncertainties associated with the subtraction of similar numbers., Comment: 6 pages, 10 figures, 3 tables, accepted for publication in MNRAS

We present a kinematic analysis of three triple stellar systems belonging to two open clusters: CPD-60{\deg}961 and HD66137 in NGC2516, and HD315031 in NGC6530. All three systems are hierarchical triples with a close binary bound to a third body in a wider orbit, whose presence is detected through velocity variations of the close binary barycentre. Orbital parameters are derived from radial velocity curves. Absolute parameters for all stars are estimated assuming cluster membership. Some dynamical and evolutionary aspects of these systems are discussed, particularly the possible influence of Kozai cycles. The two systems of NGC2516 have similar orbital configurations with inner periods of 11.23 d and 8.70 d and outer periods of 9.79 yr and 9.24 yr. We report also radial velocity measurements of the components of the visual binary CPD-60{\deg}944 in NGC2516. Including results from previous works, this cluster would harbor 5 hierarchical triples. The young system HD315031 has an inner binary with a period of 1.37 d and a very eccentric (e=0.85) outer orbit with a period of 483 d. Possible dynamical evolutionary scenarios are discussed. Long-term radial velocity monitoring is highlighted as strategy for the detection of subsystems with intermediate separations, which are hard to cover with normal spectroscopic studies or visual techniques., Comment: 9 pages, 5 figures. Accepted by Monthly Notices of the Royal Astronomical Society

The Herbig Ae star PDS2 (CD -53 251) is unusual in several ways. It has a high Galactic latitude, unrelated to any known star-forming region. It is at the cool end of the Herbig Ae sequence, where favorable circumstances facilitate the determination of stellar parameters and chemical abundances. We find $T_{\rm eff} = 6500$ K, and $\log(g) = 3.5$. The relatively low $v\cdot\sin(i) = 12\pm2$ \kms made it possible to use mostly weak lines for the abundances. PDS2 appears to belong to the class of Herbig Ae stars with normal volatile and depleted involatile elements. This pattern is seen not only in $\lambda$ Boo stars, but in some post AGB and RV Tauri stars. The appearance of the same abundance pattern in young stars and highly evolved giants strengthens the hypothesis of gas-grain separation for its origin. The intermediate volatile zinc can violate the pattern of depleted volatiles., Comment: Accepted MNRAS; Online material at http://dept.astro.lsa.umich.edu/~cowley/PDS2.html

We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. The magnetic field geometries of these stars, investigated with spectropolarimetric time series, can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields have recently been observed with X-shooter in the visible and the near-IR, as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of the accretion flow and the accretion disk gas emission., Comment: Six pages, three figures, to appear in the Proceedings of the Conference "Physics at the Magnetospheric Boundary"

Gas accreting onto a galaxy will be of low metallicity while halo gas due to a galactic fountain will be of near-solar metallicity. We test these predictions by measuring the metal absorption line properties of halo gas 5 kpc above the plane of the edge-on galaxy NGC 891, using observations taken with HST/STIS toward a bright background quasar. Metal absorption lines of Fe II, Mg II, and Mg I in the halo of NGC 891 are clearly seen, and when combined with recent deep H I observations, we are able to place constraints on the metallicity of the halo gas for the first time. The H I line width defines the line broadening, from which we model opacity effects in these metal lines, assuming the absorbing gas is continuously distributed in the halo. The gas-phase metallicities are [Fe/H] = -1.18 +/- 0.07 and [Mg/H] = -0.23 +0.36/-0.27 (statistical errors) and this difference is probably due to differential depletion onto grains. When corrected for such depletion using Galactic gas as a guide, both elements have approximately solar or even supersolar abundances. This suggests that the gas is from the galaxy disk, probably expelled into the halo by a galactic fountain, rather than from accretion of intergalactic gas, which would have a low metallicity. The abundances would be raised by significant amounts if the absorbing gas lies in a few clouds with thermal widths smaller than the rotational velocity of the halo. If this is the case, both the abundances and [Mg/Fe] would be supersolar., Comment: 24 pages, 4 figures

The recent availability of ESO's high-resolution spectrograph CRIRES offers now the opportunity to study numerous spectral features in the near-IR in intermediate-mass main-sequence and pre-main-sequence stars. High-resolution CRIRES spectra were obtained in three spectral regions, two regions around 1mu and one region around 1.57mu containing magnetically sensitive Fe I lines. The largest number of near-IR spectral features was detected and identified in the well-studied magnetic Ap star gamma Equ. Nearly 30% of the spectral lines in the Ap star HD154708, with one of the strongest magnetic fields known among the Ap stars of the order of 25kG, remain unidentified due to a lack of atomic data. Only very few lines belonging to the rare earth element group have been identified in both Ap stars. A number of spectral lines including the Ce III and Dy II lines appear magnetically split due to the presence of a strong magnetic field in their atmospheres. Variable behaviour of lines of the elements He, N, Mg, Si, and Fe over the rotation period in the spectra of HD101412 confirm our previous finding of variability in the optical region. Due to the very fast rotation of 51Oph, only a few spectral lines have been identified with certainty., Comment: 18 pages, 12 figures, 6 tables, accepted for publication in A&A

We describe and model emission lines in the first overtone band of CO in the magnetic Herbig Ae star HD 101412. High-resolution CRIRES spectra reveal unusually sharp features which suggest the emission is formed in a thin disk centered at 1 AU with a width 0.32 AU or less. A wider disk will not fit the observations. Previous observations have reached similar conclusions, but the crispness of the new material brings the emitting region into sharp focus., Comment: Accepted as Astronomy and Astrophysics Letter; 4 pages, 5 figures

Our knowledge of the presence and the role of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present the magnetic properties of four Herbig Ae/Be stars that have not been previously studied in detail. Our results for the three Herbig Ae/Be stars HD97048, HD150193, and HD176386 are based on multi-epoch low-resolution spectra obtained in spectropolarimetric mode with FORS2 mounted on the VLT. New high-resolution polarimetric spectra were obtained for MWC480 with the SOFIN spectrograph installed at the Nordic Optical Telescope. We discuss 41 FORS2 low-resolution observations of the Herbig Ae/Be stars HD97048, HD150193, and HD176386 and determine their rotational periods. Using stellar fundamental parameters and the longitudinal magnetic field phase curves, we place constraints on the magnetic field geometry. Three high-resolution circularly polarised SOFIN spectra obtained for MWC480 were measured using the moment technique where wavelength shifts between right- and left-hand side circularly polarised spectra are interpreted in terms of a longitudinal magnetic field . Our search for periodicities resulted in P=0.693d for HD97048, P=1.317d for HD150193, and P=0.899d for HD176386. The magnetic field geometry can likely be described by a centred dipole with a polar magnetic field strength B_d of several hundred Gauss. The longitudinal magnetic-field measurements of MWC480 reveal the presence of a strong kG field, which was undetected in our previous low-resolution polarimetric observations with FORS1. A weak magnetic field was detected in the circumstellar components of the Ca II H&K lines and the Na I D lines, indicating a complex interaction between the stellar magnetic field and the circumstellar environment., Comment: 8 pages, 9 figures, 5 tables, accepted for publication in A&A

We determine abundances from the absorption spectrum of the magnetic Herbig Ae star HD 190073 (V1295 Aql). The observations are primarily from HARPS spectra obtained at a single epoch. We accept arguments that the presence of numerous emission lines does not vitiate a classical abundance analysis, though it likely reduces the achievable accuracy. Most abundances are closely solar, but several elements show departures of a factor of two to three, as an earlier study has also shown. We present quantitative measurements of more than 60 emission lines, peak intensities, equivalent widths, and FWHM's. The latter range from over 200 km/s (H-alpha, He D3) down to 10--20 km/s (forbidden lines). Metallic emission lines have intermediate widths. We eschew modeling, and content ourselves with a presentation of the observations a successful model must explain. Low-excitation features such as the Na I D-lines and [O I] appear with He I D3, suggesting proximate regions with widely differing Te and Ne as found in the solar chromosphere. The [O I] and [Ca II] lines show sharp, violet-shifted features. Additionally, [Fe II] lines appear to be weakly present in emission., Comment: 7 pages, 10 figures. To appear in Astronomische Nachrichten, Proceedings of the 7th Potsdam Thinkshop on "Magnetic Fields in Stars and Exoplanets."

The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our understanding of the formation mechanisms of stars with Hg and Mn peculiarities themselves, but also for the general understanding of B-type star formation in binary systems. The origin of the abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. The connection between HgMn peculiarity and membership in binary and multiple systems is supported by our observations during the last decade. The important result achieved in our studies of a large sample of HgMn stars is the finding that most HgMn stars exhibit spectral variability of various chemical elements, proving that the presence of an inhomogeneous distribution on the surface of these stars is a rather common characteristic and not a rare phenomenon. Further, in the studied systems, we found that all components are chemically peculiar with different abundance patterns. Generally, He and Si variable Bp stars possess large-scale organised magnetic fields that in many cases appear to occur essentially in the form of a single large dipole located close to the centre of the star. The presence of magnetic fields in the atmospheres of HgMn stars has been demonstrated in several studies. In addition to the measurements of longitudinal and quadratic magnetic fields, this work also showed evidence for a relative magnetic intensification of Fe II lines produced by different magnetic desaturations induced by different Zeeman-split components., Comment: 10 pages, 9 figures, 1 table, to appear in Astronomische Nachrichten, Proceedings of the 7th Potsdam Thinkshop on "Magnetic Fields in Stars and Exoplanets"

We present a detailed analysis of the reliability of abundance and magnetic maps of Ap stars obtained by Zeeman Doppler mapping (ZDM). It is shown how they can be adversely affected by the assumption of a mean stellar atmosphere instead of appropriate "local" atmospheres corresponding to the actual abundances in a given region. The essenceof the difficulties was already shown by Chandrasekhar's picket-fence model. The results obtained with a suite of Stokes codes written in the Ada programming language and based on modern line-blanketed atmospheres are described in detail. We demonstrate that the high metallicity values claimed to have been found in chemically inhomogeneous Ap star atmospheres would lead to local temperature structures, continuum and line intensities, and line shapes that differ significantly from those predicted by a mean stellar atmosphere. Unfortunately, past applications of ZDM have consistently overlooked the intricate aspects of metallicity with their all-pervading effects. The erroneous assumption of a mean atmosphere for a spotted star can lead to phase-dependent errors of uncomfortably large proportions at varying wavelengths both in the Stokes I and V profiles, making precise mapping of abundances and magnetic field vectors largely impossible. The relation between core and wings of the H_beta line changes, too, with possible repercussions on the determination of gravity and effective temperature. Finally, a ZDM analysis of the synthetic Stokes spectra of a spotted star reveals the disturbing differences between the respective abundance maps based on a mean atmosphere on the one hand, and on appropriate "local" atmospheres on the other. We then discuss what this all means for published ZDMresults. Our discussion makes it clear that realistic local atmospheres must be used, especially if credible small-scale structures are to be obtained., Comment: Accepted for publication in MNRAS

Despite of the importance of magnetic fields for the full understanding of the properties of accreting Herbig Ae/Be stars, these fields have scarcely been studied over the rotation cycle until now. One reason for the paucity of such observations is the lack of knowledge of their rotation periods. The sharp-lined young Herbig Ae star HD101412 with a strong surface magnetic field became in the last years one of the most studied targets among the Herbig Ae/Be stars. A few months ago we obtained multi-epoch polarimetric spectra of this star with FORS2 to search for a rotation period and to constrain the geometry of the magnetic field. We measured longitudinal magnetic fields on 13 different epochs distributed over 62 days. These new measurements together with our previous measurements of the magnetic field in this star were combined with available photometric observations to determine the rotation period. The search of the rotation period resulted in P=42.076+-0.01d. According to near-infrared imaging studies the star is observed nearly edge-on. The star exhibits a single-wave variation of the longitudinal magnetic field during the stellar rotation cycle. These observations are usually considered as evidence for a dominant dipolar contribution to the magnetic field topology., Comment: 6 pages, 7 figures, 1 table, accepted for publication as a Letter in A&A

Context: There is considerable interest in the helium variable a Cen as a bridge between helium-weak and helium-strong CP stars. Aims: We investigate Ce III and other possible lanthanides in the spectrum the of hottest chemically peculiar (CP) star in which these elements have been found. A {Kr II line appears within a broad absorption which we suggest may be due to a high-level transition in C II. Methods: Wavelengths and equivalent widths are measured on high-resolution UVES spectra, analyzed, and their phase-variations investigated. Results: New, robust identifications of Ce III and Kr II are demonstrated. Nd III is likely present. A broad absorption near 4619[A] is present at all phases of a Cen, and in some other early B stars. Conclusions: The presence of lanthanides in a Cen strengthens the view that this star is a significant link between the cooler CP stars and the hotter helium-peculiar stars. Broad absorptions in a Cen are not well explained., Comment: Research Note accepted by Astronomy and Astrophysics; 4 pages, 4 Figs. 2 Tables

Context: Recent attention has been directed to abundance variations among very young stars. Aims: To perform a detailed abundance study of the Herbig Ae star HD 101412, taking advantage of its unusually sharp spectral lines. Methods: High-resolution spectra are measured for accurate wavelengths and equivalent widths. Balmer-line fits and ionization equlibria give a relation between Teff, and log(g). Abundance anomalies and uncertain reddening preclude the use of spectral type or photometry to fix Teff. Excitation temperatures are used to break the degeneracy between Teff and log(g). Results: Strong lines are subject to an anomalous saturation that cannot be removed by assuming a low microturbulence. By restricting the analysis to weak (<= 20 m[A]) lines, we find consistent results for neutral and ionized species, based on a model with Teff = 8300K, and log(g)=3.8. The photosphere is depleted in the most refractory elements, while volatiles are normal or, in the case of nitrogen, overabundant with respect to the sun. The anomalies are unlike those of Ap or Am stars. Conclusions: We suggest the anomalous saturation of strong lines arises from heating of the upper atmospheric layers by infalling material from a disk. The overall abundance pattern may be related to those found for the Lambda Boo stars, though the depletions of the refractory elements are milder, more like those of Vega. However, the intermediate volatile zinc is depleted, precluding a straightforward interpretation of the abundance pattern in terms of gas-grain separation., Comment: Accepted for publication in Astronomy and Astrophysics; 7 pages, 7 figs., 2 tables

We obtained high-resolution, high signal-to-noise UVES and a few lower quality HARPS spectra revealing the presence of resolved magnetically split lines. HD101412 is the first Herbig Ae star for which the rotational Doppler effect was found to be small in comparison to the magnetic splitting. The measured mean magnetic field modulus varies from 2.5 to 3.5kG, while the mean quadratic field was found to vary in the range of 3.5 to 4.8kG. To determine the period of variations, we used radial velocity, equivalent width, line width, and line asymmetry measurements of variable spectral lines of several elements, as well as magnetic field measurements. The most pronounced variability was detected for spectral lines of He I and the iron peak elements, whereas the spectral lines of CNO elements are only slightly variable. From spectral variations and magnetic field measurements we derived a potential rotation period P_rot=13.86d, which has to be proven in future studies with a larger number of observations. It is the first time that the presence of element spots is detected on the surface of a Herbig Ae/Be star. Our previous study of Herbig Ae stars revealed a trend towards stronger magnetic fields for younger Herbig Ae stars, confirmed by statistical tests. This is in contrast to a few other (non-statistical) studies claiming that magnetic Herbig Ae stars are progenitors of the magnetic Ap stars. New developments in MHD theory show that the measured magnetic field strengths are compatible with a current-driven instability of toroidal fields generated by differential rotation in the stellar interior. This explanation for magnetic intermediate-mass stars could be an alternative to a frozen-in fossil field., Comment: 7 pages, 6 figures, 1 table, to appear in Astronomische Nachrichten

HD 65949 is a late B star with exceptionally strong Hg II at 3984[A], but it is not a typical HgMn star. The Re II spectrum is of extraordinary strength. Abundances, or upper limits are derived here for 58 elements based on a model with Teff = 13100K, and log(g) = 4.0. Even-Z elements through nickel show minor deviations from solar abundances. Anomalies among the odd-Z elements through copper are mostly small. Beyond the iron peak, a huge scatter is found. The abundance pattern of the heaviest elements resembles the N=126 r-process peak of solar material, though not in detail. We find a significant correlation of the abundance excesses with second ionization potentials for elements with Z > 30. This indicates the relevance of photospheric or near-photospheric processes. We explore a model with mass accretion of exotic material followed by the more commonly accepted differentiation by diffusion. That model leads to a number of predictions which challenge future work. Likely primary and secondary masses are near 3.3 and 1.6 M(solar), with a separation of ca. 0.25 AU. New atomic structure calculations are presented in two appendices., Comment: Accepted by MNRAS: 16 pages, 5 figures

We investigate the elemental and isotopic stratification in the atmospheres of selected chemically peculiar (CP) stars of the upper main sequence. Reconfiguration of the UVES spectrograph in 2004 has made it possible to examine all three lines of the Ca II infrared triplet. Much of the material analyzed was obtained in 2008. We support the claim of Ryabchikova, Kochukhov & Bagnulo (RKB) that the calcium isotopes have distinct stratification profiles for the stars 10 Aql, HR 1217, and HD 122970, with the heavy isotope concentrated toward the higher layers. Better observations are needed to learn the extent to which Ca-40 dominates in the deepest layers of all or most CP stars that show the presence of Ca-48. There is little evidence for Ca-40 in the spectra of some HgMn stars, and the infrared triplet in the magnetic star HD 101065 is well fit by pure Ca-48. In HR 5623 (HD 133792) and HD 217522 it is likely that the heavy isotope dominates, though models are possible where this is not the case. While elemental stratification is surely needed in many cases, we point out the importance of including adjustments in the assumed Teff and log(g) values, in attempts to model stratification. We recommend emphasis on profiles of the strongest lines, where the influence of stratification is most evident. Isotopic mixtures, involving the 4 stable calcium nuclides with masses between 40 and 48 are plausible, but are not emphasized., Comment: 16 Pages, 20 Figures, 10 Tables. Accepted for publication in Monthly Notices of the RAS

Powerful astronomical spectra reveal an urgent need for additional work on atomic lines, levels, and oscillator strengths. The star HD 65949 provides some excellent examples of species rarely identified in stellar spectra. For example, the Re II spectrum is well developed, with 17 lines between 3731 and 4904 [A], attributed wholly or partially to Re II. Classifications and oscillator strengths are lacking for a number of these lines. The spectrum of Os II is well identified. Of 14 lines attributed wholly or partially to Os II, only one has an entry in the VALD database. We find strong evidence that Te II is present. There are NO Te II lines in the VALD database. Ru II is clearly present, but oscillator strengths for lines in the visual are lacking. There is excellent to marginal evidence for a number of less commonly identified species, including Kr II, Nb II, Sb II, Xe II, Pr III, Ho III, Au II, and Pt II (probably Pt-198), to be present in the spectrum of HD 65949. The line Hg II at 3984 [A] is of outstanding strength, and all three lines of Multiplet 1 of Hg I are present, even though the surface temperature of HD 65949 is relatively high. Finally, we present the case of an unidentified, 24 [mA], line at 3859.63 [A], which could be the same feature seen in magnetic CP stars. It is typically blended with a putative U II line used in cosmochronology., Comment: ASOS9 Poster (Lund, Sweden, August 2007), to be published in Journal of Physics: Conference Series (JPCS), 6 pages 1 figure

The magnetic, chemically peculiar A-star HR 710 (HD 15144, ADS 1849A, AB Cet) has a close companion in a nearly circular orbit. Its 3-day period is unusually short for such stars. The system emits moderately hard x-rays, which likely come from a white dwarf secondary (ADS 1849Ab). The Sr II spectrum is very strong, and the resonance lines show similar core-nib structure to the stronger Ca K line. We place only loose constraints on a model. There are indications of a lower electron/gas pressure than expected from the star's parallax and brightness. Strong-line profiles and anomalous excitation/ionization indicate significant deviations from traditional models, fixed by Teff, log{g}, and abundances. Weak spectral-line profiles and wavelength shifts probably indicate abundance patches rather than the presence of a secondary (ADS 1849Ab) spectrum. Our UVES spectra are from only one epoch. Additional low-noise, high-resolution spectra are needed. We discuss the spectrum within the context of abundance stratification., Comment: 10 pages, 14 figures; accepted for publication MNRAS; v2: metadata authors corrected

We review the classical observational results for isotopic abundance variations for several elements in CP stars. We concentrate on the "newest" anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige 86. The calcium anomaly is also present in cool, magnetic stars, including the notorious HD 101065, Przybylski's star., Comment: Review presented at the CP/Ap Workshop, Vienna, Austria in September 2007

We present the results of a high spectral resolution study of a few spectroscopic binaries with HgMn primary stars. We detect for the first time in the spectra of HgMn stars that for many elements the line profiles are variable over the rotation period. The strongest profile variations are found for the elements Pt, Hg, Sr, Y, Zr, Mn, Ga, He and Nd. The slight variability of He and Y is also confirmed from the study of high resolution spectra of another HgMn star, alpha And., Comment: 2 pages, 2 figures, to appear in "Precision Spectroscopy in Astrophysics"

Large wavelength shifts of infrared triplet lines of Ca II have been observed in the spectra of HgMn and magnetic Ap stars. They have been attributed to the heavy calcium isotopes, including Ca-48. One member of the triplet, $\lambda$8542, had been either unavailable, or of poor quality in earlier spectra. The present material shows conclusively that the stellar $\lambda$8542 shifts are consistent with an interpretation in terms of Ca-48. We find no relation between isotopic shifts of the Ca II triplet lines, and those of Hg II $\lambda$3984. There is a marginal indication that the shifts are {\it anticorrelated} with the surface field strengths of the magnetic stars. We see sparse evidence for Ca-48 in other chemically peculiar stars, e.g. Am's, metal-poor stars, or chemically peculiar red giants. However, the sample is still very small, and the wavelengths of all three triplet lines, including those in the Sun, show slight positive shifts with respect to terrestrial positions. Some profiles of the Ca II infrared triplet in the magnetic stars show extensive wings beyond a well-defined core. We can obtain reasonable fits to these profiles using a stratified calcium abundance similar to that used by previous workers. There is no indication that either the stratification or the Zeeman effect significantly disturbs the measurement of isotope shifts., Comment: 10 Pages, 11 Figures. Accepted for publication in MNRAS

We present the results of a high spectral resolution study of the eclipsing binary AR Aur. AR Aur is the only known eclipsing binary with a HgMn primary star exactly on the ZAMS and a secondary star still contracting towards the ZAMS. We detect for the first time in the spectra of the primary star that for many elements the line profiles are variable over the rotation period. The strongest profile variations are found for the elements Pt, Hg, Sr, Y, Zr, He and Nd, while the line profiles of O, Na, Mg, Si, Ca, Ti, and Fe show only weak distortions over the rotation period. The slight variability of He and Y is also confirmed by the study of high resolution spectra of another HgMn star: alpha And. A preliminary modelling of the inhomogeneous distribution has been carried out for Sr and Y. Our analysis shows that these elements are very likely concentrated in a fractured ring along the rotational equator. It may be an essential clue for the explanation of the origin of the chemical anomalies in HgMn stars (which are very frequently found in binary and multiple systems) that one large fraction of the ring is missing exactly on the surface area which is permanently facing the secondary, and another small one on the almost opposite side. The results presented about the inhomogeneous distribution of various chemical elements over the stellar surface of the primary suggest new directions for investigations to solve the question of the origin of abundance anomalies in B-type stars with HgMn peculiarity., Comment: 6 pages, 4 figures, accepted for publication in MNRAS

We report abundance excesses of 1.2 and 2.6 dex, respectively, for vanadium and bromine in the hot, peculiar star 3 Cen A. Abundances for these two odd-Z elements have not been previously reported for this star. Taken with previous work, they strengthen the case of the origin of the abundance peculiarities by diffusion., Comment: 4 Pages, 2 tables, 2 figures; accepted by Astronomy and Astrophysics

We present a short atlas illustrating the unusual Ca {\sc ii} K-line profiles in upper main sequence stars with anomalous abundances. Slopes of the profiles for 10 cool, magnetic chemically peculiar (CP) stars change abruptly at the very core, forming a deep "nib." The nibs show the same or nearly the same radial velocity as the other atomic lines. The near wings are generally more shallow than in normal stars. In three magnetic CP stars, the K-lines are too weak to show this shape, though the nibs themselves are arguably present. The Ca {\sc ii} H-lines also show deep nibs, but the profiles are complicated by the nearby, strong H$\epsilon$ absorption. The K-line structure is nearly unchanged with phase in $\beta$ CrB and $\alpha$ Cir. Calculations, including NLTE, show that other possibilities in addition to chemical stratification may yield nib-like cores., Comment: 6 pages, 2 figures, and 8 figures; accepted for publication in ApJS

We compare the results of Balmer-line calculations using recent theory and improved computational algorithms with those from the widely-used SYNTHE and BALMER9 routines. The resulting profiles are mostly indistinguishable. Good fits to the normalized solar Balmer lines H$\alpha$ through H$\delta$ are obtained (apart from the cores) using the recent unified-broadening calculations by Barklem and his coworkers provided that some adjustment for the continuum is performed. We discuss a surprising linearity with temperature of the Balmer line profiles in dwarfs., Comment: Submitted to Astronomy and Astrophysics Better figures at http://astro.lsa.umich.edu/users/cowley