bluuebunny/crossref_metadata_2025 huggingface dataset:
Asteroseismology of Delta Scuti Stars – A Parameter Study
Authors: Templeton M. , Basu S. , Demarque P.
Published: July 2016

We assess the potential of asteroseismology for determining the fundamental properties of individual δ Scuti stars. We computed a grid of evolution and adiabatic pulsation models to study systematic changes in l = 0,1,2, and 3 modes as functions of fundamental stellar properties. Mass has the strongest effect on evolution and on pulsation, followed by the metal abundance. Changes to the helium content have very little effect on the frequencies until near the end of the main sequence. Changes to each of the four parameters change the p-mode frequencies more than they do the g- and mixed-mode frequencies, suggesting that these parameters have a greater effect on the outer layers of the star. We also present pulsation models of FG Virginis, outlining a possible method of locating favorable models in the stellar parameter space based upon a definitive identification of only two modes. We plot evolution models on the (period-period ratio) and (temperature-period ratio) planes to select candidate models, and modify the core overshooting parameter to fit the observed star.
Towards Ensemble Asteroseismology of the Pulsating DB White Dwarf Stars
Authors: Handler G. , Wood M.A. , Nitta A. ,   the Whole Earth Telescope Network of Collaborators
Published: July 2016

The origin of the helium-atmosphere DB white dwarfs is still a matter of debate. In particular, the question is unresolved whether binary evolution produces a significant number of DBs. The pulsating DB white dwarfs (DBV stars) offer a complementary insight into this problem through asteroseismology; DBs descending from binaries will have different interior structures than DBs originating from single stars (Nitta & Winget, 1998).

GD 358 is by far the best-observed pulsating DBV star, and the only one for which asteroseismology has been performed to date. This star’s structure has been shown to be inconsistent with an origin from binary evolution (Nitta & Winget, 1998), but most of the other DBVs are relatively poorly studied.

We therefore analysed archival data on all DBVs and obtained new measurements of stars with very little data available (Table 1), firstly to identify suitable targets for asteroseismological investigations and secondly to examine the pulsation spectra of the DBVs as a group, following the works of Clemens (1994) and Kleinman (1995) on the pulsating DA white dwarfs. Our study also produced new seismological results on individual stars and promising targets for future Whole Earth Telescope (WET, Nather et al., 1990) runs.
Asteroseismic Results from WIRE
Authors: Buzasi D.
Published: July 2016

The failed NASA infrared mission WIRE was successfully converted into a high-precision photometry experiment which operated for 17 months. Below I summarize the mission characteristics and performance, as well as providing some examples of the data obtained.
23rd Cycle of Solar Activity in the Light of 34 Years of Cracow Observations of Solar Radio Emission
Authors: Michalec Adam
Published: July 2016

Systematic daily observations of solar radio emission were started at the Fort Skała Observatory on 1st October 1957. The observations were made at the frequency of 810 MHz first with a 5m radio telescope - and since 1964 with a 7m one; at present they comprise already almost 70 thousand hours of observations (Michalec 1991). During that period there were two longer interruptions in the observations: from 23 September 1963 to 2 February 1964 - due to transferring the radio telescope’s antenna from the top of the Fort to a new site, and from 6 November 1973 to 11 March 1974 - connected with the reconstruction of the receiver. Other, fortunately short, interruptions in the course of observations had no influence on the homogeneity of the series.
Brief Review of Solar Models and Solar Neutrino Experiments
Authors: Morrison Douglas R.O.
Published: July 2016

Solar Evolutionary Models are briefly reviewed and while the models are robust, there are uncertainties in the input data which justify rather larger errors. The 1992 experimental results from GALLEX, SAGE II and Kamiokande are shown to be consistent with calculated fluxes of solar neutrinos whereas the Chlorine results continue to be significantly low though this experiment has a problem with the high variability with time of its results in contradiction to Kamiokande. It is concluded that the evidence for a solar neutrino problem is not compelling and New Physics are not demanded. Further experiments are essential to search for neutrino masses and to study the Sun.
Influence of Rotation on the Stellar Parameters
Authors: Wenske V. , Schönberner D.
Published: July 2016

For several years it has become quite common to derive stellar parameters like effective temperature, Teff, and surface acceleration, g, by means of properly calibrated photometric indices, and to use these values for the derivation of important properties of stellar aggregates (viz. ages, star formation history, distances, etc.). Photometric observations, however, fail to give informations about one important property of a star: its rotational rate!

The main effect of rotation is to increase the size of the star, mainly in the equatorial region, leading to lower surface temperatures and accelerations. Since in non–spherical stars Teff and g depend on the latitude, the observed values, which are, of course, averages over the visible hemisphere, depend on the angle of inclination, i. Collins & Sonneborn (1977) utilized the rigidly rotating stellar models of Sackmann and Anand (1970) to compute emergent fluxes and photometric indices for various stellar masses, inclination angles i and rotational parameters being the break–up rotational rate. These indices, viz. C0 and β, represent then averages over the visible part of the rotally distorted stellar models. Closer inspections indicated also that emergent fluxes and line profiles of rotationally distorted stars can be matched by the predictations of standard model atmospheres to a very high accuray, even for w close to unity (Wenske 1992, Diplom Thesis).
Coulomb Interactions in the Equation of State
Authors: Stolzmann W. , Blöcker T.
Published: July 2016

Various models are used in order to develop an accurate equation of state (EOS) for stellar matter (see e.g. Saumon and Chabrier 1991). The complexity of physical effects, for instance degeneracy, relativity, Coulomb- and non-Coulombic interactions requires detailed knowledge from the many-particle physics.

For many applications it is desirable to have theories for these effects over a wide range of densities and temperatures. One of the main sources of uncertainties in the EOS models is the exchange-correlation contribution at any degeneracy and relativity. Previous investigations determine thermodynamic quantities of a partially (e.g. Graboske et al. 1969, Kraeft et al. 1986, Däppen et al. 1988) or fully ionized (e.g. Hubbard and DeWitt 1985, Ichimaru et al. 1987) plasma, resp. Interpolation procedures (Magni and Mazzitelli 1979, Fontaine et al. 1977) combine both cases in the EOS but show non-continuous behaviour.
Observable Effects of Rotation on Stellar Abundances
Authors: Balachandran Suchitra
Published: July 2016

This is a review of our understanding of the effects of rotation on the stellar interior through an examination of observed surface stellar abundances. First, the evolution of angular momentum from the pre-main sequence through the giant phase is summarized. Attempts are then made to decipher the signature of abundance anomalies due to meridional circulation and rotational braking with reference to available theoretical models. Finally, special cases such as tidally-locked binaries and chromospherically-active giants are examined to determine if their rotational peculiarites have induced abundance anomalies.
Rotational Velocity Dispersion in the Hyades and Other Galactic Clusters From The V Sin I Observations
Authors: Gaigé Yves
Published: July 2016

Let us recall briefly the main points of the theory as developped by Chandrasekhar and Münch (1950): if the axis of rotation of a star is inclined with an angle i to the line of sight, the apparent velocity is given by y = v sin i where v is the true rotational velocity. Assuming that the axes of rotation are randomly distributed in space, the frequency function f(v) of the true velocities may be related to the corresponding φ(y) of the apparent ones by the integral equations:

The central moments of f(v) can be derived directly from the observations by means of (1) without the knowledge of the function itself; for instance, the mean and the mean square deviation are given respectively by:
Absolute Parameter Determination in Low-Mass Eclipsing Binaries. Radiative Parameters for BH VIR, ZZ UMa and CR Cas
Authors: Clement R. , Reglero V. , Garcia M. , Fabregat J. , Bravo A. , Suso J.
Published: July 2016

A new uvby and Hβ monitoring program of low mass eclipsing binaries is currently being carried out in the framework of a 5 year observational program which also involves radial velocity determinations. The scope of this work is to provide very accurate absolute astrophysical parameters: mass, radius and effective temperatures, for main sequence late-type stars. One of the main goals is to improve the mass-luminosity relation in the low and intermediate mass range. A second objective is to perform accurate tests of the most recent grids of evolutionary models. This program is complementary to that currently being in progresss by the Copenhagen group.

In this contribution we present the photometric preliminary results obtained for three of the systems included in our long term survey: BH Vir, ZZ UMa and CR Cas for which, primary eclipses have been observed. Particular attention is paid to the determination of reddening, distances and radiative properties. A more detailed study will be carried out when the light curves and radial velocity measurements are completed
Let Us Begin by Modelling Two Observed Delta Scuti Stars Simultaneously
Authors: Michel E. , Goupil M.J. , Lebreton Y.
Published: July 2016

We consider here two Delta Scuti stars GX Pegasi and V650 Tauri, which show very close masses and evolution stages as infered from photometrical calibration. The se two stars have been observed by the STEPHI team (Michel et al. 1990, Belmonte et al. this procedings) and they appear to be multiperiodic pulsators. For both these stars, an identification of the observed frequencies is proposed, from comparison with adiabatic eigenfrequencies computed for well suited stellar mode ls. This interpretation reveals very different pulsational behaviors despite the sta rs are expected to present very similar internal structures. We report here a first step toward constraining models by improving the fit between the observed and the calculated eigenfrequencies. The effect of overshooting and of the recent enhancement of the opacities are i nvestigated.
Asteroseismological Models with Rotation
Authors: Suran Doru Marian , Oprescu Gabriela
Published: July 2016

The low frequency NRP oscillations are considered in the case of differential rotation. Partial differential equations for adiabatic oscillations are reduced to a system of ordinary equations by means of a truncated spherical-harmonic expansion. The numerical method for solving the system is described. The final model also includes line profile variations (lpv) and posttheoretical mass (pth) calculations for the complete determinations of the physical, chemical, rotational and seismological properties of the stars.
Is It Possible to Determine Whether a Star is Rotating About a Unique Axis?
Authors: Gough D.O. , Kosovichev A.G.
Published: July 2016

Rotating stars are normally presumed to rotate about a unique axis. Would it be possible to determine whether or not that presumption is correct? This is a natural question to raise, particularly after the suggestion by T. Bai & P. Sturrock that the core of the sun rotates about an axis that is inclined to the axis of rotation of the envelope.

A variation with radius of the direction of the rotation axis would modify the form of rotational splitting of oscillation eigenfrequencies. But so too does a variation with depth and latitude in the magnitude of the angular velocity. One type of variation can mimic the other, and so frequency information alone cannot differentiate between them. What is different, however, is the structure of the eigenfunctions. Therefore, in principle, one might hope to untangle the two phenomena using information about both the frequencies and the amplitudes of the oscillations.

We consider a simple model of a star which is divided into two regions, each of which is rotating about a different fixed axis. We enquire whether there are any circumstances under which it might be possible to determine seismologically the separate orientations of the axes.
Short-Term Spectral Variability in the Herbig Ae Star Ab Aur: Preliminary Analysis of Chromospheric Lines
Authors: Böhm Torsten , Catala Claude
Published: July 2016

The Herbig Ae stars are PMS objects of intermediate mass. Their location in the H-R diagram indicates that they are in the radiative phase of their quasi-static contraction toward the main sequence, i.e. that they do not possess outer convective zones, according to the standard stellar evolution theory (Iben, 1965; Gilliland, 1986). In spite of the expected absence of subphotospheric convective envelopes, these stars show remarkable signs of activity: emission in the Mg II h and k lines, presence of the CIV resonance lines at 1550 A and He I 5875.7 A line, Ca II IR triplet in emission, etc... Considering that stellar activity, witnessed by the same type of indicators in other parts of the H-R diagram, is generally attributed to dynamo magnetic fields and/or acoustic waves generated in the convection zone, these active phenomena are quite paradoxical in the Herbig Ae stars.

The main question concerns the origin of their activity: is this activity linked to phenomena occurring within the stars, like e.g. dynamo-generated magnetic fields, or to an external agent, like e.g. a boundary layer between an accretion disk and the stellar surface? We already have some indirect clues that the activity of the Herbig Ae stars might be of magnetic origin (Praderie et al., 1986; Catala et al. 1986) observed a rotational modulation of lines formed in the wind of AB Aur, prototype of the Herbig Ae stars. By analogy with the solar wind, they proposed that the modulation might be due to the corotation of azimuthal structures in the wind, controlled by a surface magnetic field.
Photometric Detection of Low-Order Nrp in Be Stars
Authors: Pavlovski K. , Ružić Ž. , Vujnović V.
Published: July 2016

Period analysis of Be stars 28 Cyg and EW Lac has shown that their photometric variations are multiperiodic. Dominant periods have counterpart in low-order NRP modes identified in the independent line profile studies.
E.V.R.I.S. on Board Mars 94: The First Space Experiment Devoted to Stellar Seismology
Authors: Baglin A. , Weissg W. , Bisnovatyi-Kogan G.
Published: July 2016

The EVRIS experiment is an exploratory mission devoted to stellar seismology. It will observe approximately ten bright stars, for 20 days each, during the cruise of the Russian “MARS 94” mission. The photometer will be able to detect amplitudes of modes as small as a few 10−6 magnitude.
Data Analysis Techniques for Determining High Precision Doppler Shifts Using Iodine Absorption Cells
Authors: Horner S.D. , Brown T.M.
Published: July 2016

Some details of the data analysis used to determine high precision Doppler shifts from data obtained using an absorption cell are briefly discussed.
MMVLBI
Authors: Bååth Lars B.
Published: July 2016

VLBI has now made its breakthrough into the mm-wavelength region and is becoming a viable and important new instrument. In this talk I aim to convince you that VLBI will be an important user of your instruments in the future.
VLBI Observations of H2O and SiO Masers in Late Type Stars
Authors: Takaba H. , Iwata T. , Miyoshi M. , Ukita N. , Kameno S. , Matumoto K.
Published: July 2016

The results of a VLBI observation between Kashima 34 m and Nobeyama 45 m are presented. Water maser at 22.235 GHz and SiO masers at 43 GHz in some late type stars are mapped almost simultaneously. Data reduction is still on the way, then we report mainly for the blocking model of H2O maser.
Probing the AU-Scale Structure of Molecular Clouds
Authors: Marscher Alan P. , Bania Thomas M. , Wang Zhong
Published: July 2016

Monitoring absorption lines in the radio spectra of compact extragalactic sources that lie behind local molecular clouds provides a method for exploring the AU-scale structure of the foreground clouds.
The Nobeyama Millimeter Array Survey for Protoplanetary Disks Around Protostar Candidates and T Tauri Stars in Taurus
Authors: Ohashi Nagayoshi , Kawabe Ryohei , Hayashi Masahiko , Ishiguro Masato
Published: July 2016

The Nobeyama Millimeter Array Survey for protoplanetary disks has been made for 19 protostellar IRAS sources in Taurus; 13 were invisible protostars and 6 were youngest T Tauri stars. We observed the 98 GHz continuum and CS(J=2-1) line emissions simultaneously with spatial resolutions of 2.8”- 8.8” (360 AU-1,200 AU). Unresolved continuum emission was detected from 5 of 6 T Tauri stars and 2 of 13 protostar candidates. The continuum emission arose from compact circumstellar disks. Extended CS emission was detected around 2 T Tauri stars and 11 protostar candidates. There is a remarkable tendency for the detectability for the 98 GHz continuum emission to be small for protostar candidates. This tendency is explained if the mass of protoplanetary disks around protostars is not as large as that around T Tauri stars; the disk mass may increase with the increase of central stellar mass by dynamical accretion in the course of evolution from protostars to T Tauri stars.
Molecular Superclouds in M51
Authors: Tosaki T. , Kawabe R. , Taniguchi Y.
Published: July 2016

Recently, it has been shown that some of nearby spiral galaxies have very massive (107-8Mʘ) and large (several 100 pc - ~ 1 kpc) molecular gas clouds (M51: Rand & Kulkarni 1990; NGC1068: Planesas et al. 1991). Since these clouds are significantly more massive and larger than those of so-called Giant Molecular Clouds (GMCs) found in our Galaxy, they are called Molecular Super-clouds (Rand & Kulkarni 1990; hereafter MSCs). In order to study observational properties of MSCs, we present the results of high-resolution (4”) 12CO(J=1-0) mosaic mapping of central 2.’5 region of the Sbc galaxy M51 using the Nobeyama Millimeter Array (NMA). Our main results are summarized in the followings (Tosaki, Kawabe & Taniguchi 1992).
A Vertical Structure of the Edge-On Galaxy, NGC 891
Authors: Handa Toshihiro , Sofue Yoshiaki , Ikeuchi Satoru , Ishizuki Sumio , Kawabe Ryohei
Published: July 2016

Most of observational researches on molecular gas in galaxies have focused on the two-dimensional distributions in galactic disks so far. In order to investigate vertical structure of the galactic disk and the disk-halo interaction we need high-resolution observations of edge-on galaxies.

So we observed the nearest edge-on galaxy, NGC 891, using the Nobeyama Millimeter Array (NMA). Its distance is estimated to be 8.9 Mpc using the Tully-Fisher relation and H-band photometric data. The synthesized beamsize was 4.5” x 4.4” and the field of view due to attenuation of the element antenna (Handa et al. 1992). The field center is 90”-offset from the center of the galaxy along the major axis toward the northern side, where the CO intensity has a local maximum (Sofue et al. 1987). After the standard data reduction procedure in AIPS, including CLEAN, we obtained 10 channel-maps with a 19.5 km s−1 velocity width from 289.8 km s−1 to 465.2 km s−1 with respect to the local standard of rest.

In the integrated intensity map a narrow CO emission ridge is seen (Figure 1). It is an edge-on view of molecular gas disk of the galaxy. The confinement of the CO emission in the thin disk suggests that most of the molecular gas is belonging to the population-I objects like in our Galaxy. The apparent thickness of the ridge is about 7”, which means that the deconvolved width is about 6” or 270 pc (FWHM). The position-velocity diagram averaged along the major axis over the field of view shows no systematic velocity gradient along the minor axis (Figure 2). It means that the deconvolved thickness of the CO disk is intrinsic. This width is broader than that of our Galaxy by factor 2. The geometrically thick CO disk of NGC 891 may be due to active star formation in the disk.
Abundances in Magnetic Ap Stars
Authors: Cowley Charles R.
Published: July 2016

The spatial inhomogeneities, Zeeman broadening, and extreme abundance anomalies have thus far prevented definitive analyses of magnetic CP stars. Nevertheless, the abundance anomalies are so large that many of them have been known for decades. Abundance excesses of iron-peak elements of factors of 10 to 100 are common. Relative abundances on the iron peak are not constant. The lines of vanadium and nickel are often weak, and these elements may even be deficient in some stars. In spitè of the large variations, the odd-even effect persists; there is only minor evidence that chemical separation has perturbed the nuclear pattern. The lanthanide rare earths can have excesses of 100 to 1000 or even more in extreme cases. For these elements there is some evidence of fractionation. The actinide rare earth elements uranium and thorium are weakly (but surely!) present in a few of the magnetic CP stars: the best case is HR 465.
Abundances of Heavy Elements in CP Stars
Authors: Sadakane K.
Published: July 2016

Recent determinations of abundances of heavy elements in CP stars are examined. An emphasis is placed on those elements which are found in a group of CP Stars but not in others. Fragmentary data are available for most of heavy elements. Systematic surveys (especially in the UV region) using a large sample of stars are needed before we understand the physics of the apparently erratic behavior of heavy elements in CP stars.
A New Opacity-Sampling Model Atmosphere Program for Arbitrary Abundances
Authors: Kurucz Robert L.
Published: July 2016

I have developed a new version of my model atmosphere program called ATLAS12. It recognizes more than 1000 species, each in up to 10 isotopic forms, including all ions of the elements up through Zn and the first 5 ions of heavier elements up through Es. The elemental abundances are treated as variable with depth. ATLAS12 has 6 input files of line data containing 58,000,000 atomic and molecular lines. For each line the wavelength, identification, lower energy level, gf, radiative, Stark, and van der Waals damping constants are packed into 16 bytes. At each wavelength point in a frequency integration the profiles of all the significant nearby lines are computed and summed. The program and line files will be distributed in the fall of 1992.

There are no significant differences at A0 between an opacity-sampled model computed with ATLAS12 and opacity-distribution-function model computed with ATLAS9. ATLAS12 allows arbitrary abundances but is slower. The new program can be used to produce improved models for Am and Ap stars that include the effects of millions of lines.
Zeeman Doppler Imaging
Authors: Wehlau William , Rice John
Published: July 2016

The mapping of stellar surfaces using the observed profiles of spectral lines is described. The problem is expressed in terms of an integral equation to be solved, using Tikhonov’s method. The local line profiles may be given either by an analytic approximation or by the solution of the equation of transfer with a model atmosphere. The model atmospheres commonly used may not correctly represent the stellar atmosphere which may lead to errors in the derived surface maps. Tests of mapping programs and applications to real stars show the capabilities and limitations of surface mapping. Mapping stellar magnetic fields places more severe demands on the data and computational programs than mapping the abundance distributions.
Mapping the Surface Distribution of Elements on Ap Stars Using the Maximum Entropy Method
Authors: Hatzes Artie P.
Published: July 2016

A technique for deriving the distribution of elements on the surface of Ap stars using maximum entropy reconstruction principles is described. The technique is applied to deriving the silicon distribution on 56 Ari, CU Vir, 11 Ori and the chromium distribution onϒ2Ari. Silicon on these stars is depleted at the magnetic poles and is enhanced in regions between the magnetic equator and poles. The chromium distribution onϒ2Ari is markedly different than the chromium distribution seen on other Ap stars. It shows depletions at one of the magnetic poles (as do other Ap stars) but it does not show the depleted band at the equator as has been seen onθAur, 45 Her, andωHer. The silicon distribution on 11 Ori also differs from that found on other stars in that it shows evidence for a depleted band, similar to what has been seen in the chromium distribution is some stars. Characteristic features in the abundance maps such as spots or bands appear to mark the location of the magnetic poles or equator so that these maps can be used to infer the magnetic field geometries on these stars. Dipole decentering parameters derived from the abundance maps yield decentering parameters of about 0.2 stellar radii. The amount of decentering seems to be correlated with rotation period (longer period Ap stars have less decentering). Horizontal diffusion can complicate the use of abundance maps to determine the field geometry. The effects of horizontal diffusion can only be understood by a proper theoretical study of its effects or by mapping the elemental distribution on Ap stars of known age.
Determination of Stellar Magnetism Based on the Computerized Evaluation of Zeeman-Spectra
Authors: Gerth Ewald
Published: July 2016

A package of computer-programs is presented, which is suited for the evaluation of stellar spectra in regard of line positions in order to determine the magnetic field strength and the radial velocity. The programs have been developed for the calculation of the measuring data obtained from photographic spectrograms but could be generalized for the online observation in a spectrograph at the telescope using an electronic detector.

The network of programs may be amplified deliberately as required for any special application. For the exchange of data among cooperating institutes we propose the standardization of programs and data-files as outlined below.
Search for Magnetic Fields in Vega, Gamma Geminorum, and Sirius
Authors: Takada-Hidai Masahide , Jugaku Jun
Published: July 2016

Magnetic fields in Vega, ϒ Geminorum, and Sirius are searched by using empirical and theoretical relations of magnetic-field strength to the relative differences between the equivalent widths of each pair of the two Fe II lines near 6150 and 4400 Å. We estimated the possible strengths of their magnetic fields as follows: 0.0 kG or 2.5 – 3.5 kG for Vega, 0 – 2 kG or 2.8 – 3.0 kG for ϒ Gem, and 0.0 kG or ∼ 2(?) – 2.5 kG for Sirius. The empirical relation yields the former value in each star, which is consistent with those determined through polarization measurements, while the theoretical relation the latter with systematically large values.
Variability Among Magnetic and Nonmagnetic Stars
Authors: Schöneich Werner , Želwanowa Elia
Published: July 2016

The present paper concentrates on several seemingly nonstandard cases of variability related to CP stars. Variability of magnetic CP stars with time scales different from rotational period, variability among the HgMn stars, variability of normal stars with variations similar to CP stars, and a relation between Be and CP stars are shortly discussed.
Carbon and Silicon in Normal a Stars and in Lambda Bootis Stars
Authors: Holweger Hartmut , Stürenburg Sven
Published: July 2016

The anticorrelation of C and Si previously inferred from high-resolution spectroscopy of sharp-lined A stars classified as normal or mild Am is also found among the metal-deficient, more rapidly rotating λ Boo stars. The entire sample of program stars covers the range [C/Si] = − 1.14 (Sirius, mild Am star) to + 1.35 (HR 7400, λ Boo-type). Iron varies parallel with silicon. With respect to surface chemistry the λ Boo stars do not form a distinct group but rather represent the lower end in a continuous sequence of ‘metal’ abundance extending over more than 1.5 dex.

We argue that differential accretion of gas and dust in late stages of star formation or during the main-sequence phase is responsible for most of the abundance variations of the lighter elements up to the iron group. Enhanced or impeded accretion of dust leads to a metal-rich or metal-poor surface composition, respectively. The heavy trace elements Sr and Ba show additional anomalies indicating that other processes like gravitational and radiative separation are also involved.
A Search for λ Bootis Stars in OB Associations
Authors: Gray R.O. , Corbally C.J.
Published: July 2016

A search for λ Bootis stars in two OB associations (Orion and Lacerta OB1) has been carried out. One clear example of a ZAMS λ Bootis star has been discovered in Orion OB1. Both Orion OB1 and Lacerta OB1 contain, as well, a number of mildly metal-weak A-stars which may be λ Bootis stars in-the-making.
Long Term Variability in CP Stars
Authors: Hensberge Herman
Published: July 2016

A search for CP2 stars with long photometric periods during more than one decade has led to the detection of the long period variables HD 94660 and HD 116458. Furthermore, in the case of ϒ Equ, the CP star with the longest magnetic period, a monotonic change of the light output has been measured. Light curves are presented for the known long period variables HD 187474 and HD 188041. The results on the other stars in the programme are shortly discussed.
Chemically Peculiar Stars in Clusters: Upper and Lower Age Limits of CP Stars
Authors: North P.
Published: July 2016

The evolutionary state of CP Stars is defined using members of open clusters. It is confirmed that all CP stars belong to the main sequence, if the case of Horizontal-Branch Stars is omitted. The frequency of CP Stars as a function of age has been reconsidered: it is found constant for the CP2 stars, but significantly increasing with age for the CP1 (Am) stars.
Photometric Properties of CP Stars in the Infrared
Authors: Catalano Francesco A. , Leone Francesco , Kroll Reinhold
Published: July 2016

Eightysix chemically peculiar stars have been observed in the near infrared with the aim to extend the comprehension of the differences between normal and peculiar stars. These stars have been checked for variability. Most of the stars are previously known light variables, although their periods were not accurate enough to phase together different kinds of observations carried out several years apart. For about 20 stars the period has been refined by combining our own uvby observations with the ones available in the literature.
An Empirical T – τ Curve for the Roap Star HR 3831: Atmospheric Structure from Pulsation Amplitudes
Authors: Matthews Jaymie M. , Wehlau William H. , Rice John , Walker Gordon A. H.
Published: July 2016

The atmospheric structures of magnetic CP2 (Ap) stars are notoriously difficult to model: line blanketing is severe, surface gravities are extremely uncertain, and the surface abundance inhomogeneities lead to different atmospheric properties as a function of position on the star. Seismology of the p-modes of rapidly oscillating Ap (roAp) stars (Kurtz 1990), which vary with periods of a few minutes and amplitudes below 0.01 mag and 1 km/s in light and velocity, has already helped constrain the luminosities – and hence, the logg values – of some cool CP2 stars (Kurtz 1992, these proceedings). We show here that the pulsations of an roAp star can also directly probe the temperature structure of a CP2 atmosphere.
Age Determination for Am Stars
Authors: Figueras F. , Torra J. , Jordi C. , Asiain R.
Published: July 2016

From uvby and Hβ photometry, individual stellar ages for A type stars have been derived using three different evolutionary models. In this paper we evaluate the corrections for metallicity and rotation to be applied to the physical parameters of Am and their influence on the determined ages. A test based on the Hyades open cluster is also presented.
Atomic Opacities
Authors: Seaton M. J.
Published: July 2016

LetIv(r, θ) be the intensity of radiation of frequencyv, at a distancerfrom the centre of a star and in a direction making an angleθto the outward normal. In a plane-parallel approximation the equation of radiative transfer is

where𝛋vis the opacity andjvthe emissivity. The net outward flux of radiant energy is

and the flux integrated over all frequencies is
Ab initio Calculations of Absorption Coefficients of Small Carbon Hydride Molecules
Authors: Peyerimhoff S.D.
Published: July 2016

Quantum chemical methods have become a powerful tool for investigating the electronic structure of small molecules in ground and excited states. This is particularly true for species which are not easily accessible by experiment, either because they are short-lived, for example, or unstable under laboratory conditions or difficult to detect since their signals are hidden by other, prevailing molecules. In this sense theoretical methods are of special importance for molecules in atmospheric, stellar and interstellar environments.
Proper Motions from Schmidt Plate Scans at STScI
Authors: MacConnell D. Jack , Roberts Wm. James , Williamson Ramon L.
Published: July 2016

We describe a program of determining proper motions from digitized scans of Palomar Oschin Schmidt telescope plates at the Space Telescope Science Institute. Our method is most useful over 11 ≲ V ≲ 18 and .
The Stellar Space Distributions of dA and gK Stars
Authors: Dawanas D. N. , Hidayat B.
Published: July 2016

We present a case study on the stellar space distribution of stars with MK spectral types B8 to A2 (dA) and gG8 to gK2 (gK) in a sky region of 25 square degrees, centred at the galactic coordinate l = 4° and b = +12°. Two hundred and forty-eight (248) stars with MK type of B8–A2 and gG8–gK2 were identified in this field. The space density distributions of these stars were obtained by employing the Matrix and Malmquist methods. The relative density of B8–A2 stars tends to be similar to that of gG8–gK2 stars, which implies that the two groups of stars occupy the same space volume in the galaxy. The comparison with those of Field-3 (l = 0.8°, b = –10°) show that the space density distribution of the two groups of stars above and below the galactic plane is not the same. Above the galactic plane, the space density of the gK stars is higher than those of dA stars, whereas below the galactic plane the density of dA stars is higher than for the gK stars. For both groups, the maximum space density occurs at around 30–40 pc from the galactic plane.
A Survey of Emission-line Stars in the Outer Part of the Orion Star-forming Region
Authors: Wiramihardja Suhardja D. , Nakano Makoto , Kogure Tomokazu
Published: July 2016

We report the result of our survey observations in the outer part of the Orion star-forming region which consists of six Kiso sky areas (150 square degrees). In total, we detected only 48 emission line stars. The low surface density suggests that the Orion star-forming region probably terminates around these areas.
Observational Constraints on Cosmological Models
Authors: Padmanabhan T.
Published: July 2016

Cosmological models for structure formation are severely constrained by several of the recent observational results. We now have observations which probe the power spectrum of fluctuations from about 0.5 h−1 Mpc to 3000 h−1 Mpc. These probes and the constraints they imply on models for structure formation are reviewed.
3D Spectroscopy with large Telescopes: past, present and prospects
Authors: Monnet G.
Published: July 2016

The dimensional curse of having to pack 3D spectrophotometry data on solely 2D detectors is briefly discussed, and the main astronomical domains covered by 3D spectroscopy introduced. Finally, the scientific case for high spatial resolution 3D techniques coupled to Adaptive Optics capabilities is presented, with special emphasis on the observation of the nuclei of galaxies.
An Expanding Ring in the Gaseous Disk of NGC 6181?
Authors: Boulesteix J. , Sil’chenko O. K. , Zasov A. V. , Burenkov A. N.
Published: July 2016

The Sc-galaxy NGC 6181 was observed at the 6m telescope with the Fabry-Perot interferometer CIGALE in Hα emission. A ring-like zone of strong radial gas motions at the radius of 1.8 kpc was found.
Tridimensional spectroscopy of Seyfert Galaxy 3C 120
Authors: Kosugi G. , Ohtani H. , Yoshida M. , Aoki K.
Published: July 2016

Tridimensional spectroscopy of the Seyfert 1 galaxy 3C 120 was carried out with Spectronebulagraph (SNG). We constructed a data cube which is free from atmospheric variations during the scans. We then separated the blended lines by deconvolving the line profiles, to obtain pure narrow-line images and narrow-line intensity ratio diagram.
Integral field spectroscopy with optical fibres
Authors: Vanderriest C.
Published: July 2016

An efficient technique for obtaining complete spectral informations over moderately extended objects is to transform the geometry of their telescopic images to match a classical long ”slit” aperture. This anamorphosis is conveniently made with bundles of optical fibres. Such devices are especially useful when high spatial resolution and large wavelength coverage are required at the same time. We review the existing instruments based on this technique and present some typical results. We discuss also the future developments of integral field spectroscopy with optical fibres (visible or IR domains) for the new generation of very large telescopes.
Clues for stellar formation in NGC 1275 cooling flow
Authors: Ferruit Pierre , Pécontal Emmanuel
Published: July 2016

3D spectrography of the inner regions of NGC 1275 has been performed using the integral field spectrograph TIGER. It revealed an association between star clusters and some line emitting gas components, likely to be filaments material. This may indicates that the clusters originate from star formation in the cooling flow
Study of Central Regions of AGNs at 6-meter Telescope
Authors: Afanasiev V. L. , Shapovalova A. I. , Burenkov A.N. , Dodonov S. N. , Vlasiouk V. V.
Published: July 2016

Kinematic investigations of the central (10″×10″) regions of the Seyfert galaxies NGC 4151 and Mkn 573 on the 6-m telescope with 3D-spectroscopy methods are presented.
Impact of nuclear activity on extended emission line regions of nearby galaxies
Authors: Pécontal E. , Ferruit P. , Wilson A.S.
Published: July 2016

We used the integral field TIGER to map the intensity ratios of emission lines and the velocity field over the narrow emission line of a few nearby Seyfert galaxies. Our aim is to study the impact of nuclear activity on galaxies, which will hopefully help us to probe the central engine. We present here some results for two objects: M 51 and NGC 5929.
Integral Field Spectrograph Observations of NGC 4258
Authors: Afanasiev V.L. , Courtes G. , Dodonov S.N. , Plana H.
Published: July 2016

The nuclear region of the NGC 4258 was observed at the 6m Telescope using an integral field spectrograph. Monochromatic maps in Ha and [NII] 6548/6583 Ålines were constructed from the data. Based on monochromatic maps and a velocity field with spatial sampling 0.6 arcsec, and the data published by Courtes et al., (1993) and Cecil et al., (1993) data, we tried to reconstruct the structure of the outflow.
Sub-resolution limit spatio-spectral information using Differential Speckle Interferometry
Authors: Lagarde S. , Sánchez L.J. , Petrov R.G.
Published: July 2016

Differential Speckle Interferometry (DSI) combines high angular resolution techniques with medium to high resolution spectroscopy. For non resolved sources, it yields the displacement of the object photocenter with wavelength. Combined with the spectrum s (λ), can give information with spatial and/or spectral resolution well beyond the telescope or spectrograph limits. This complementarity is illustrated here with experimental results. For the binary system Capella, we measure the angular separation, separate the spectra of the components and derive the radial velocity difference and the rotation velocity of each component. For the slowly rotating star Aldebaran we obtain the position angle of the stellar rotation axis and a relation between the angular diameter and the rotation velocity which in this case gives the latest.
Turbulent and Ordered Motions in HII Regions
Authors: Courtès G.
Published: July 2016

The Fill regions morphology have suggested, from the beginning of this century, the evidence of internal motions, very few gas radial velocities (RV) on the brightest “nebulae” had been obtained, because of obvious technical difficulties. The modern Fabry-Perot interferometers and the new integral Field Spectrograph provide abundant RV fields at various scales in the interstellar gas. New ways in imagery, owing to these new instruments, lead to a better analyse of both, the velocities field and their precise morphology free of stellar, dusty, and non thermal continua. The richness and the guallty of RV data, a better understanding of the expansion phenomena authorize again a rebirth of the turbulence observations of the ionized interstellar gas.
Turbulent Mixing in Wind-Blown HII Regions
Authors: Breitschwerdt D. , Kahn F.D.
Published: July 2016

Turbulent mixing between an ionization bounded HII region and a hot shocked stellar wind (HSSW), which keeps it under pressure, is examined. Recently we have shown that acoustic disturbances can grow there to finite amplitude in a time scale which is comparable to the sound crossing time in the HII layer. The resulting turbulence will then stretch fluid elements and the frozen-in magnetic field. A condition under which turbulence can decay down to the viscous scale, where mixing is very efficient, is derived. For a uniform and plane parallel magnetic field Bo and a constant density ρo of the ambient medium, we find that efficient mixing takes place near the polar regions. Subsequently the rate of mass addition to the hot bubble is calculated and it is shown that catastrophic cooling is likely to occur. In the case of NGC 6334(A) it seems that this has just happened and we predict an upper limit for Bo of 4 x 10-5 gauss there. This model may also explain the existence of highly ionized species (e.g. OVI), soft X-rays and high velocity flows of the order of 100 km/s.
Accretion Flows in High-Mass Star Formation
Authors: Keto Eric
Published: July 2016

We compare observed and simulated images of the accretion flows associated with high mass star formation in the regions G10.6-0.4 and DR21. We describe, as a result of the comparison, the temperature, density, and velocity fields. Our results indicate that the G10.6-0.4 cloud core is strongly condensed and has approximately equal velocities in rotation and infall at its current evolutionary state. The rapid collapse and lack of rotational support suggests that significant angular momentum transfer is occuring over scales at least as large as those observed (0.5 pc). A milligauss magnetic field would have sufficient energy to supply the required braking torque of 1047 ergs. The DR21 core shows approximately spherically symmetric radial accretion with no detectable rotation. Unlike the G10.6-0.4 core, the DR21 core does not contain an embedded HII region. Thus this core may represent a molecular cloud condensation undergoing gravitational collapse and accretion just prior to the formation of massive stars.
Aperture Synthesis Observations of CS, NH3, and Continuum in the Bipolar Flow Source NGC2071-IRS
Authors: Kawabe R. , Kitamura M. , Ishiguro M. , Hasegawa T. , Chikada Y. , Okumura S. K.
Published: July 2016

We have made aperture synthesis observations of CS(J=l-0, 2-1) and NH3(1,1) lines and 49, 98, and 110 GHz continuum in NGC2071-1RS with the Nobeyama Millimeter Array. Wfe have obtained maps of these lines and continuum maps with 2”. 7-20” resolution, ffe have found that dense molecular gas has a disk structure with a radial scale ranging 0.01 pc - 0.1 pc and has a ring-like structure with expanding motion at the central 5000 AU region. We also have found that there exists double dust continuum sources which are separated by 2500 AU in projection and are apparently located at the inner edges of the ring. Our observational results suggest that the disk of molecular gas has a central hole formed by wind and UV radiation from a central young stellar object, the central part is expanding, and that dust continuum emission comes from tangential parts of the shock compressed ring (r~1300 AU, M(H2)~ 21-34 Mo, and n(H2)~ 109) at the most inner side of the disk structure. The other possible model of the dust continuum sources is a binary system of self-luminous young stellar objects.
Inflow of Neutral Gas toward the Galactic Disk
Authors: Mirabel I.F.
Published: July 2016

I highlight the evidence for inflow of neutral gas toward the disk of the Galaxy. The Milky Way is accreting 0.2-0.5 M⊙/yr of extragalactic atomic hydrogen at very high velocities. The interaction of infalling clouds with galactic material produces large-scale disturbances in the interstellar medium. Although the injection of energy into the galactic disk by infalling neutral gas is only 1% of the energy from supernovae, the impinging of high velocity neutral gas may be a relatively important source of energy in localized regions of the outer Galaxy.

In the solar neighborhood the downfall rate of HI at intermediate velocities is 2.72 x 10-8z-1(kpc) M⊙pc-2yr-1, which if representative of the whole galactic disk, is at least 10 times more massive than the estimated accretion rate of extragalactic HI at very high velocities. This implies that most of the neutral gas that is infalling in the solar vicinity has originated in the galactic disk. It is concluded that in the Milky Way galaxy there is a moderate inflow of extragalactic neutral gas on top of a more intensive disk-halo circulation.
The Nal Interstellar Spectrum of HVC 287.5 + 225 + 240
Authors: Molaro P.
Published: July 2016

We present high resolution (FWHM≈7 km/sec) and high signal-to-noise observations of the bright Seyfert galaxy NGC3783 obtained with the CES spectrograph linked by fibres to the 3.6m telescope at La Silla, Chile.
The Mass Spectrum of Interstellar Clouds
Authors: Dickey John M. , Garwood R. W.
Published: July 2016

The abundance of 21-cm absorption lines seen in surveys at high latitudes can be translated into a line of sight abundance of clouds vs. column density using an empirical relationship between temperature and optical depth. As VLA surveys of 21-cm absorption at low latitudes are now becoming available, it is possible to study the variation of this function with galactic radius. It is interesting to compare the abundance of these diffuse atomic clouds (with temperatures of 50 to 100 K and masses of 1 to 10 M⊙) to the abundance of molecular clouds. To do the latter we must make assumptions about cloud cross-sections in order to convert the line of sight abundance of diffuse clouds into a number per unit volume, and to convert from cloud column density to mass. The spectrum of diffuse clouds matches fairly well the spectrum of molecular clouds, although observationally there is a gap of several orders of magnitude in cloud mass. Optical absorption studies also agree well with the 21-cm results for clouds of column density a few times 1020 M⊙.