bluuebunny/crossref_metadata_2025 huggingface dataset:
High- and Low-Degree Modes in Delta Scuti Stars: 1- and 2-D Fourier Analyses Of τ Peg
Authors: Kennelly Edward J. , Matthews Jaymie M. , Walker Gordon A.H.
Published: July 2016

Stellar seismology of δ Scuti stars offers the best prospect for determining the interior properties of normal non-magnetic A-F stars on or near the main sequence. The discovery of rich eigenfrequency spectra in the light variations of several δ Scuti stars (e.g., θ2 Tau: Breger et al. 1989; GX Peg: Michel et al. 1990) should make this possible for low-degree modes (l ≤ 4). However, due to cancellation effects, modes of higher l cannot be studied through photometry or radial velocity measurements.

The detection of rapid line-profile variations among rapidly rotating δ Scuti stars (e.g., Walker et al. 1987; Kennelly et al. 1992) has extended our sensitivity to much higher modes. These variations are consistent with moderate- to high-degree modes, where |m| ~ l. (In the simplest case, they could be pure sectorial modes with |m| = l and pulsation amplitudes strongly confined to the stellar equator.) To use these data effectively, we need an objective way to identify the modes and their time evolution.
Impact of Observations on Prejudice and Input Physics
Authors: Gough D.O.
Published: July 2016

My brief from the principal organizers of this colloquium is to draw your attention to some of the prejudices upon which the observations that have been discussed here have had or should have had some impact, and to remark on how that might revise our views about physics: it should not be a balanced summary of the meeting, but a prejudiced review.
Key Issues: A Round Table Discussion
Authors: Brown T.M. , Demarque P. , Noyes R. , Praderie F. , Roxburgh I.W. , Schatzman E.
Published: July 2016

We have taken part to an exceptionally rich colloquium, characterized by a large amount of information in all fields of physics, and a remarkable collection of observational data. Our understanding of what is going on inside the stars has changed in a radical manner during the last years, on one side because the observations are bringing new kinds of information, and on the other side because theory in its development is taking into account a number of processes, some of them having been completely ignored only ten years ago.

It is impossible to draw here a complete list of problems. There are many cases where some inconsistency could be found in the theory itself or some contradiction between observational data and theory. I recommended that such a list should be drawn carefully. The participants to the round table discussion will give their contribution, helping to open the way to new fields of research and to new discoveries.
Chemical Evolution of Algol-Type Stars
Authors: J.Sarna Marek
Published: July 2016

The evolution of the chemical abundances at the surface of both components of Algol-type binaries is examined. First, we have examined some mixing processes which can affect element distribution in components of Algol-type stars. Second, the C abundance determinations from theoretical models are compared with values known from observational analysis. We conclude that there is no significant difference in chemical composition in components between case AB and early case B mass transfer. We have found a real difference between systems which evolve from initial mass ratios of 10/4 and 10/9.
A New Model for the Structure and Evolution of Main Sequence Stars
Authors: Vera Rafael A.
Published: July 2016

From both astronomical facts and theory it is inferred that the primary energy of main sequence stars most probably comes from gravitational work around a neutron star. The new mechanisms involved can in principle account for the observed facts, including those unconsistent with conventional models.
Microarcsecond VLBI: What will We See?
Authors: Valtaoja Esko
Published: July 2016

With the exception of some pioneering mm-VLBI observations, the present-day VLBI cannot resolve the most compact components in active galaxies, nor measure their brightness temperatures. In addition, the observing frequencies are too low: the innermost components are still self-absorbed and often completely undetectable at standard VLBI frequencies. However, studies of continuum spectra and variations of AGN can give us estimates of what will eventually be seen when VLBI techniques reach sufficient resolutions and frequencies. These estimates are also useful in considering what capabilities will be required from future interferometry for studying AGN.

We have used multifrequency continuum monitoring data together with standard shock-in-jet models to derive flux, size and brightness temperature distributions for the innermost core components in a complete 2 Jy sample of AGN. The millimeter spectra and its variations can be satisfactorily explained by just two types of high-frequency components, a relativistic inhomogeneous jet and evolving shocks in this jet (Valtaoja et al. 1988). Moreover, with extended multifrequency flux monitoring the contributions from these two components can be separated, which makes possible the extraction of limited amounts of structural data (average sizes, brightness distributions, etc.) just from continuum data.

We have used two main methods. Cm-to-mm spectra can reveal the existence of persistent high frequency components and give estimates of their fluxes and turnover frequencies. Continuum monitoring gives fluxes and variability timescales of transient components, and further their sizes and brightness temperatures.
MM-VLBI Survey of Spectral Index on AGN
Authors: Matsumoto K. , Kawaguchi N. , Inoue M. , Takaba H. , Koyama Y. , Iwata T. , Kurihara N.
Published: July 2016

The preliminary results of an mm-VLBI survey of spectral index on active galactic nuclei (AGN) are presented which suggest that their activities are only in the central regions. The difference in central activities may correspond to their different stages of evolution. We found a strong concentration to α = 0 for quasar and a spread distribution for HPQ.
Wide-Band Tunerless Mixer Mounts for 100 GHz and 150 GHz SIS receivers
Authors: Sunada K. , Kawabe R. , Inatani J.
Published: July 2016

The performance of the new SIS receiver systems at the Nobeyama Millimeter Array are described. These receivers operate at 100 GHz and 150 GHz bands and tunerless mixer mounts have been adopted. These receivers show very low noise temperature (< 50 K) over a very wide frequency range because of the large embedding impedance range.
Phase Calibration of the Proposed Millimeter Array
Authors: Holdaway M.A.
Published: July 2016

The phase structure function can be estimated from water vapor radiometer data. We present typical phase structure functions and indicate how residual calibration errors are related to the phase structure function and the calibration parameters. From this, we can estimate the amount of time the array can be used and compare different calibration methods.
Combined-Array Imaging of Extra-Galactic Radio Sources
Authors: Akujor Chidi E. , Bååth Lars B.
Published: July 2016

The resolving powers of existing telescope arrays are quite different. For example the extended new MERLIN at 5 GHz readily yields maps of ~ 50 mas resolution compared with the VLA ~ 350 mas, WSRT ~ 4000 mas, EVN ~ 5 mas, global VLBI ~ 1 mas, etc. This means that images obtained with these instruments yield information on different scales that sometimes appear unrelated. However, the need to have structural information on intermediate scales demands that data from different arrays be combined to make a single image. This is particularly important in extra-galactic radio sources where the relationship between core-jet features on different scales (parsec and kiloparsec) and the connection between small-scale and extended features need to be established.

By combining uvdata from two or more arrays we can routinely make images that represent a balance between the capabilities of the combined arrays, (e.g. VLA + MERLIN, MERLIN+VLBI, VLA+WSRT etc) at cm wavelengths. In order to do this, one has to overcome a number of calibration and mapping difficulties (see Zhang et al. 1991; Akujor et al. 1992, in prep.).
Interferometer Observations of Circumstellar Envelopes with the IRAM Plateau de Bure Interferometer
Authors: Lucas R.
Published: July 2016

We summarize the main results obtained with the IRAM Interferometer on Plateau de Bure during its first years of operation, in the field of circumstellar envelopes.
Molecular Envelopes of Planetary Nebulae and Proto-Planetary Nebulae
Authors: Kwok Sun
Published: July 2016

As stars evolve up the asymptotic giant branch (AGB), they begin to lose mass at a high rate, and in the process they create extended circumstellar molecular envelopes. Since the transition from AGB to planetary nebula stages is of the order of 1000 yr, the remnant of such molecular envelopes should still be observable in pro to-planetary nebulae (PPN) and planetary nebulae (PN). Recent ground-based survey of cool IRAS sources have discovered ~30 candidates of PPN (Kwok 1992). These sources show the characteristic “double-peak” energy distribution. The cool component is due to the remnant of the AGB dust envelope, and the hot component represents the reddened photosphere. The fact that the two components are clearly separated suggests that the dust envelope is well detached from the photosphere. Radiative transfer model fits to the spectral energy distributions of PPN suggest a typical separation of ~1 arc sec between the dust envelope and the photosphere, and such “hole-in-the-middle” structure can be mapped by millimeter interferometry in CO.
Ionized and Neutral Gas in the Central 10 PC of the Galaxy
Authors: Lo K. Y. , Plante R. , Lacy J. , Wright M. , Killeen N.
Published: July 2016

Observations of the 12.8 μm [NeII] line emission, the OH absorption against Sgr A and the HCN emission were compared to determine the relationship between the ionized and neutral gas in the central 10 pc of the Galaxy. The distribution of the neutral gas is too asymmetric to be a ring or disk. Along the western arc, the ionized gas velocity is very different from that of the neutral gas, suggesting it may not be the ionized inner edge of the circum-nuclear neutral gas.
Interstellar Chemistry in Orion KL
Authors: Yamamoto Satoshi , Mikami Hitomi , Saito Shuji
Published: July 2016

A map of SiO (J = 2 − 1) in Ori KL has been obtained with 2.8” spatial resolution by using Nobeyama Millimeter Array. The distribution of SiO evidences an interaction between outflow and dense gas around IRc4 and IRc5; these infrared sources are thus considered to be shock-heated regions. Since distributions of (CH3)2O and HCOOCH3 have a peak at the IRc5 position, such shock heating seems to play an important role in production of these molecules. Detection of CH3OD around the interacting region most likely suggests that CH3OH is evaporating from dust grains. (CH3)2O and HCOOCH3 may be produced by gas-phase reactions starting from injected CH3OH, or they might be evaporated from dust grains.
Evolution of Disks in the Course of Star Formation
Authors: Hayashi Masahiko
Published: July 2016

Observations of circumstellar disks with Nobeyama Millimeter Array (NMA) are presented for the following two topics. The first one is on the continued NMA survey for 13 complete samples of protostar candidates associated with Taurus molecular cloud. The observation confirmed the previous result that protostar candidates do not have detectable 3 mm continuum emission except for the two sources L1551-IRS5 and IRAS 04365+2535. This sets the upper limit to the circumstellar disk mass to be ~0.03 Mʘ for the protostar candidates. The disk mass for protostar candidates tends to be smaller than that around young T Tauri stars, suggesting that it may increase in the course of evolution from protostars into T Tauri stars. The second topic is on the detection of CO (J=1-0) emission toward GG Tau. The observations with the 45-m telescope and with NMA show strong evidence of the CO emission arising from a rotating disk with its size significantly extended with respect to the dust disk. Depletion of CO gas in the GG Tau disk is discussed.
Aperture Synthesis CS(J=1-0) Observations of the Molecular Outflow in NGC 2071: Subclumps in a Wind-Driven Shocked Shell and their Origin
Authors: Kitamura Yoshimi , Kawabe Ryohei , Ishiguro Masato
Published: July 2016

Aperture synthesis CS(J=l-0) observations were made of the expanding clumpy shocked shell that was found around the redshifted CO outflow in NGC 2071 during our previous study (Kitamura et al. 1990). It has been revealed that previously identified clumps in the shell comprise several small subclumps. The decelerating shock and Rayleigh-Taylor instabilities seem to be probable mechanisms by which the subclumps are formed in the shock-compressed shell.
High S/N HCO+ Maps of the Orion B Dense Core
Authors: Barnes Peter J. , Crutcher Richard M.
Published: July 2016

By combining new NRAO 12m data with previously published BIMA data, we have obtained very high signal-to-noise maps of HCO+ in the Orion B core, which contain information on both the large- and small-scale emission and put new constraints on the gas’ physical conditions.
Radiative Transfer Modeling of Molecular Clouds: HCO+ in the Star-Forming Region W 49 A North
Authors: Dickel Hélène R. , Auer Lawrence H. , Wilner David J.
Published: July 2016

A multi-level, non-LTE, (non-LVG) radiative transfer code has been applied to HCO+ observations of W 49 A north. Profiles of both the J=1-0 and J=3-2 transitions are successfully reproduced with a variety of cloud models.
Millimeter Observations of G5.89-0.39
Authors: Wilner David J. , Welch W. J. , Forster J. R. , Murata Yasuhiro
Published: July 2016

We present multi-line millimeter interferometer maps HII single dish observations of the G5.89-0.39 ultracompact HII region. Radiative transfer modelling suggests an overall collapse.
CO Outflows in Low-Mass Protostar Candidates in Taurus
Authors: Tamura M. , Ohashi N. , Moriarty-Schieven G. , Hayashi M. , Hirano N.
Published: July 2016

The Taurus dark cloud is one of the nearest active sites of low-mass star formation. The IRAS satellite has discovered numerous low-luminosity far-infrared sources in this cloud, some of which are completely invisible at optical wavelengths. There are several arguments suggesting that the invisible sources are low-mass protostars which are younger than T Tauri stars and powered by the accretion of infalling gas and dust (Adams, Lada, & Shu 1987; Beichman et al. 1986; Myers et al. 1987; Kenyon et al. 1990)

Tamura et al. (1991) made a near-infrared imaging survey of a complete, flux-limited sample of cold IRAS sources in the Taurus dark cloud, of which 8 are optical T Tauri-like objects and 16 are optically invisible sources. They identified all 24 sources with near-infrared counterparts; one is entirely nebulous without a point-like source, and the others generally have an unresolved peak with or without an extended component at 2.2 µm 75 % of the 24 sample sources are associated with infrared/optical nebulosity about 1000 AU to 10000 AU in size. A number of the sources show a clear bipolar or monopolar morphology, suggestive of a close relation of the nebulosity with a bipolar mass outflow; the nebulosity is due to scattering of light from the central source by the dust associated with the mass outflow extending to the poles of a circumstellar dust disk.
Circumstellar Molecular Gas of the Young Stellar Object SVS 12
Authors: Stapelfeldt Karl R.
Published: July 2016

SVS 12 is an embedded infrared source which is the probable exciting star for HH 12. The source has a “class I” IRAS spectrum and about 20 L© luminosity. Differential reddening between the star (J-K ≥ 6 mag) and the adjacent infrared reflection nebula (J-K= 3 mag) suggests the presence of dense circumstellar material (Stapelfeldt et al. 1991). SVS 12 was observed with the OVRO interferometer in the 13CO 1-0 and CS 2-1 lines and associated continuum, and at the CSO with a bolometer and in the CS 5-4 and CS 7-6 lines.
Rotating Protoplanetary Gas Disk in GG-Tau
Authors: Kitamura Yoshimi , Kawabe Ryohei , Omodaka Toshihiro , Ishiguro Masato , Miyama Syoken
Published: July 2016

A rotating gas disk was discovered around a T-Tauri star, GG-Tau, in Taurus by using the Nobeyama Millimeter Array (NMA) (Kawabe et al. 1993). To analyze the observed data, we have numerically calculated velocity profiles of CO emitted from protoplanetary gas disks by taking account of the line radiative transfer.
Molecular Gas in the Centers of Barred and Starburst Galaxies
Authors: Kenney Jeffrey D. P.
Published: July 2016

High resolution interferometric CO maps of the circumnuclear regions of several barred galaxies show intense CO emission arising from twin peaks, which are oriented perpendicular to the large-scale stellar bars and located where dust lanes intersect nuclear rings of HII regions. These twin gas concentrations can be explained by the crowding of gas streamlines near stellar inner Lindblad resonances. In the barred nuclear starburst galaxy NGC 3504, a large concentration of molecular gas is centered on the nucleus, apparently inside an inner Lindblad resonance. Star formation is consuming the gas most rapidly where the rotation curve is nearly solid body, suggesting that tidal shear helps control the rate of star formation. A comparison with M82 and NGC 1068 suggests that the starburst in NGC 3504 is in an early phase of its evolution, and that starburst evolution is strongly influenced by shear.
Molecular Gas Distribution and Dynamics in the Central Region of Galaxies
Authors: Ishizuki Sumio
Published: July 2016

To investigate the relation between a large-scale stellar bar and circumnuclear starburst, the CO (J=1→0) emission of circumnuclear regions of three starburst galaxies NGC2782, NGC3504, and M83 (NGC5236) have been mapped with the Nobeyama Millimeter Array. The high resolution CO (J=1→0) images indicate that the molecular gas in the three starburst galaxies is located interior to the innermost ends of the paired straight dust lanes. The molecular gas at the small radii is associated with their circumnuclear starburst sites which are indicated by radio continuum emission.
Interferometric Observations of HCO+ and HCN in the Nuclear Region of IC 342 and Maffei 2
Authors: Nguyen-Rieu  , Viallefond F. , Combes F. , Jackson J.M. , Lequeux J. , Radford S. , Truong-Bach
Published: July 2016

The IRAM interferometer has been used to image the distribution and kinematics of the HCO+ line in the nuclear region of IC 342 and of the HCN line in the nuclear region of Maffei2. Both regions were also imaged in the continuum at 3mm. These observations are compared with observations of HCN in IC 342 and CO in both galaxies.
Jet-Cloud Interactions in NGC 4258: CO Observations Using the Nobeyama Millimeter Array
Authors: Plante R. L. , Handa T. , Lo K. Y.
Published: July 2016

Recent CO studies of spiral galaxy NGC 4258 have revealed a close relationship between the molecular gas and the anomalous arms, recently interpreted as jets (Cecil et al. 1992, Martin et al. 1990). An IRAM single dish study by Krause et al. (1991) showed the CO to be concentrated around the Hα arms. Interferometrie imaging of the inner 1’ by Martin et al. (1990) showed the molecular gas confining the arms; they suggested that the jet had initially plowed a tunnel through the disk gas, producing a free path for subsequent ejections. This data also shows strong evidence for a jet-cloud collision along the N W arm (Piante et al. 1991).

To learn more about the jets, we are motivated to exploit the jet-gas relationship with multi-field imaging of the CO along the anomalous arms using the Nobeyama Millimeter Array. We present preliminary results from our first 60” field, centered on the SE Hα arm, 43.5” from the nucleus. Observations in the two most compact configurations (C and D) produced a 4” x 6” beam.
NGC 4631: The Unusual Star Forming Region Around CM67 — CO Observations with NMA and Pico Veleta
Authors: Krause M. , Golla G. , Morita K.-I. , Wielebinski R.
Published: July 2016

The late-type edge-on spiral galaxy NGC 4631 is known for its high star formation rate and extended radio halo with a uniform magnetic field component ordered predominantly perpendicular to the plane of the galaxy in the inner 6 kpc (assuming a distance of 7.5 Mpc, 1′ = 2.2 kpc) (Hummel et al. 1988; Golla, Ph.D., in preparation). The strongest radio continuum source of NGC 4631 is located at the eastern edge of the central region near a giant HII region complex CM67 (Crillon and Monnet 1969). The magnetic field orientation going out from the central region and especially from the region CM67 as well as the prominent north eastern low frequency radio spur (cf. Hummel et al. 1991) indicate a close connection between the synchrotron emission of the radio halo of NGC 4631 and star forming regions/CM67 in the disk (Golla and Hummel, in preparation). Probably cosmic rays from star forming regions in the disk propagate along the magnetic field Unes into the halo.
Tracing Molecular Emission in Spiral Galaxies: The Near Infrared Correspondence
Authors: Hurt R. L. , Turner J. L. , Levine D. , Merrill K. M. , Gatley I.
Published: July 2016

Near infrared imaging can be a powerful tool in tracing the densest molecular structures in galaxies. The observable molecular emission originates in large molecular cloud complexes which are also subject to significant extinctions caused by the associated dust. It can be difficult to distinguish between regions of moderate and large molecular density with optical observations as both will appear optically thick. Since extinction in the near infrared is only about a tenth of the corresponding visual extinction, multi-band near infrared imaging will trace the regions of the highest optical depths much more effectively. With the advent of large format infrared imaging arrays it is now possible to use infrared extinction maps as a probe of the large scale distribution of molecular emission in extragalactic sources.
Interacting Intersecting Masers
Authors: Deguchi Shuji
Published: July 2016

An interaction of two masers through plasma longitudinal waves in the Stimulate Raman Scattering has been investigated and applied for the extreme high-velocity (900 km s-1) water masers discovered in NGC 4258. For the stimulated Raman scattering, the frequency down-shifted components are easily created but not the up-shifted components. We use the interacting masers for the explanation for the presence of the up-shifted components. The interaction occurs when the wave vector of the longitudinal plasma wave associated with one incident maser coincides with the wave vector of the other longitudinal wave associated with the other maser. This interaction produces two daughter waves, frequency up-shifted and down-shifted radiations with a shift of roughly a plasma frequency. This interaction occurs when two masers intersect with intersecting angle of about 176 degree in plasma of the electron density of about 5 106 cm-3. The brightness temperature of the original incident masers must be greater than about 1013 K (depending on the line width, and the maser beaming angle, etc.) and the scale length of plasma must be larger than about 1013 cm.
Background-Limited Performance in the Submillimeter
Authors: Davidson J. A. , Roellig T. L. , Pernic R. J.
Published: July 2016

We have been awarded NASA funds to construct a Submillimeter (SMM) Array Photometer for use at the Caltech SMM Observatory (CSO) on Mauna Kea. The array will consist of 5×5 composite bolometers illuminated through light cones. On the CSO, each cone will cover 25 arcsecs on the sky, implying a total field-of-view for the array of just over 2×2 arcmins. Our aim is to achieve background-limited performance in the 730 and 870 μm atmospheric windows, thus obtaining a Noise Equivalent Flux Density (NEFD) of approximately 0.1 Jy/√Hz at these wavelengths. This sensitivity level will enable 5-sigma measurements of 10 mJy sources (such as radio-quiet quasars) in about one hour. We also will have the capability to operate at 1.1 mm, but the photometer will not be optimized at this wavelength. This system is expected to be operational on the CSO in January 1994.
RATAN-600 as a MM-Array
Authors: Parijskij Yu.N. , Pinchuk G.A. , Verkhodanov O.V. , Khaikin V.B. , Zverev Yu.K. , Zhekanis G.V.
Published: July 2016

It is shown that multi-elements surface of the Russian biggest reflector may be considered as a 1000-element array with limited freedom of motions of each element. This limitation may be compensated by selection of the proper “virtual sub-array” of elements at any given direction of observations. This approach is especially effective for mm-waves where field of view of 600-meter reflector in usual mode is less than 1 arcsec. The present stage of realization of that project is shortly discussed, including requirements for multi-feed system near the focal plane of the radio telescope, wavelength limitations and error budget, and near field zone 3-dimensional synthesis mode of observation.
The Millimeter Array
Authors: Brown Robert L.
Published: July 2016

The Millimeter Array, under development in the United States, is a fast and flexible telescope capable of imaging the thermal sky at a resolution equal to that specified in the design goals of the Hubble Space Telescope. The MMA is a project of the U.S. National Science Foundation, and it has been highlighted as one of the four major U.S. initiatives in astronomy for the decade of the 1990s. Construction will begin toward the end of the decade at a site soon to be chosen.
A Southern Hemisphere Millimetre Array
Authors: Booth R.S.
Published: July 2016

The southern night sky is a sight of overwhelming beauty. It is hard to forget one’s first view of the night sky from La Silla with the Galactic centre overhead and the brilliant constellations of Sagittarius and Scorpius with their bright stars and copious amounts of dust. In fact for a millimetre astronomer, it is the dust that is so striking and one feels for the first time that one is seeing tangible visual evidence of the intriguing molecular clouds that dominate our discipline.

Ironically it is the observation of these southern molecular clouds that have shaped much of millimetre radio astronomy, yet we persist in observing them from the northern hemisphere through many air masses of atmospheric attenuation.

Having built the Swedish ESO Submillimtre Telscope, SEST in the south, on La Silla, in Chile, Swedish and other European astronomers would like to follow up this initiative with a southern hemisphere millimetre array, taking advantage of the excellent dry mountain sites. There is much to be done with such an instrument.
Submillimeter Interferometry in Space
Authors: Brown Robert L.
Published: July 2016

Radiation from the gaseous disk of a galaxy like the Milky Way principally occurs via fine structure transitions of carbon, oxygen, and nitrogen, all of which occur at submillimeter wavelengths at which the earth’s atmosphere is opaque. Indeed, more than ten percent of all the energy radiated by the stars and gas in the Milky Way comes out in the 1900 GHz line of once ionized carbon! This line can only be observed from space, and it can only be observed with arcsecond angular resolution with a space-based interferometer. The international space station Freedom provides a stable platform, with the right dimension, for the necessary submillimeter interferometer.
Using HST/GHRS Echelle Spectra as Templates for IUE Data Analysis
Authors: Wahlgren Glenn M. , Leckrone David S. , Johansson Sveneric , Rosberg Maria
Published: July 2016

Echelle spectra obtained with the HST/GHRS are used to understand the blending in lower resolution IUE sprectra in the region of the raie ultime line of Au II. Laboratory analysis of the Au II transition has provided an accurate wavelength and transition probability from which the first Au abundances are determined for stars other than the Sun.
Comparison of Different Methods for Determining Atmospheric Parameters of A and F Stars
Authors: Smalley B. , Dworetsky M.M.
Published: July 2016

The atmospheric parameters of metallic-lined (Am) stars have been the subject of much debate. Using spectrophotometric flux fitting, Lane & Lester (1984) obtained values of Teff and log g for several classical Am stars that were systematically lower than those obtained by Dworetsky & Moon (1986), who used empirically calibrated uvbyß photometry. We have used the standard procedures of photometry, spectrophotometry and hydrogen-line profile fitting to determine the atmospheric parameters of many A and F stars, including several Am stars. Modifications to the standard techniques have been used to allow for the effects of cooler companion stars in the determination of such parameters. It is found that spectrophotometric methods give results for Teff and log g that are highly sensitive to the adopted metal abundance. This explains the anomalous results of Lane & Lester.
Line Variability in 33 Gem?
Authors: Hubrig Swetlana , Launhardt Rainer
Published: July 2016

The spectrum of 33 Gem exhibits a great similarity with that of a CP3 star, but in contrast to other members of this group, light variations and variability in helium lines were reported. Even an effective magnetic field strength up to 1.4 kG was measured in the lines of elements He I, Si n, P H, Mg II, Ti H, Mn II, Fe H (Glagolevskij et al., 1985). For these far-reaching differences high resolution (R≃ 40000), high signal-to-noise (> 100) CCD spectra of 33 Gem were observed with the Coudé spectrograph of 2.2 m telescope at Calar Alto. As well for the profiles of the He I lines as for those of the metallic lines no changes could be found. Our rough inspection of Zeeman spectograms taken with the 6 m telescope at Zelenschuk in which Glagolevskij et al. noticed a magnetic field revealed unexpected splitting of several lines into two components probably caused by a companion. The line components are separated approximately by 0.1 Å. For this splitting a confirmation of the presence of a magnetic field was difficult.
Hydrogen-Line Profiles of Some λ Bootis Stars
Authors: Iliev Ilian Kh. , Barzova Ina S.
Published: July 2016

The observed hydrogen-line profiles of four λ Boo type stars— HD 111786, HD 125162, HD 179791 and HD 192640 are presented. Existence of two separate groups based on the shape of these lines is confirmed. Radial velocity (Vr = −5 ± 3 kms−1) and projected rotational velocity (vsini = 130 ± 10 kms−1) for HD 111786 are measured.
Mechanisms of Separation of Elements
Authors: Michaud Georges , Proffitt C. R.
Published: July 2016

Since the last IAU Colloquium devoted to Ap stars, die continuous development of high signal to noise observations and of computerized analysis tools have greatly increased the effectiveness of abundance anomalies as a probe of hydrodynamical processes in stars. Until the 1980s, they seemed limited to ApBp and AmFm stars where the effects are largest. More recently the abundances of Li and He have been suggested to play important diagnostic roles for hydrodynamics in both the Sun (Proffitt and Michaud 1991b, Pinsonneault et al. 1989) and Halo stars (Proffitt and Michaud 1991a, Pinsonneault et al. 1992, Vauclair 1988, Charbonnel et al. 1992, Deliyannis and Demarque 1991). The observation of a Li abundance gap in F stars of clusters has raised the question of the link between these objects and the AmFm stars (Michaud 1986, Charbonneau and Michaud 1988, 1991) or alternately with solar type stars. The observed Li abundance on die subgiant branch sheds some light on this problem (Charbonneau et al. 1989; Charbonnel and Vauclair 1992). In solar type stars, the observed Li abundance constrains the superficial turbulence that may inhibit surface He gravitational settling (Proffitt and Michaud 1991b) whose effects can be detected using solar seismology (Guzik and Cox 1992, Dziembowski et al. 1992).
Diffusion: Theoretical Computations for Non-Magnetic Stars
Authors: Alecian G.
Published: July 2016

We present the main aspects of diffusion calculations in the simplest realistic diffusion model for main-sequence CP stars. The results obtained with this kind of computations are generally used in modelling AmFm and HgMn stars. Important improvements in this field, essentially due to the new atomic data banks, may be expected in the near future.
Non-LTE Analysis of CNO Lines in Vega
Authors: Takeda Yoichi
Published: July 2016

Non–LTE calculations for neutral C, N, and O are performed to determine the accurate abundances of these elements in the atmosphere of Vega by taking the non–LTE effects realistically into consideration. It is shown that C and O are mildly deficient by ∼0.2–0.3dex while N shows an appreciably large underabundance by ∼0.8dex.
CP Stars at High Galactic Latitude: Photometry Near the Galactic Poles ,
Authors: Schneider H.
Published: July 2016

The results of photometric observations of early type stars in regions around the Galactic poles are presented. The aim of these investigations was to search for CP2 and CP1 and to establish new and more precise frequencies for such objects including fainter stars.

A mean frequency of 24.7% was found for the CP1 stars, 23.7% for the hot CP2, and 11.7% for the cooler ones, but with large differences between the two regions investigated.

Furthermore, a substantial number of stars (20) were found to be good candidates for λ Boo stars.
Complications of Studies of Galactic Structure, Caused by Cp Stars
Authors: Lodén L.O. , Sundman A.
Published: July 2016

When studying the distribution of stars and interstellar matter in the galactic environment, one relies upon objects which are numerous enough and also bright enough to constitute workable samples. A-type stars seem to be a natural choice, but a successful study then depends on the reliability of the spectroscopic distance determinations. Since chemical peculiarity affects a considerable fraction of the A-type main sequence stars we have found reason to investigate the reliability of luminosity estimates for stars of various types of peculiarity. The result indicates that peculiarity is a less serious problem than undetected multiplicity.
Stellar Photospheres and Molecules — A View From The Bridge
Authors: Lambert David L.
Published: July 2016

The allegory alluded to in the subtitle of my review came to mind in the early morning hours when I was battling insomnia after a successful observing run at our McDonald Observatory. Similar bouts with insomnia are more widely classified as “jetlag,” a condition probably too familiar to many of the readers!

Imagine two villages connected by a bridge spanning a deep, fast-flowing river. In my village on the south bank live the astronomers. Across the bridge live the chemical physicists and the physical chemists who are engaged in determining by all possible theoretical and experimental means the structure and spectra of molecules (and atoms). The astronomical community can be sorted into various clans of whom I consider here only the stellar spectroscopists and, in particular, the small subclan fascinated by quantitative spectroscopy who to pursue their trade must establish and maintain excellent communications with the village on the other side of the bridge. The necessity for contacts between the two villages has grown with the development of the tools of the stellar spectroscopists’ trade: e.g., the advances of telescopes and spectrographs with respect to coverage of the electromagnetic spectrum and sensitivity, and the theoretical developments in the construction of model stellar atmospheres and the computation of synthetic stellar spectra. The recent decades of astronomical advances have been matched by exciting years in the village across the bridge: e.g., tunable lasers have spawned a renaissance in molecular (and atomic) spectroscopy, and theoretical work on molecular structure and spectra has advanced with the awesome growth of computers. Yet, a curious paradox may be sketched. These welcome and remarkable developments in the two villages have made it more difficult to maintain effective communications across the bridge. How can I possibly exploit fully the successes of MRD-CI calculations and appreciate their limitations? My counterparts across the bridge will echo my question: What experiments or quantum calculations might be usefully made in support of the astronomers’ programs ATLAS, MARCS, SOSMARCS, and their relatives?
Astrophysical Applications of Approximate Methods for Molecular Opacities - from stars to substellar brown dwarfs
Authors: Tsuji Takashi
Published: July 2016

For studies of radiative processes in stellar environment, knowledges on opacities are essential, and molecular line opacities play a dominant role in many cases where temperatures are roughly below 4,000K. Accurate treatments of molecular line opacities require high precision line data for millions (and up to billions?) of lines. Recent progress in theoretical as well as in experimantal molecular physics made it possible to realize such an approach, and dedicated efforts are being done to developing extensive databases for polyatomic (Jørgensen in this volume) as well as for diatomic (Kurucz in this volume) molecules. These accurate databases should be of fundamental importance in our understanding of astronomical observations that are progressing rapidly both in scope and in accuracy.
From Molecules to Grains
Authors: Sedlmayr Erwin
Published: July 2016

Cosmic dust is an ubiquiteous component of the interstellar medium, the presence of which has severe bearings both upon the observations and upon the physical description and realistic modelling of astronomical objects. In most dusty objects, the grain component is intimately interwoven with the gas component and the radiation field, and, hence strongly affects the thermodynamical, the hydrodynamical and the chemical structure of the object. Therefore any consistent description of the astrophysical dust complex has to rely upon a treatment where these aspects are properly taken into account. In general this complex comprises the following problems:

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Formation of small stable molecular clusters out of the gaseous phase

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Growth of these clusters to macroscopic specimens (primary condensates: grains, plates, etc.)

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Destruction of grains (e.g. thermal evaporation, sputtering, shattering), and

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Physical and chemical processing of already existing grains (e.g. coagulation, chemical and thermal transformation, etc....).
Pressure-Induced Molecular Absorption in Stellar Atmospheres
Authors: Borysow Aleksandra
Published: July 2016

Pressure-induced absorption arises in complexes of two or more inert atoms or molecules, due to dipole moments induced during the collisional interaction. The term “pressure-induced” still prevails in the astrophysical literature, yet “collision-induced” absorption (CIA), or “interaction-induced” absorption seems more appropriate and is commonly used elsewhere. Ordinary absorption processes in the infrared arise from individual, polar molecules interacting with electromagnetic radiation. As a consequence, the intensity of the allowed lines increases linearly with density. CIA, on the other hand, is most striking in gases composed of nonpolar, infrared-inactive molecules. Induced spectral lines are observed at rovibrational frequencies which are dipole-forbidden in single (i.e. non-interacting) molecules. Dipole transitions may, however, beinducedin the interacting pair. The new symmetry of the electronic cloud of a collisional complex may be very different from those of the isolated molecules and thus commonly allows for a transient dipole, which then interacts with radiation. Collision-induced absorption increases quadratically in the low density limit, thus reflecting the two-body origin of the basic absorption process. At higher gas densities, ternary interactions become significant and cubic and higher-order contributions to the observable absorption are then commonly seen.
Computation of the Absorption Coefficient for Diatomic Molecules
Authors: Larsson Mats
Published: July 2016

Molecules in stellar atmospheres play key roles, not only as promoters of our understanding of stars, but also as actors affecting the structures of the atmospheres. In particular cool star atmospheres are affected by molecular opacities, and during recent years it has become clear that also weak molecular lines are of crucial structural importance. Extensive molecular data are thus needed in order to correctly model the structure of a stellar atmosphere and the transport of radiation through it. The basis for how such molecular data are acquired constitutes the theme of the present article. As will follow below, results from different subfields of molecular physics are needed in order to obtain a complete picture of the absorption of radiation by molecules. This article will only consider allowed molecular electronic transitions, i.e. dipole transitions betweendifferentelectronic states; however, the presentation and the formulae may easily be modified to be valid for transitions between levels within a single electronic state.
Laboratory Millimeter Wave Spectroscopy of Small Reactive Species
Authors: Demuynck C. , Bogey M. , Bolvin H. , Cordonnier M. , Destombes J.L. , Walters A.
Published: July 2016

The discovery of a large variety of molecules by radio astronomy has been a very strong motivation for the development of laboratory millimeter wave spectroscopy. Among them, the reactive species, neutral and/or ionic, have been early recognized as playing a very important role in the chemistry of the interstellar and circumstellar medium. While the laboratory spectroscopy of free radicals started relatively early, with the observation of the OH radical by the group of Townes (Dousmanis et al. 1955), the detection of molecular ions proved to be a much more difficult task, and the first millimeter line due to an ion was actually detected by radio astronomy (Buhl & Snyder 1970). It was called “U89.2” until it was tentatively attributed to HCO+by Klemperer (1970) on the basis of both considerations on the chemistry of the interstellar medium, and of ab initio calculations for the prediction of the expected line frequency. This identification was later confirmed by more elaborated ab initio calculations (Wahlgren et al. 1973, Kraemers & Diercksen 1976), and by the observation of a transition attributed to H13CO+(Snyder et al. 1976), but the definite confirmation was the observation of the same transition in a laboratory glow discharge by the group of Woods (Woods et al. 1975).
The Bosscha Observatory Schmidt Telescope
Authors: Dien Elsa van Albada-van
Published: July 2016

A brief history is presented of the Bosscha Observatory in the 1950s, when the plans for a Schmidt telescope in Lembang materialized.
CCD Cameras for the Kiso 105 cm Schmidt Telescope
Authors: Yoshida S. , Aoki T. , Soyano T. , Tarusawa K. , Sekiguchi M. , Doi M. , Kashikawa N. , Okamura S. , Shimasaku K. , Yagi M. , Yasuda N.
Published: July 2016

We report on the status of the CCD cameras for the Kiso 105-cm Schmidt telescope. We have two types of cameras – single-chip and mosaic. The single-chip camera is available for common use. At present about 90 % of the telescope time is allocated to observations with CCD cameras.
Near-Infrared Imaging with the 105 cm Kiso Schmidt
Authors: Ichikawa T. , Tarusawa K. , Yanagisawa K. , Itoh N.
Published: July 2016

We have carried out imaging observations in the near-infrared (J, H and K’ band) with a large format array camera attached to the prime focus of the 105 cm Schmidt telescope at Kiso Observatory. The image resolution, limiting magnitudes and effect of thermal radiation are presented, based on observations of nearby galaxies. Considering the results, we are constructing a new larger near-infrared camera optimized for use with the Kiso Schmidt.
T A U M O K—Multi-Object Spectroscopy with the Tautenburg Schmidt Telescope
Authors: Marx S. , Lehmann H. , Pluto M. , Ziener R.
Published: July 2016

A multi-object camera for the Tautenburg Schmidt Telescope (134/200/400) was developed and constructed in cooperation with the Max-Planck-Institut für Astronomie in Heidelberg and the Thüringer Landesstemwarte Tautenburg. The experience with the “Spaltspinne” for the 3.5 m Telescope of the Calar Alto Observatory (Pitz 1993) was the foundation of TAUMOK. The technical concept was given by Pitz et al. (1993).

Thirty six rods controlled by a processor can be moved in an area with a diameter of 16 cm. This area covers a field of 2.3° in the focal plane which is flattened by a plano-convex lens. Each of 34 rods carry two fibres with diameters of 100/µm with one fibre for the object and another for the background light. The fibres have a length of 7 m and their opposite faces form the entrance slit of a spectrograph. At present, reciprocal dispersions of 3.4, 10, 20 and 40 nm/mm can be realized. A CCD camera with a chip-size of 1152 × 770 pixels (pixel size 22.5/µm) is used as detector. Two of the 36 rods are equipped with image bundles for telescope guiding.
The Latest Results from the Durham/UKST Galaxy Redshift Survey
Authors: Broadbent A. , Shanks T. , Fong R. , Parker Q. A. , Watson F. G.
Published: July 2016

We report on a redshift survey of ∼ 4000 galaxies of B ≲ covering a 1500 square degree area of sky around the SGP region. This 1-in-3 sampled survey probes a contiguous volume of 4 × 106 Mpc3 to a depth of 300 h−1 Mpc. The survey has been compiled using the fibrelinked spectroscopy system, FLAIR, on the UK Schmidt Telescope and has produced high quality redshift maps giving a clear visual picture of structure in the universe as well as providing an excellent data base for a statistical analysis of galaxy clustering. Filamentary and sheet-like features are clearly discernible to the eye in the completed sections of the survey although the redshift two-point correlation function is consistent with zero on scales of r ≳ 10h−1 Mpc. The survey, which is now substantially complete, demonstrates the potential of the FLAIR spectroscopy system for extending this project to a medium-deep galaxy redshift survey of the whole of the southern sky on timescales which would remain competitive with other surveys under construction.
Digitisation, Archiving, and Distribution of Photographic Data from Schmidt Surveys
Authors: Lasker Barry M.
Published: July 2016

The limititations to the use of data from the major Schmidt surveys, i.e. grain noise as well as practical considerations of image processing and astrometry, are discussed, together with the question of mounting films on microdensitometer platens. Next, the major scanning systems dedicated to Schmidt surveys, their accomplishments, and their future programs are considered. Finally, the archiving and distribution of the scan data is discussed, and some suggestions regarding future directions are made.
A Deep Wide Field Survey from Digitally Stacked Schmidt Plates
Authors: Hawkins M. R. S.
Published: July 2016

A large set of exposures of a single UK Schmidt Telescope field has been obtained, covering five colour bands over 18 years. Techniques have been developed for combining digitised data from many plates. The results of adding 64 exposures in Bj and R are demonstrated showing that the expected gain of ~ 2.5 magnitudes in limiting magnitude are achieved. By combining various subsets of the data, proper motions and variability can be determined. Two examples of the many possible uses of the dataset are given: the discovery of low mass brown dwarf candidates using colours and proper motions, and of quasars using variability and colours.
Objective-Prism Spectroscopy: Retrospective and Prospective
Authors: MacConnell D. Jack
Published: July 2016

The combination of the excellent large-field imaging capabilities of Schmidt telescopes and of prisms covering the full aperture has made an impact on stellar, galactic, and extragalactic astronomy far out of proportion to the numbers of such telescopes. I discuss some of the milestones in the continuing development of this combination with a view to signposts of the future.