bluuebunny/crossref_metadata_2025 huggingface dataset:
The Non-Explosive Modes of Hydrogen Burning: A Brief Review
Authors: Arnould Marcel , Mowlavi Nami
Published: July 2016

The present status of our theoretical and experimental knowledge of the rates of hydrogen-burning reactions in hydrostatic stellar conditions is very briefly reviewed. Special emphasis is put on reactions of the proton-proton chain, CNO cycles, NeNa cycle and MgAl chain whose rates are still affected by uncertainties that can have an impact on predictions regarding astrophysical issues of interest. This concerns in particular the solar neutrino problem, or the nucleosynthesis accompanying the CNO, NeNa and MgAl chains of reactions, as it is revealed in particular by the first dredge-up episode. A brief discussion of the possibility of reducing the present rate uncertainties is presented.
The Pre - Main Sequence
Authors: D’Antona Francesca
Published: July 2016

The Pre-Main-Sequence (pre-MS) is defined as the phase following the protostellar stage and ending with the ignition of hydrogen in the stellar core. Models in hydrostatic and thermal equilibrium such as typical “Hayashi track” models are basically adequate to describe the internal structure of pre-MS stars, although for a fraction of pre-MS objects there can be phases of accretion also at late stages, which may influence the surface abundances of light elements.

The interior evolution of pre-MS structures is focused in the two main stages’ of Deuterium and Lithium burning for the low mass (M ≤ 1.5M⊙) stars. The location in the HR diagram of theoretical tracks is still subject to large uncertainty, even more apparent today that new opacities and treatment of turbulent convection are available, and the results can be internally compared. Uncertainties amount to a factor ~ two for mass and age determination of individual objects, and affect the absolute location for both the D-burning and the Li-burning regions. Qualitative constraints, such as that there can not be Li-depletion at L ≥ L⊙, remain valid. Abundances of7Li at the surface of pre-MS stars, if measured at a stage which can definitely be considered previous to the possible occurrence of nuclear burning, and, consequently, previous to other depletion mechanism which may occur later on, provide constraints on galactic evolution of this element of cosmological interest.
New Physics, New Evolutionary Tracks, New Isochrones
Authors: Demarque P. , Guenther D.B. , Pinsonneault M.H.
Published: July 2016

Work has begun on the construction of a grid of theoretical isochrones based on important recent refinements in stellar physics. These refinements have already been applied to the construction of a standard solar model, which, for the first time, free of any adhoc assumptions, reproduces the observed p-mode oscillation spectrum within the errors of the physics (Guenther et al. 1992).
Main Sequence Structures Including The Overadiabatic CM Convection Model
Authors: Mazzitelli Italo , D’Antona Francesca
Published: July 2016

We computed the main sequence structure of masses from 2 to 0.7 M⊙ for two choices of helium (Y) and metal (Z) mass fractions. Models are given for solar composition (Y=0.285, Z=0.018) and for a composition appropriate to a younger population I (Y=0.32, Z=0.03). We took particular care both in the choice of the most recent opacities presently available and in the treatment of the input physics and numerics (see also D’Antona et al, 1992).

Opacities from Rogers and Iglesias (1992) were adopted where available, complemented with those by Kurucz (1991) at T≤10000 K and, elsewhere, by the Los Alamos opacities (Huebner et al. 1977). The equation of state by Mihalas et al. (1988) was used at ρ ≤ 0.01, and elsewhere the relation P = P(ρ,T) was taken from Magni and Mazzitelli (1979), while the adiabatic gradient was obtained from a Saha type e.o.s..
Determination of Age and Original Chemical Composition of Binary Stars
Authors: Ferluga S. , Antillon M.
Published: July 2016

A numerical method is presented, which is able to determine quantitatively the age t and the initial abundances of helium and metals (Y0, Z0) of a given binary system. Input data are simply the values of mass m, temperature Teff and surface gravity g, of both stars. The procedure works for detached main-sequence binaries, and it does not require any preliminary hypothesis about surface abundances or age. It is assumed that the two stars evolve parallely with no interaction.
Modelling The ζ Herculis System
Authors: Lebreton Y. , Auvergne M. , Morel P.J. , Baglin A.
Published: July 2016

The ζ Herculis system is one of the closest well-kown binaries. A tentative modelling shows that though the brighter star is easily described with a mass compatible with the observed one and an age of approximately 3.4 billion years, difficulties arise for the secondary, which plea for more precise observations.
The Blue Straggler Stars of Galactic Clusters
Authors: SchÖNberner D. , Napiwotzki R.
Published: July 2016

The origin and evolution of blue straggler stars (BS) in clusters is still an unsolved problem for our understanding of stellar evolution. Several rivalling theories exist, of which that of Saio & Wheeler (1980) is the most interesting one since it assumes additional mixing of fuel in the interior of BS. This theory predicts larger luminosity-to-mass ratios for a given position in the HR diagram compared to the standard evolution theory. This theory has been taylored for the old galactic cluster NGC 7789 which contains many bona fide BS, but it can also be used for other clusters of similar ages. The other theories rely on the standard theory of stellar evolution and assume (1) binary mass exchange or even merging, or (2) delayed star formation. In either case follows a “normal” luminosity-to-mass ratio. We report here on a careful spectroscopic investigation in order to discrimate between these rivalling theories.
Pulsation of Rotating and Magnetic Stars
Authors: Vorontsov Sergei V.
Published: July 2016

Rotation and a magnetic field break the spherical symmetry of a star viewed as a pulsating system, lifting the degeneracy of oscillation frequencies, and leading to (sometimes prominent) observational consequences. Theoretical studies of rotational and magnetic effects in pulsating stars are reviewed, starting with simple configurations with slow rotation and weak magnetic fields.
The Asteroseismic Calibration of Solar-Type Stars
Authors: Gough D.O. , Novotny E.
Published: July 2016

The addition of seismic parameters to stellar-model calibrations substantially increases the constraints one can place on the properties of stars. We present some preliminary calculations to assess the accuracy with which certain stellar parameters can be inferred. For simplicity we use just two of the three most basic seismic parameters characterizing the low-degree p modes that might be measured from intensity variations by instruments such as photometers planned for the ESA spacecraft PRISMA. We ascertain the accuracy of a calibration of an isolated star and of a cluster of N solar-type stars.
Activity Tracers
Authors: Strassmeier Klaus G.
Published: July 2016

The vast variety of solar-like phenomena on other late-type stars, so-called activity tracers, provide an important tool for studying the structure of active stellar atmospheres and their connection to the stellar interior via strong magnetic fields. These “chromospherically active” stars include single and binary stars as well as pre- and post-main sequence objects and have rapid rotation and deep convective layers in common. They serve as astrophysical laboratories to study the vast phenomenology of activity tracers: starspots, plages, flares, prominences, which might be seen as enhanced analogs of solar activity and could be spatially resolved due to rotationally modulated indicators. In this paper we review the current observational material and discuss its impact on our knowledge of “active” atmospheres, especially in the context of stellar rotation.
Photospheric Activity among Early F-Type Stars
Authors: Mantegazza L. , Poretti E. , Antonello E. , Zerbi F.
Published: July 2016

In the last decade stars showing variability of unclear origin have been detected among early F-type stars mainly as secondary results in the context of observational programmes devoted to the study of δ-Scuti and CP stars.

For this reason only a small number of these objects has been thoroughly studied: their positions in HR diagram is shown in fig.l.

Figure 1: HR diagram of the observed stars.

The stars in NGC 2516 have been singled out in a survey work by Antonello and Mantegazza (1986), HD 164615 has been studied by Abt et al.(1983), the variability in 9 Aur has been discovered by Krischinas et al.(1990,1991) and HD 23375 in Pleiades has been pointed out by Breger (1972). The solid line in Fig. 1 is the ZAMS and the dashed lines are the borders of the i-Scuti stars instability strip.
Results from Iphir as Guideline for Asteroseismology
Authors: Toutain Thierry , Fröhlich Claus
Published: July 2016

The long uninterrupted observation of the Sun as a star with the IPHIR experiment can be used to set limits to the significance of the determination of p-mode parameters as a function of time and the length of the time series of measurements.
β Cas: Simultaneous Stromgren Photometry
Authors: Rodriguez E. , Rolland A. , De Coca P. Lopez , Garrido R. , Gonzalez-Bedolla S.F.
Published: July 2016

The observations were carried out in August, 1983 using the 75 cm telescope at Sierra Nevada Observatory in Spain. This telescope is equipped with a six-channel uvbyβ photometer for simultaneous measurements in uvby and the narrow and wide Hβ channels, respectively. The observations were collected during four nights in the four uvby filters and one more night was devoted to measuring β Cas in the n and w bands of the Hβ Crawford system. In all cases, a calibrated neutral filter was used for β Cas. The comparison star was Cl=HR 9085 (V=5.m55, F0III).

The analysis of frequencies was carried out using the Discrete Fourier Transform method, as described in López de Coca et al. (1984), to the observational uvby points collected. The periodograms showed a principal peak at v=9.91 cd−l. After prewhitening for this frequency, the resulting periodograms did not show any trace of another peak, suggesting the monoperiodic nature of this star, in agreement with Antonello et al. (1986). Under the assumption of monoperiodicity of β Cas, the classical O-C method can easily be applied. Nine times of maxima were obtained for the four nights by using the method described in Rodriguez et al. (1990), where each light maximum has been derived as an average over the four uvby bands. When the O-C method was applied, the least squares fit converged to a linear ephemeris with the following elements: To=2445568.d5097 (±0.d0007) and Po=0.d10091 (±0.d00002). This linear ephemeris satisfactorily reproduces our data of β Cas.
Methodological Aspects in the Frequency Analysis of Multiperiodic δ Scuti Stars
Authors: Mantegazza L. , Poretti E. , Antonello E. , Riboni E.
Published: July 2016

At Merate Observatory the study of δ Sct stars began in the sixties and spectroscopie and photometric campaigns were continuously undertaken in order to clarify the controversial points. As an obvious extension of the research, the observation of δ Sct stars was proposed for telescope-time allocation at European Southern Observatory, in order to take advantage of the ESO facilities and of the considerably better sky of La Silla. We put in our observing programme δ Sct stars showing cycle-to-cycle variations and, possibly, an amplitude larger than 0.05 mag in order to have a better signal-to-noise ratio; they are listed in the table. It is important to notice that we always tried to collect a number of measurements as large as possible (from 1988 we collected more than 1000 measurements per star), because it is a well-established fact that periodicities with

an amplitude of a few thousandths of magnitude can be present in δ Sct stars. Moreover, when several modes are excited, an adequate frequency resolution becomes necessary and, therefore, a sufficient time baseline is requested (Poretti and Mantegazza 1992). A poor data sampling also gives an apparent good fitting for several solutions, all leaving a small residual rms, and there is no possibility to choose among them: different authors can pick up different solutions, generating the conflicting interpretations often found in δ Sct star literature.
Asteroseismology of the DBV White Dwarf GD 358 with the Whole Earth Telescope
Authors: Winget D.E. , Nather R.E. , Clemens J.C. , Provencal J. , Kleinman S.J. , Bradley P.A. , Claver C.F. , Dixson J.S. , Wood M.A. , Grauer A.D. , Hine B.P. , Hansen C.J. , Bergeron P. , Birch P. , Candy M. , Leibowitz E. , Marar T.M.K. , Seetha S. , Ashoka B.N. , O’Donoghue D. , Warner B. , Buckleys D.A. , Tripe P. , Vauclair G. , Doleza N. , Chevreton M. , Kanaan A. , Kepler S.O. , Augusteijn T.
Published: July 2016

We report the analysis of 154 hours of nearly continuous high-speed photometric data on the pulsating DB white dwarf (DBV) GD 358 obtained during the Whole Earth Telescope (WET) run of May 1990. The Fourier transform (FT) of the light curve is dominated by power in the range from 1200 – 1700μHz with more than 180 significant peaks in the total transform. We also see significant power at the sums and differences of the dominant frequencies, indicating the importance of nonlinear behavior. We can use this data to obtain an accurate total stellar mass, and surface He layer mass. The implied surface He layer mass, if correct, provides a significant and surprising challenge to stellar evolution theory, as well as the theory of chemical mixing.
Star Formation and the Origin of Stellar Masses
Authors: Podsiadlowski Ph. , Price N.M.
Published: July 2016

We present a new model to explain stellar mass distributions in different stellar environments. In our model, the protostar phase is terminated, when the protostellar core embedded in a molecular clump experiences a collision with another star or protostellar clump, which ejects the protostellar core from its parent clump. Such dynamical interactions are necessarily important, if stars preferentially form in dense clusters. We show that, in a simple model, the initial mass function approaches a simple, asymptotic form, which strongly resembles observed mass functions. The model has important consequences for star formation in different environments. We also discuss the implications of the model for our understanding of pre-main-sequence stellar evolution.
The Effect of Electron Beams on the Hydrogen Emission in Impulsive Flares on the Sun and Stars
Authors: Zharkova V.V. , Kobylinsky V.A.
Published: July 2016

Flares are very frequent phenomena on the sun and on other stars and are actively investigated with precise observational techniques. These studies are particularly stimulated by recent X-ray and UV observations on spacecraft (Skylab, SMM). From all these observations the flares on the sun and stars seem to be of the same physical nature but of different energetic power. A number of investigations devoted to comparison between the solar and stellar flares led to the conclusion that they have the similar mechanisms for the energy release and transport and for their manifestations in different ranges of electromagnetic radiation.

The hydrogen emission is easy to observe in these events, and thus it is convenient for diagnostic analysis of physical conditions in the flares. However, the impulsive events were considered to be observed in X-rays so only. Zharkova & Kobylinsky (1992, 1993) have recently shown that the hydrogen continuous radiation of the solar flares is sensitive to the electron beam parameters. We also develop an approach to detection of the flares of non-thermal or thermal origin by observing the hydrogen Balmer and Pashen continuum emissions with high temporal resolution.
The Naming of Stars and the Study of Protostars
Authors: Morrison D.R.O.
Published: July 2016

The logic of naming stars could be based more on physical principles as happened in the naming of resonances in Particle Physics. A possible system might be based on extensive Monte Carlo studies of protostars followed by standard Stellar Evolutionary Model calculations.
Prisma: A New Space Mission For Stellar Physics
Authors: Appourchaux T. , Gough D. , Hyoyng P. , Catala C. , Frandsen S. , Fröhlich C. , Jones A. , Lemaire P. , Tondello G. , Weiss W.W.
Published: July 2016

PRISMA (Probing Rotation and Interior of Stars: Microvariability and Activity) is a new space mission of the European Space Agency. PRISMA is currently in a Phase A study with 3 other competitors. PRISMA is the only ESA-only mission amongst those four and only one mission will be selected in Spring 1993 to become a real space mission.

The goal of the Phase A study is to determine whether the payload of PRISMA can be accommodated on a second unit of the X-ray Multi-Mirror (XMM) bus; and whether the budget of the PRISMA mission can be kept below 265 MAU (’88 Economic conditions). The XMM mission is an approved cornerstone and is in a Phase A together with PRISMA.
A New Violent Activity in 3C273
Authors: Botti L.C.L.
Published: July 2016

In the present paper we report a sharp rise in the flux density of the quasar 3C273 observed with the Itapetinga radiotelescope in 1991. The intensity increased by factor 2, reaching a maximum value in May and July 1991 at 43 and 22 GHz, respectively.
Millimeter-Wave VLBI Observations of Compact Steep-Spectrum Radio Sources
Authors: Kameno S. , Inoue M. , Takaba H. , Iwata T. , Takahashi Y. , Nan R. , Schilizzi R. T.
Published: July 2016

We report the observations of compact steep-spectrum radio sources (CSSs) by VLBI at 22 and 43 GHz and single dich at 22, 43, and 92 GHz. Our results show that CSS also has an active core as well as other AGNs.
Atmospheric Effects and Calibrations
Authors: Masson Colin R.
Published: July 2016

Atmospheric opacity severely attenuates millimeter and submillimeter signals. Fluctuations in refractive index limit the angular resolution of interferometers. Conventional phase calibration does not remove atmospheric phase fluctuations, but new techniques may.
New Applications of Radio Holography for MM Observations with the RATAN-600 Radio Telescope
Authors: Khaikin Vladimir
Published: July 2016

In the paper we describe the results of active holography RATAN-600 surface testing including the measurements of a single element profile and topography. The RATAN-600 beam pattern at 3.2 mm after an antenna correction and its dynamics during daytime are presented.
Imaging Molecular Envelopes of Evolved Stars
Authors: Bieging John H.
Published: July 2016

Resolved images of molecular emission lines from the envelopes of cool evolved stars reveal much about the physical processes by which such stars lose mass, about the chemical processes which occur in the outflowing gas, and about the evolution of the star to the planetary nebula stage. This paper reviews observational work on molecular line imaging at mm-wavelengths of carbon stars, Miras, proto-planetary nebulae, and planetary nebulae. The impact of these observations on our understanding of the late stages of stellar evolution as it affects the circumstellar environment is emphasized.
Gas Feeding Toward the Galactic Center
Authors: Ho P. T. P.
Published: July 2016

The previous two talks in this session have shown the importance of the nucleus of the Milky Way as the host to a possible massive black hole. SgrA* is apparently surrounded by a circumnuclear ring first seen in the HCN J = l-0 emission (Gusten et al. 1987). Infall from the circumnuclear ring could explain the ionized streamers which appear to orbit SgrA* (Lo and Claussen 1983; Serabyn and Lacy 1985). Recent studies in the NH3 emission using the Nobeyama Millimeter Array (Okumura et al. 1989; 1991) and the Very Large Array (Ho et al. 1991) have suggested that a streamer may feed the Galactic center from the southern cloud M-0.13-0.08. Here we show a second streamer originating from the eastern cloud M-0.02-0.07 as well. In both cases, interactions between the molecular clouds and supernovae seem to be important, and can be seen in position-velocity diagrams. This may be the mechanism by which gas is pushed toward the central gravitational field.
Detection of Magnetohydrodynamic Shocks in the L1551 Outflow
Authors: Barsony M. , Scoville N. Z. , Chandler C. J.
Published: July 2016

We report the results of CO J=l—+0 mapping of portions of the blue outflow lobe of L1551 with ~ 7” (N-S) × 4” (E-W) resolution, obtained with the 3-element OVRO millimeter array. Comparison of our interferometer mosaic with lower resolution single-dish data shows that we resolve the strongest single-dish emission regions into filamentary structures, such as are characteristic of shock fronts mapped via their near-infrared H2 emission in other outflow sources.
Evidence for Protostellar Collapse in B335
Authors: Zhou S. , Evans N. J. , Kömpe C. , Walmsley C. M.
Published: July 2016

We summarize the evidence for protostellar collapse in B335.
THE CO(J=2-1)/CO(J=1-0) Luminosity Ratio in the Orion Giant Molecular Clouds
Authors: Sakamoto Seiichi , Hasegawa Tetsuo , Hayashi Masahiko , Handa Toshihiro , Oka Tomoharu
Published: July 2016

The first results of large-area mapping observations of nearby giant molecular clouds in the CO(J=2-1) emission are presented. The CO(J=2-1)/CO(J=1-0) luminosity ratio is 0.75 and 0.62 for the Orion A and B clouds, respectively. These values are consistent with those observed typically in disks of galaxies (−0.6), and are significantly lower than large values (≳1) often observed in active star-forming regions in galaxies. Active star-forming regions in galaxies cannot be explained by ensemble of Orion-like GMCs; they may contain a different population of molecular clouds with high J-2-1/J=1-0 luminosity ratio.
Large Scale Structure and Kinematics of the Orion Ridge
Authors: Wiseman J. J. , Ho P. T. P.
Published: July 2016

Clumps and filamentary structures have previously been observed in the extended molecular ridge of OMC-1 (see below). The region is affected by multiple outflow components, shock emission that extends 0.5 pc from the BN/KL core, and a foreground HII region expanding into the cloud. The region also displays a complex kinematical character, with a large scale shift in radial velocity along the ridge, multiple cloud velocity components (Womack et al. 1993), and fast gradients across constituent cores (Harris et al. 1983, Wiseman and Ho 1993).

To clarify the structure and kinematics of the region, we have used the VLA to observe with high (0.3 km s−1) velocity resolution and high (8”) angular resolution the NH3 (1,1) and (2,2) rotation-inversion lines over 20 adjacent fields covering a 3’ by 8’ region encompassing the KL region.
Expanding Hemisphere in Orion-KL Hot Core — CS(2–1) Observation with NMA —
Authors: Murata Y. , Kawabe R. , Ishiguro M. , Morita K.-I. , Hasegawa T. , Hayashi M.
Published: July 2016

We have made aperture synthesis observations of CS(2-1) emission using the Nobeyama Millimeter Array (NMA), and obtained ~ 2” × 3” (0.005 × 0.008 pc) resolution image to investigate the velocity structures of Orion-KL. We found not only well-known expanding doughnut but the expanding hemisphere in the Orion-KL hot core.
SiO (J=2-1) Observations of W49A with NMA: Evidence of Infall Motion toward Massive Core
Authors: Miyawaki Ryosuke , Hayashi Masahiko , Hasegawa Tetsuo
Published: July 2016

We observed W49A with NMA. We found rotational infall motion toward massive core. The rotational velocity and the infall velocity are 2±1 km s−1 /pc and 5±2 km s−1, respectively.
An Interferometric Observation of the NGC 7538 Molecular Cloud Core
Authors: Kameya Osamu , Kawabe Ryohei , Morita Koh-Ichiro , Ishiguro Masato , Hirano Naomi
Published: July 2016

A high-spatial-resolution observation of the NGC 7538 molecular cloud core has been performed with the Nobeyama Millimeter Array. We report on the detailed structure of the region including IRS1-3 complex and IRS11 based on the CS J = 1−0 line observational results.

The observation was done in December, 1988. The field center was at R.A. (1950)=23h11m36.8s, Dec (1950)=61° 11′ 10″ which is between IRS1-3 complex and IRS11. The primary beam, 2.5’(FWHM), was large enough to cover both IRS1-3 complex and IRS11. We used 18 baselines, and the synthesized beam became 10.6″×10.4″ (natural weight).
Small-Scale Structure of the Mon R2 Cloud Core
Authors: Henning TH. , Chini R. , Pfau W.
Published: July 2016

High-resolution mm continuum observations are especially well suited to detect clumpy structures in molecular clouds. In this paper we concentrate on the Mon R2 cloud core which is associated with a cluster of IR sources. Walker et al. (1990) made a 1.3 mm map with 30″ resolution. They found an unresolved and elongated structure extending from NE to SW. Here, we discuss high-resolution continuum maps at 870 and 1300 µm showing a rich clumpy structure on the scale of several 10 arcsec. The clumps are probably intimately linked to the star formation process in Mon R2.
Preliminary Results on the Molecular Emission from the T Tauri Circumstellar Disk
Authors: Van Langevelde Huib Jan , Van Dishoeck Ewine F. , Blake Geoffrey A.
Published: July 2016

We report the initial results of a study of the chemical composition of the T Tauri circumstellar disk. The excitation and distribution of CS and HCO+ are discussed. These two molecules behave quite differently in the YSO environment.
IRAS Galaxies
Authors: Scoville N.
Published: July 2016

Approximately thirty of the luminous infrared galaxies highlighted by the IRAS survey have now been mapped at high resolution using the millimeter arrays. In virtually all cases, extremely high gas concentrations are found in their nuclei (≤2 kpc) and in several cases, the gas mass fraction is extremely high (25-100%). Optical and near infrared imaging of the most luminous infrared galaxies shows significant distortions, double nuclei, and/or tidal tails indicating that these galaxies have probably undergone a recent galactic interaction. The dense molecular gas probably plays a pivotal role in the evolution of such dynamically disturbed systems: being dissipative the gas readily sinks to the central regions where it may fuel a nuclear starburst and possibly build up and fuel a central active galactic nucleus. In this picture, the IRAS galaxies may be crudely characterized by three parameters: the initial mass of ISM in the progenitor galaxies, the time since the interaction, and the fraction of the total luminosity attributed to young stars versus an active nucleus. In this scenario, systems such as the antennae (NGC 4038/39) may represent the early stages of a merger before the gas has been deposited in the nucleus; Arp 220 the phase in which a large nuclear gas concentration is presently fueling a starburst/AGN, and NGC 1068 the later phase in which much of the central gas concentration has been consumed and the residual gas exists in a circumnuclear ring or arms.
IRAS and Distant Galaxies
Authors: Ryohei  , Kawabe
Published: July 2016

Recent millimeter-wave observations of CO from the protogalaxy candidate IRAS F10214+4724 with single dishes and interferometers indicated that the huge amount of molecular gas is associated with the high-z galaxy with huge infrared luminosity. An overview of the results of recent observations of IRAS F10214 +4724 is shown. The implications of the results based on aperture synthesis CO observations and origin of the huge infrared luminosity (starburst or dust- enshrouded QSO) are discussed by comparing them with the “nearby” ultraluminous IRAS Galaxies.
Outflowing Molecular Gas in NGC 3079
Authors: Irwin J. A. , Sofue Y.
Published: July 2016

NMA 12CO(J=1-0) observations of the radio lobe spiral galaxy, NGC 3079, reveal a dense, rigidly rotating ring of molecular gas with a radius of about 750 pc. In addition, a tilted CO component as well as several molecular gas “spurs” are interpreted as linear features which are accelerated outwards by the nuclear outflow.
H2/CO Conversion Factor for M31 Molecular Clouds
Authors: Sofue Yoahiaki , Takabayashi Mikio , Murata Yasuhiro
Published: July 2016

The conversion factor from the CO line intensity to column density of molecular hydrogen, X = NH2/ICO is one of the most important parameters in mm-wave study of galaxies and their molecular gas (e.g., Maloney 1990). Although the same value as that obtained for our Galactic clouds (e.g. Sanders et al. 1984; Bloemen et al. 1985) has been widely applied to galaxies, it is far from trivial that the conversion factor is universal among various types of galaxies. There have been few attempts to derive the value for galaxies, and the value is still controversial if it is applicable to other galaxies or not: Approximately the same value as that for the Galaxy has been derived for M33 (Wilson and Scoville 1990, 1992), while an order of magnitude larger value is obtained for the LMC and SMC (Cohen et al. 1988; Rubin et al. 1991).

In order to obtain the conversion factor in nearby galaxies, in which individual molecular clouds can be resolved, we are conducting CO-line mapping of M31. In this paper we report a preliminary results from mapping of a north-eastern spiral arm of M31 in the 12CO(J =1 − 0) line emission using the NMA.
The Smithsonian Submillimeter Array
Authors: Ho P. T. P.
Published: July 2016

The Smithsonian Astrophysical Observatory is currently designing and constructing the Submillimeter Array (SMA). This instrument will consist of six 6-m telescopes, which can be moved and reconfigured in four concentric ring-like arrangements with maximum baselines of 500 m. Pending negotiations, the SMA will be sited on Mauna Kea at the 4000 m plateau, adjacent to the existing CSO and JCMT submillimeter telescopes. The goal of the SMA is to provide imaging at sub-arcsecond resolution for the wavelength range of 1.3 mm to 0.35 mm. This instrument will therefore improve the angular resolution achieved with present submillimeter telescopes by more than an order of magnitude. As the cool (10-100 K) dust and gas in the Milky Way and other external systems will radiate principally in the submillimeter wavelengths, we expect the SMA to provide unprecedented resolution and to make fundamental contributions to many different problems including the studies of our solar system, star formation and circumstellar disks, galaxies and molecular cloud structures, quasars and active galactic nuclei, and perhaps even galaxy formation in the early universe.
The Next Plan of the Nobeyama Radioheliograph
Authors: Takano T. , Enome S. , Nakajima H. , Shibasaki K. , Nishio M. , Hanaoka Y. , Torii C. , Sekiguchi H. , Bushimata T. , Kawashima S. , Shinohara N. , Irimajiri Y. , Koshiishi H. , Kosugi T. , Shiomi Y. , Sawa M.
Published: July 2016

A high time- and spatial-resolution radio interferometer for solar observations has been constructed at Nobeyama (Figure I.; Nakajima et al. 1994). The Nobeyama Radioheliograph consists of 84 antennas, 0.8m in diameter, arranged on a T-shape lines of 500m in the EW and 220m in the NS directions. The time resolution is 50 ms and the spatial resolution is 10”. The field of view is 40’ at the observing frequency 17GHz, which enables us to watch the whole sun. The radioheliograph has observed hundreds of flares during the few months since the beginning of regular observations in July ‘92, and such powerful performance has never before been demonstrated in the history of solar radio observations.
Recent Results on Abundance Determinations
Authors: Adelman Saul J.
Published: July 2016

I review abundance determinations of normal B5-F4 and peculiar stars published since 1984. Several analyses performed with photographic spectrograms indicate interesting stars which should be analyzed with high signal-to-noise data. Studies of stars of known ages which belong to clusters, associations, and moving groups should led to the most direct confrontations with theory. The increase in signal-to-noise ratio provided by electronic detectors with respect to photographic plates should allow accurate analyses of moderating rotating stars. High resolution, high signal-to-noise ratio studies have revealed crucial information about the line profiles of Sirius, Vega, and other A stars. It would aid comparison of analyses if we could agree on a standard set of gf-values and line damping constants. A computer bulletin board would be a useful means to provide and maintain such data as well as model atmosphere codes.
Modeling A-Type Atmospheres: NLTE Models
Authors: Hubeny Ivan , Lanz Thierry
Published: July 2016

A brief review on NLTE models of normal and chemically peculiar stars of spectral types A and late B is presented. We will concentrate on three basic question about NLTE modeling, namely i) Why (calculate NLTE models)? ii) How (to calculate NLTE models efficiently)? and iii) What (we learn from NLTE models already calculated)?
Atomic Data: Needs and Progress
Authors: Artru Marie-Christine
Published: July 2016

We summarize the newly available results which improve both the accuracy and the completeness of atomic data to be used for analysis and modelization of A stars. A major progress is obtained from the large amount of theoretical work that has been performed through the recent revision of stellar opacities. Extensive lists of accurate line data are available and we present their general characteristics. Detailed photoionization cross-sections are now available for many initial states of different atomic ions. They currently show deep resonance structures and strongly depart from the hydrogenic shapes which were often assumed. Their importance is illustrated by the example of the Si II ultra-violet features. Further implications about computation of radiative forces are pointed out.
Spectrum Analysis of the Binary Star 53 Aur with a CP3 Component
Authors: Zverko Juraj , Budaj Ján , Zboril Milan , Žižňovský Jozef
Published: July 2016

The CP-star 53 Aur (HD 47152, HR 2425) has been assigned in the literature different types of peculiarity. Bertaud (1959) classified it as A0p-EuCr, Cowley et al. (1969) as B9p-Eu(Cr?), Osawa (1965) as Hg and Zverko (1974) as Mn -type. MacAlister (1978) discovered its binary nature and Tokovinin (1986) first determined its orbit with a period of 13.7 y. Subsequent interferometric observations by Baize (1989) yielded new orbital elements with a period of 25.816 y, total mass of 5.8 M⊙ and magnitude difference of two B9 components 0.3 mag. Adelman (1982) performed spectrophotometry and fitted the Balmer jump with Teff=10 500 K, while the Paschen continuum with Teff=9 500 K, log g=4 in both cases. Palmer (1965) estimated the projected rotational velocity to 325 km s−1 from the width of the Ca II-K line, while Wolff and Preston (1975) obtained 33 km s−1 from the Mg II 448.1 nm line. In this work we analyze high-dispersion spectra obtained in two distant orbital phases, namely in 1975 and in 1992 to distinguish the components of the system.
On Stark Broadening of Heavy Element Lines in A-Type Star Spectra: Bi II Lines
Authors: Dimitrijević M. S. , Popović L. Č.
Published: July 2016

We report here results of Bi II spectral lines Stark broadening research within the modified semiempirical approach. The strong absorption Bi II lines observed in Hg – Mn star atmospheres have been investigated as well as the influence of the departure from LS – coupling and the correct knowledge of ionization potential. The obtained results have been compared with other estimations and with experimental results.
Line Identification of Schneider’s Star (BD+24°3675) Around Hβ
Authors: Kroll Reinhold
Published: July 2016

The line spectrum of BD +24°3675 is investigated from 4730 to 4990 Å. I discuss the presence of individual elements, including Rare Earths. The equivalent widths of all strong lines are given. Estimates of Teff and logg indicate that the star might be evolved with a low surface gravity. Indications for spectral line variability have been found.
Physical Parameters and Chemical Composition of Components of the Am-Type Binary System RR Lyncis
Authors: Lyubimkov L.S. , Rachkovskaya T.M.
Published: July 2016

Duplicity is a very widespread phenomenon among Am-stars. For instance, Abt (1961) investigating 25 such stars found out that 22 of them are spectroscopic binaries. However this important phenomenon is ignored usually in chemical composition investigations of Am-stars. Consequently some “mean” element abundances are determined, which can noticeably differ from real abundances in atmospheres of components. Moreover false chemical anomalies can appear, as shown by the theoretical modelling of spectra of binary stars (Lyubimkov, 1989, 1992). Meanwhile accurate data on chemical composition of Am-stars must be considered as observational test for any hypothesis suggested for explanation of these objects.
Spectral Characteristics of A-Type Stars in the Galactic Halo
Authors: Corbally C.J. , Gray R.O.
Published: July 2016

Among 67 early A-type stars at high galactic latitudes, selected to have both small m1 and large c1 Strömgren photometric indices, we find about one third to have quite normal dwarf or subgiant spectra at MK classification dispersion. Those stars with peculiarities included 10 new λ Bootis stars, though none of these appeared significantly evolved. We wonder whether some of the metal-weak dwarf stars in our set may be field horizontal-branch equivalents of the blue, downward-curving, low-luminosity end of the blue horizontal-branch stars.
A Theoretical Period-Luminosity Relation of Dwarf Cepheids
Authors: McNamara D.H. , Powell John M.
Published: July 2016

Dwarf Cepheids (large-amplitude δ Sct variables and SXPhe variables in the GCVS) are late A-type stars near light maximum and early-F stars near light minimum. In the lower part of the instability strip where these stars are found the pulsation constant Q varies only slightly. As pointed out by Andreasen, Hejlesen, and Petersen (1983) this makes it easy to transform a theoretical HR or alternatively a (logTe, logg) diagram to a theoretical logTe, logP0) diagram by the use of the relation. This follows from the equations:

where P0 is the fundamental period of pulsation. The periods, of course, can be determined with very high accuracy.
Diffusion Models for Magnetic Ap Stars
Authors: Babel J.
Published: July 2016

Progress made in spectroscopy and in the diffusion theory permits now to make severe comparisons, based on line profiles, between theory and observation.

We first review transport processes which are present in the atmospheric layers of Ap stars and discuss their relative importance. We then show that mass loss could play a key role for the creation of abundance maps. A mass loss model is proposed for 53 Cam and is compared, by spectrum synthesis, with visible and IUE high resolutions observations. The model accounts well for the line profiles of several elements with an exception for Ti. Furthermore, the abundance stratification predicted by this model gives close agreement with the large variation of the abundances of Cr and Fe found between the visible and UV domains. The diffusion-mass loss model finally permits to give a simple interpretation of the peculiar Ca II K lines observed in many Ap SrCrEu stars and in particular in 53 Cam, β CrB and HD 191742.
CP3 Stars in Open Clusters
Authors: Schneider H.
Published: July 2016

Abt published in 1979 frequencies of peculiar stars in open clusters based on published classifications for 661 stars in 14 open clusters and associations. Among others he discussed an age dependence of the frequencies of CP3 stars and found them increasing with age. Furthermore, he suggested a possible age dependence of the rotational velocity of these stars.

But the sample he used was rather small: he found eight CP3 stars in 5 open clusters. In the mean time the number of cluster CP3 stars was more than double. Therefore, the findings of Abt shall be examined on the basis of the larger sample.
Variability of 56 Ari
Authors: Czechowski W. , Stȩpień K.
Published: July 2016

From IUE archival data and visual spectrophotometric observations published by Adelman and Pyper, nearly 20 energy distributions of 56 Ari in different rotational phases were obtained. The light variations in selected spectral bands correlate with spectrum variations. The bolometric flux varies by ˜ 2.5 % over the rotation period.
Polyynes and Polycyclic Aromatic Molecules in C-rich Circumstellar Envelopes
Authors: Omont Alain
Published: July 2016

The aim of this review is to discuss our knowledge on molecules in the circumstellar environment of evolved stars. In particular the presence and the behaviour of various kinds of molecules with several or many carbon atoms, in relation to C-rich dust, is considered.

Such objects include mainly: (i) circumstellar shells of AGB carbon stars, either visible (such as Y CVn) or infrared (such as IRC+10216 (CW Leo)); (ii) planetary nebulae (PNe, e.g. NGC 7027); (iii) pre-planetary nebulae (PPNe, also called post-AGB stars, such as CRL 2688 or the Red Rectangle), probably in an intermediate evolution stage between the two former classes. I will not discuss more peculiar classes, such as R CrB stars and novae, for which very little is known about the presence of such molecular species.
Oscillator Strengths and Excited State Lifetimes in Metallic Hydrides and Oxides
Authors: Schamps Joël
Published: July 2016

It is really impressive to see the amount of information astrophysicists have been able to extract from the analysis of that faint glimmering light that stars se,nd to tell us about them. The main piece of this analysis consists in dispersing the light to get the spectrum, that is to say intensity versus wavenumbers. From the measurements of wavenumbers it is possible to identify the atomic and molecular species from comparison with high-resolution laboratory spectroscopic data. Once the constituents have been identified, models can be constructed in order to simulate the metabolism of circumstellar atmospheres. In such models a crucial point is the abundance of the identified atomic and molecular constituents.
Asteroid Surveys and other CCD Projects Using the Observatoire de la Cote D’Azur (OCA) Schmidt Telescope
Authors: Maury Alain
Published: July 2016

A wide field CCD camera has been developed for asteroid searches and has been used at our Schmidt telescope since September 1993. This paper describes this camera and its software as well as the changes it introduced in the type of programs that were requested on the telescope, and changes introduced in the way the telescope is operated.
Astronomy with the Automated Patrol Telescope
Authors: Carter B. D. , Ashley M. C. B. , Bembrick C. S. , Brooks P. W. , Mitchell P. , Storey J. W. V.
Published: July 2016

The Automated Patrol Telescope (APT) is a wide-field CCD imaging telescope operated by the University of New South Wales at Siding Spring Observatory in Australia. The optical design employed resembles that of a Schmidt, but uses a 3-element lens to achieve a wide, corrected field of view. The APT was developed by extensively modifying the optical, mechanical and electronic systems of a Baker-Nunn satellite tracking camera. Telescope motion and operation of the CCD have been placed under computer control, allowing automated observations for longterm survey and monitoring projects. The APT has 0.5 m aperture f/1 optics which produce a 5° flat field, of which a 2°×3° field is covered by the CCD currently installed. The telescope is being used for studies of stellar activity in open clusters and regions of star formation, and comet and minor planet investigations. A number of other projects for the APT are being considered, including searches for novae, supernovae in clusters of galaxies, and brown dwarfs.
Use of CCDs in Schmidt Telescopes for the Investigation of Hα Emission of Flare Stars
Authors: Szécsényi-Nagy Gábor
Published: July 2016

The use of Schmidt telescopes in their traditional mode for the detection of stellar flares and for the UV and PG photometry of these stars proved to be very productive. The fast optical system and reliable sensitivity of modern photographic emulsions resulted in a photometric time-resolution of several minutes even in the case of distant objects. One of the most important characteristics of flare stars may be the tendency for coexistence with more massive and more luminous member stars of young stellar aggregates (mainly open clusters). Although the vast majority of flare stars discovered seem to belong to clusters, a great many of them are neighbours of our sun. These can be investigated in depth because a sufficient number of their photons can be collected and recorded in narrow photometric bands or even in spectra of good resolution. The direct comparison of solar vicinity flare stars with flare-active members of distant clusters has been almost impossible. However recent developments in silicon-based photon-detecting technology offer the advantage of incredibly high detector quantum efficiency (DQE) in many spectral regions where photographic materials never reached an acceptable level. Hα emission is one of the most characteristic features of flare stars, and the wavelength of Hα photons fits extremely well with the peak of the spectral sensitivity curves of silicon photon detectors. CCD chips placed in the focal surface of Schmidt telescopes seem to be very promising for the future investigation of Hα emission of flare stars.
Multi-Fibre Spectroscopy with Schmidt Telescopes
Authors: Watson F. G.
Published: July 2016

Large Schmidt telescopes are peculiarly well-suited to multifibre spectroscopy. The extent to which the small aperture is compensated by the wide field is illustrated by the fact that the total photon throughput of the 1.2 m UK Schmidt Telescope (UKST) is almost identical to that of the 3.9 m Anglo-Australian Telescope (AAT) in its new 2-degree field (2dF) mode. In the implementation of the technique, Schmidt telescopes have a number of practical advantages, while there is no shortage of scientific problems that can be addressed. However, the instrumentation required to capitalize fully on this potential is costly and, because Schmidts are perceived as “small” telescopes with a specialist following, the required funding is likely to remain elusive.