bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absolute Magnitude Determination of Be Stars: The Inadequacy of the 2200 Å Bump
Authors: Doazan V. , De La Fuente A. , Barylak M. , Cramer N. 
Published: July 2016

AbstractWe present fax UV observations of Pleione made with the IUE satellite at two epochs: in 1979, when the star exhibited a strong shell spectrum and, in 1991, when it showed a Be-type spectrum. Between these two epochs, the 2200 Å bump changed dramatically, thus, rendering it inadequate for interstellar extinction/distance determination.
The Nobeyama Millimeter Array
Authors: Morita Koh-Ichiro 
Published: July 2016

AbstractThe present status and the upgrading projects for the Nobeyama Millimeter Array are described. The array is currently being upgraded to produce higher sensitivity and new spectral windows. The major items have been a new 10-m antenna, new receivers, and a new correlator. There follows a brief summary of the astronomical research is presented.
The CSO-JCMT Submillimeter Interferometer
Authors: Carlstrom J. E. , Hills R. E. , Lay O. P. , Force B. , Hall C.G. , Phillips T. G. , Schinckel A. E. 
Published: July 2016

AbstractA linked submillimeter-wave interferometer using the CSO 10.4 m and the JCMT 15 m telescopes located on Mauna Kea at an elevation of 4200 m, has been built and tested successfully. The capabilities of the instrument and an outline of the type of observations that can be made with a single, fixed-baseline interferometer are given. In particular, an experiment to detect gas infalling onto low-mass protostellar sources is proposed. The design of the instrument is described briefly and the successful results of the first tests are summarized.
The 6m mm-VLBI telescope at Kagoshima, Japan
Authors: Omodaka Toshihiro , Morimoto Masaki , Kawaguchi Noriyuki , Kitamura Yoshimi , Tanaka Minoru , Kuji Seisuke , Miyazawa Keisuke , Miyaji Takeshi , Mikoshiba Hiroshi , Hayashi Risao , Kitagawa Takahiro , Maneki Jyunya , Suzuyama Tomoya , Inoue Makoto , Fujishita Mitsumi , Sasao Tetsuo , Furuya Ley , Miyasato Kazuhide , Jike Takaaki 
Published: July 2016

VLBI observations of millimeter wavelengths can probe the broad line emission and jet forming regions of quasars, and the scale of an accretion disk around massive black holes in nearby active galaxies, which are self-absorbed at longer wavelengths. Therefore, the extension of the mm-VLBI network is timely and urgent problem. We are now planning to move Nobeyama 6 m mm VLBI telescope to Kagoshima. The telescope will be placed at Kinkohwan park in Kagoshima City in late 1992 and will be operated in 1993. The frequencies for VLBI observations will range from 22 GHz to 100 GHz.To date, there are two mm-VLBI facilities in Japan: Nobeyama 45 m and Kashima 34 m, However, the longest baseline is only about 200km EW which provides a fringe separation of 17 mas. This is not sufficient for high resolution mapping. A 10 m telescope which is under construction at Mizusawa, 400 km north from Kashima which will be usable up to 43 GHz and will add a north-south baseline, which is very important for astrometrie measurement.
IF Fiber Optics and Digital Correlating Spectrometer on the JCMT-CSO Interferometer
Authors: Lay O.P. , Hills R.E. , Carlstrom J. 
Published: July 2016

This paper describes the delay lines designed and built for the JCMT-CSO submillimeter interferometer located on the summit of Mauna Kea, Hawaii and described in the paper by Carlstrom et al. in these proceedings.One of the major features of the project is the use of fiber optics instead of coaxial cable to bring the IF signals (l-2GHz) from the receivers to the spectral line correlator via a set of fiber optic delay lines. Optical fiber now has many advantages over coax including very large bandwidth, low loss, economical cost and size and immunity to electrical interference.Soares et al. (these proceedings) describe a delay line system that can be used with a broadband continuum correlator requiring very fine delay steps The JCMT-CSO interferometer was intended to be used primarily with a digital correlating spectrometer that has a range of built-in delays, greatly easing the demand on delay line resolution.
The Massive Cloud Core Sgr B2(M): Starburst Triggered by a Cloud Collision
Authors: Miyawaki Ryosuke , Hasegawa Tetsuo , Sato Fumio , Whiteoak John B. , Kobayashi Hideyuki 
Published: July 2016

AbstractWe have observed Sgr B2 with NMA.Blue- and redshifted features revel the structure of massive core. Massive core was formed by a cloud collision and massive star formation took place by means of collapse of massive core.
An Accretion Disk Model for the Innermost 200PC of the Galaxy
Authors: Duschl W.J. , Linden S.v. , Biermann P.L. 
Published: July 2016

AbstractWe demonstrate that it is possible to understand observed radial velocities of molecular clouds close to the Galactic Center as being due to motion of this material in an accretion disk. Our models indicate a stationary disk with a radial mass flow rate of 10-1.8 Mʘ/yr with a viscosity of 1.9 · 103 pc km/s at 100 pc from the Galactic Center and a radial dependence of it, that goes approximately like the square root of the radius from the Galactic Center.
Aperture Synthesis Maps of NH2D and CH3OD Lines Toward Orion-KL: The Origin of NH3 and CH3OH
Authors: Saito S. , Mikami H. , Yamamoto S. , Murata Y. , Kawabe R. 
Published: July 2016

AbstractThe 111−-101+ transition of NH2D and the 21−20 E transition of CH3OD were mapped toward Orion-KL with the Nobeyama Millimeter Array. The synthesized beamwidth is 4″ to 5″. NH2D and CH3OD are mainly distributed over the peak-intensity regions of NH3 and CH3OH in Orion A, respectively. These results suggest that “most” of the gas-phase ammonia and methanol in the region of Orion-KL originate from dust grains.
Snapshot Observations of Circumstellar Material Around Young Stellar Objects
Authors: Despois D. , Masset F. , André P. , Baudry A. , Montmerle T. , Cabrit S. 
Published: July 2016

AbstractWe have undertaken 3mm continuum and 13CO line observations of 10 Young Stellar Objects with the Plateau de Bure Interferometer (PdBI) in a snapshot mode. We discuss here mainly the continuum dust emission (opacity index β and source extent).
The Starburst in the Nucleus of NGC 6764: The Near-IR/Radio/Optical Connection
Authors: Cameron Murray , Eckart Andreas , Genzel Reinhard , Nakai Naomasa , Wagner Stefan 
Published: July 2016

Knowledge of the distribution and excitation of gas close to the nuclei of starburst galaxies is an essential element in the construction of models dealing with intense, but short-lived, star forming events. Building a comprehensive picture of the concentrations of various gaseous components in such regions calls for a multi-wavelength approach: the principal cooling lines of cold (T≤200K) molecular gas fall in the millimetre waveband, those of hot (T~1−3×103K) excited molecular material in the near-IR, and those pinpointing starburst activity in the optical. In many cases the extents of the emitting regions are on the order of only a few arcseconds.As part of such a study into the relationship between various near- and circum- nuclear gaseous components in starburst galaxies, we have obtained data on NGC 6764, a barred spiral classified as a LINER, at resolutions of 1″−4″ across the optical, near-infrared and millimetre wavelength regimes. In a previous paper (Eckart et al. 1991) we discussed extensive single dish millimetre and JHK near-IR measurements of the nucleus and disk of NGC 6764. Here we present new near-IR observations obtained with the MPE FAST instrument (Rotaciuc et al. 1991) at the William Herschel Telescope, along with 2″ resolution 12CO J=1-0 (115 GHz) interferometry measured with the Nobeyama millimeter array and 1″ optical spectroscopy from the 3.5m Calar Alto telescope.
SOFIA: Stratospheric Observatory for Infrared Astronomy
Authors: Davidson J. A. , Erickson E. F. 
Published: July 2016

SOFIA will be a 2.5 meter telescope installed in a Boeing 747 aircraft. It will replace NASA’s smaller Kuiper Airborne Observatory (KAO), which for the past 18 years has provided the only routine access to most of the vital infrared spectrum (1 - 1000 µm). The aircraft platform opens a valuable window to the universe by enabling measurements of infrared radiation from celestial sources which the Earth’s atmosphere absorbs at lower altitudes. SOFIA will have 10 times the sensitivity and 3 times the angular resolution of the KAO throughout most of the infrared spectrum.SOFIA will be operated during its 20 year lifetime as an international facility for astronomy. It would fly 160 astronomy missions per year for about 50 science teams, selected by annual peer review. Nearly a third of these teams will furnish the observatory with specialized instrumentation, including array cameras, polarimeters, and several types of spectrometers. The frequent flight opportunities with state-of-the-art instruments guarantee extensive community participation and hands-on training of young scientists.
Exploring Abundance and Isotope Anomalies in CP Stars with the HST/GHRS: High Resolution UV Spectroscopy of χ Lupi
Authors: Leckrone David S. , Wahlgren Glenn M. , Johansson Sveneric G. , Adelman Saul J. 
Published: July 2016

AbstractWe are using the HST/GHRS in a long-term program to obtain UV spectra of unprecedented resolution and precision for bright, ultra-sharp-lined Bp (HgMn) stars and comparable normal stars. To date we have doubled the number of heavy elements for which abundances may be estimated in χ Lupi, and have obtained the first observations of Hg III lines with which to test diffusion scenarios for its extreme Hg isotope anomaly.
Similarities and Differences between Magnetic and Non-Magnetic CP Stars
Authors: Lanz Thierry 
Published: July 2016

AbstractThis brief review discusses the similarities between CP stars, focusing on magnetic fields and chemical abundances. New evidence for the presence of a magnetic field with a complex structure in some CP1 stars is presented. Small-scale structures on the surface of these stars may be connected with such a field, and the resulting effects on the curve-of-growth have been investigated. Finally, the changes during evolutionary time-scales on surface abundances are advocated as one possible reason of the large observed scatter in the chemical anomalies inside given groups of CP Stars.
The Impact of Reddening on the Observed Fluxes of a Stars
Authors: Bonifacio Piercarlo , Castelli Fiorella 
Published: July 2016

AbstractWe compare observed ultraviolet and visible flux distributions, for a sample of A-type stars, with computed fluxes obtained with version 9 of the ATLAS code (Kurucz, 1970) in order to asses the impact of reddening. We also make a comparison between determinations of reddening from UV colour indices and visible wide band (Johnson) and intermediate band (Strömgren) colour indices. We discuss the implications on the study of slightly reddened high galactic latitude stars.
The Colors of Am Stars
Authors: Shylaja B.S. , Babu G.S.D. 
Published: July 2016

AbstractThe energy distribution of the Am stars are affected by the line blanketing, which appears as a deviation in the behaviour of color indices with reference to the normal stars. In this paper we study the various color indices along with the data from IRAS and try to identify a realistic representative of the effective temperature. An excess in the IR also becomes apparent in some cases.
The Effective Temperature of Am Stars
Authors: Megessier C. , van’t Veer C. 
Published: July 2016

AbstractThe values of the effective temperature derived for Am stars by the infra-red flux method and from the Balmer line profiles are in very good agreement. They are hotter by more than 300K than the Teff given by Lane and Lester (1984) and cooler by about 200K than those obtained by Dworetsky et al (1986).
Elemental Abundances of Sharp-Lined Metallic-Lined and Comparable Normal Stars
Authors: Koçer Dursun , Adelman Saul J. , Bolcal Çetin , Hill Graham 
Published: July 2016

AbstractWe are performing elemental abundances of sharp-lined metallic-lined stars and normal late A through middle F stars using 2.4 Å mm−1 photographic region spectrograms taken with the coudé spectrograph of the 1.4-m telescope of the Dominion Astrophysical Observatory. Our initial studies of the Am stars 15 Vul and 32 Aqr and the normal stars θ Cyg (F4 V) and ɩ Psc (F7 V) showed that the elemental abundances of the normal stars were close to solar while 15 Vul shows smaller abundance anomalies than does 32 Aqr. These analyses are being done consistently with SJA’s studies of the HgMn and hotter normal stars.
Stellar Spots-Heating and Cooling Diamagnetically
Authors: Steinitz Raphael , Goldstein Ulzan 
Published: July 2016

AbstractDiamagnetic effects as heating and cooling mechanisms at stellar surfaces have been ignored in the past. This is due to the misconseption that the effect, when averaged over a velocity distribution, vanishes. We explore here the relevance of the effect to the observed luminosity and color modulations observed in CP stars.
A New Model for Stellar Magnetism
Authors: Browne P.F. 
Published: July 2016

AbstractDifferent drift velocities of electrons and ions in response to viscous forces exerted by neutral atoms generate current density j and magnetic field B, where B is proportional to vorticity ω of the fluid. Magnetic vortex tubes (MVTs) form arrays on a hierarchy of scales. MVTs are basic to the magnetism of all astrophysical systems, conferring a structure of aligned filaments. In the Sun a torsional oscillation generates oscillatory vorticity, and hence an oscillatory magnetic field. The same mechanism is proposed for the Ap stars, but with “pole-on” viewing. Resonance-line radiation pressure segregates elements within MVTs of Ap stars, where the anomalous concentrations are preserved. However, variation of the 30 MG magnetic fields of AM Her white dwarfs may be due to precession of an MVT. There is reason to attribute common magnetic flux to the Sun, Ap stars, white dwarfs and neutron stars
Have Non-Magnetic Stars a Complex Geometry?
Authors: Catalano Francesco A. 
Published: July 2016

AbstractThe existence of non-magnetic CP stars among the ones in the CP2 and CP4 groups is discussed. Assuming to be non-magnetic a star in which the magnetic field has been measured but no value in excess of the 3σlevel has been detected, the implications of the spectrum and/or light variability observed in some such stars are discussed. Since the overall properties ofnon-magneticstars do not differ significantly from those of the magnetic ones and a similar variability phenomenology has been observed in several such stars, the probable presence of a weak large scale organized magnetic field is argued.
Parameters Teff and L/L⊙ for a Group of λ Bootis Candidate Stars and their Evolutionary Status
Authors: Gerbaldi M. , Zorec J. , Castelli F. , Faraggiana R. 
Published: July 2016

AbstractThe Teff value, according to the definition of this parameter, is computed with the procedure described; the observations are then compared with the flux distribution from Kurucz’ LTE blanketed models for various values of the metallicity parameter [Z/H].Then we derive the bolometric luminosity L/L⊙ by combining the stellar bolometric flux with the values of the trigonometric parallaxes and of the colour excess found in the literature. These luminosities are then plotted on evolutionary sequences; from the position of some λ Boo stars (ρ Vir and π1 Ori), we argue that their evolutionary stage, if interpreted as that of stars having left the main sequence, is too late to keep the λ Boo abundance anomalies.These same λ Boo stars, plotted on pre-main sequence evolutionary tracks, would indicate increasing λ Boo character when the stars are approaching the main sequence showing the strongest character in λ Boo and 29 Cyg, the two stars nearest the ZAMS.
Steady State Diffusion Processes Under Turbulent Conditions. Gallium and Aluminium Cases
Authors: Budaj Ján , Zboril Milan , Zverko Juraj , Žižňovský Jozef , Klačka Jozef 
Published: July 2016

AbstractThe stationary state of the element stratification under appropriate turbulence is investigated. Equation of the stationary state is derived and solved under several simplifications. Cases of Ga and Al are studied. Al is predicted to be underabundant, but the abundance is rising with decreasing effective temperatures of the stars. Different results obtained using two methods of finding the stationary Ga stratification are indicated.
Spectral Diagnoses of Chromospheres and Winds in A-Type Stars
Authors: Lanz Thierry , Hubeny Ivan 
Published: July 2016

AbstractSo far, neither chromospheres nor stellar winds have been directly detected in main-sequence A stars. While radiative diffusion requires extremely weak stellar winds to reproduce chemical anomalies (10−15 to 10−12M⊙yr−1), two independent direct searches for mass loss set up upper limits to 10−10 M⊙yr−1, which is still several orders of magnitude higher. We discuss some new recent possibilities to detect chromospheres which arise thanks to new NLTE model atmospheres. In the near future, some progress is also expected from new observations of Lyman α with HST and from the increased sensitivity of ROSAT in the X-ray domain.
Periodic Radio Emission from the Helium Rich Stars HD 37017 and σ Ori E
Authors: Leone Francesco , Umana Grazia 
Published: July 2016

AbstractDrake et al. (1987) detected, for the first time, radio emission from magnetic Chemically Peculiar stars. They suggested that radio emission is consistent with gyrosynchrotron emission from continuously injected, mildly, relativistic particles trapped in a magnetic equatorial belt.Leone (1991) showed that it is possible considering that the radio emission comes from magnetic poles and is due to the electron component of the wind flowing along the open field lines. As a consequence Leone (1991) put forward the hypothesis that such emission could be periodically variable.In order to verify the surmise of a periodic radio emission, the magnetic Chemically Peculiar stars HD 37017 and σ Ori E have been monitored with the VLA at 6 cm.By combining our data with those obtained by Drake et al. (1987) and Philips & Lestrade (1988), we show that the radio emission from HD 37017 and σ Ori E varies with the rotational period.
White Dwarfs
Authors: Thejll Peter 
Published: July 2016

It is the intention of this review to explain what white dwarfs are and why it is interesting to study them, and why the H+2molecule is of special interest.The evolution, from start to finish, of a star of mass less than about 2 solar masses (M⊙), can roughly be summarized as follows:–A cloud of gas contracts from the interstellar medium until hydrogen ignites at the center and amain sequence(MS) star forms. H is transformed to He and the MS phase continues until H is exhausted in the stellar core.–H continues burning in a shell outside the He core while the core contracts. He “ashes” are added to the core, and ared giantstar is formed as the envelope expands. The star evolves up the Red Giant Branch (RGB) (i.e. it becomes more and more luminous and the surface cools).–Towards the end of the RGB phase, mass-loss from the upper layers increases until helium to carbon burning in the core ignites suddenly under degenerate conditions – this is called theHelium Flash(HF). The HF terminates the RGB evolution, and therefore also the mass-loss and the growth of the stellar core.–The star readjusts its structure and the He-core burns steadily on thehorizontal branch(HB) (a phase of nearly-constant luminosity) until fuel is exhausted in the He-core.–Then the C/O core contracts anew and the expansion of the envelope, and the growth of the core, during He-shell burning, mimics RGB evolution but relatively little mass is added to the core this time.–The second ascent of the giant branch (the so-called Asymptotic Giant Branch, or AGB) continues with increased mass loss towards the end–Rapid detachment of a considerable fraction of the remaining envelope and the hot core takes place, sometimes observable as thePlanetary Nebulae(PN) phase.–The PN is dispersed as the core contracts to a white dwarf (WD).–The WD cools for a long time, as internal kinetic energy and latent heat is released.
Molecules in the Sun and Molecular Data
Authors: Grevesse Nicolas , Sauval A. Jacques 
Published: July 2016

Molecules play a unique role in solar spectroscopy in allowing to derive, with high accuracy, the temperature structure of the photospheric layers from where the solar spectrum in the near ultraviolet, visible and infrared emerges. They also allow to observe the heterogeneous structure of the outer layers as well as the subtle convective motions in the layers just above the solar convection zone. Molecules play also a unique role in defining the solar chemical composition, at least as far as the very important elements like carbon, nitrogen and oxygen are concerned. They also offer the unique opportunity to derive meaningful isotopic ratios for C and O. Although we shall not deal with sunspots in the present review, it has to be recalled that molecules are the only tracers to derive the solar abundances of CI and F from the rotation-vibration lines of HC1 and HF present in the infrared sunspot spectra (Hall &amp; Noyes 1972; Hall &amp; Noyes 1969).On the other hand, the Sun itself offers a unique opportunity to produce molecular transitions, in local thermodynamic equilibrium (LTE), at rather high temperatures (T ∼ 5000 K), higher in any case than in the laboratory, often in non LTE (see review by Johnson in this volume). Therefore, new lines and new transitions of higher excitation appear in the solar spectrum allowing to use the Sun as a “permanent laboratory source” in order to refine the molecular constants. Furthermore, the solar photosphere, where we believe the physical conditions and physical processes are better known than in any other stars, offers a unique possiblity to test basic molecular data like dissociation energies and transition probabilities.
A Search for M32-like Galaxies in the Fornax Cluster using Flair
Authors: Holman Brett , Drinkwater Michael , Gregg Michael 
Published: July 2016

AbstractResults of a spectroscopic search for M32-like compact elliptical galaxies in the Fornax cluster are presented. None were found, which suggests that these objects represent the low luminosity end of the giant elliptical luminosity function, rather than being formed by tidal stripping. The sample is used to investigate the large-scale distribution of bright ellipticals.
A Magnitude Limited Redshift Survey near the SGP
Authors: Parker Quentin A. 
Published: July 2016

AbstractA description of a magnitude limited redshift survey covering 9 adjacent UKST fields is presented together with some initial results. The survey is currently ∼ 90% complete to bj ≤ 17.1. The compilation of ∼ 1700 redshifts will form one of the largest, independent, contiguous, well sampled and most homogeneous redshift catalogues currently available. The special features of this catalogue are its coverage (∼ 330deg2), mean sampling depth (∼ 125h–1 Mpc) and field to field photometric accuracy (bj ± 0.05). Morphological classifications have also been determined for all galaxies in the survey fields down to bj ≤ 17.1 and COSMOS image parameters are also available. This extensive catalogue should prove a valuable database for many projects but particularly in delineating the detailed structure in the large scale galaxy distribution.