Astronomy and Astrophysics Supplement Series

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List of Papers (Total 1,649)

Young massive star clusters in nearby galaxies - II. Software tools, data reductions and cluster sizes

A detailed description is given of the data analysis leading to the discovery of young massive star clusters (YMCs) in a sample of 21 nearby galaxies. A new useful tool, ishape, for the derivation of intrinsic shape parameters of compact objects is presented, and some test results are shown. Completeness tests for the cluster samples are discussed, and ishape is used to estimate...

Stark broadening of the lower Rydberg , and lines of atomic hydrogen

This paper deals with the calculation of line widths and lineshapes of the lower Rydberg lines of atomic hydrogen () in the conditions of stellar envelopes and atmospheres - electron densities scaling from 109 to 1016 cm-3 and temperatures varying between 5000 and 40000 K. For these lines, the traditional semi-classical method breaks down, especially at low densities. Another or...

The effective temperature scale of giant stars (F0–K5) - I. The effective temperature determination by means of the IRFM

We have applied the InfraRed Flux Method (IRFM) to a sample of approximately 500 giant stars in order to derive their effective temperatures with an internal mean accuracy of about 1.5% and a maximum uncertainty in the zero point of the order of 0.9%. For the application of the IRFM, we have used a homogeneous grid of theoretical model atmosphere flux distributions developed by...

A survey of flares and current helicity in active regions

We examine the spatial and temporal relationship between chromospheric H flares and photospheric current helicities in active regions. All of the data were obtained by the vector magnetograph system at Huairou Solar Observing Station of Beijing Astronomical Observatory. We focus our analysis on NOAA Active Region 6233, which was observed on 30 August 1990. The result shows that...

Survey of bipolar outflows and methanol masers in the C32S ( and C34S (2-1) lines in the Northern sky

A survey of 158 sources (bipolar outflows and methanol masers) was carried out in the CS(2-1) and C34S(2-1) lines to measure and compare densities in a large number of bipolar outflows and in Class I and Class II methanol masers, both associated with and unrelated to bipolar outflows. The statistical characteristics of the regions, forming Class I methanol masers differ from...

Strömgren photometry of 40 Harmonia, 45 Eugenia and 52 Europa

The Asteroids 40 Harmonia, 45 Eugenia and 52 Europa have been studied photometrically. From their lightcurves synodic periods of , and , and maximum amplitudes of , and , have been deduced for 40 Harmonia, 45 Eugenia and 52 Europa, respectively. Improved solutions for the sense of rotation, sidereal period, pole orientation and shape properties are proposed.

Six years of short-spaced monitoring of the and , 28SiO maser emission in evolved stars

We present the results from a monitoring of the and , 28SiO maser emission in 21 objects, covering all types of known SiO maser emitters: 13 Mira variables, 2 long period semi regu lars (SRGs), 3 variable super giants (SGs), 2 OH/IR stars, and one young stellar object. This study has been carried out with the 13.7 meter radiotelescope of the Centro Astronómico de Yebes...

A catalog of rotational and radial velocities for evolved stars

Rotational and radial velocities have been measured for about 2000 evolved stars of luminosity classes IV, III, II and Ib covering the spectral region F, G and K. The survey was carried out with the CORAVEL spectrometer. The precision for the radial velocities is better than 0.30 km s-1, whereas for the rotational velocity measurements the uncertainties are typically 1.0 km s-1...

Starspot photometry with robotic telescopes. and by light curves of 47 active stars in 1996/97

We present continuous multicolor photometry for 47 stars from October 1996 through June 1997. Altogether, 7073 , UBV, and by data points, each the average of three individual readings, were acquired with three automatic photoelectric telescopes (APTs) at Fairborn Observatory in southern Arizona. Most of our targets are chromospherically active single and binary stars of spectral...

The luminosity function of cluster galaxies - II. Data reduction procedures applied to the cluster Abell 496

We initiated a large project aimed to estimate the Luminosity Function of galaxies in clusters and to evaluate its relation to cluster morphology. With this paper we deem necessary to outline the general procedures of the data reduction and details of the data analysis. The cluster sample includes the brightest southern ROSAT all-sky survey clusters with . These have been...

Instantaneous positions of microwave solar bursts: Properties and validity of the multiple beam observations

The multiple beam technique determine burst sources positions when their angular extent are small compared with the beam shapes. We show for the first time that we can check the above condition with the simultaneous observation using at least four beams. The developed technique is not critically dependent on source shapes. By means of simulations we found that for narrow 1 arcmin...

FARGO: A fast eulerian transport algorithm for differentially rotating disks

We present an efficient and simple modification of the standard transport algorithm used in explicit eulerian fixed polar grid codes, aimed at getting rid of the average azimuthal velocity when applying the Courant condition. This results in a much larger timestep than the usual procedure, and it is particularly well-suited to the description of a Keplerian disk where one is...

Infrared spectral sequence of quenched carbonaceous composite subjected to thermal annealing

We investigate the spectroscopic alteration through thermal annealing on the quenched carbonaceous composite (QCC) produced from hydrocarbon plasma. The emission and absorption spectra of QCC samples annealed at various temperatures indicate that the proportion of aliphatic C-H bonds in QCC decreases relative to aromatic C-H bonds with increase of annealing temperature. By...

A neutral hydrogen survey of polar ring galaxies - III.  observations and comparison with published data

A total of 50 optically selected polar ring galaxies, polar ring galaxy candidates and related objects were observed in the 21-cm  line with the  decimetric radio telescope and 31 were detected. The objects, selected by their optical morphology, are all north of declination -39, and generally relatively nearby (V < 8000 ) and/or bright ( 15.5). The  line data are presented for...

A deep echelle survey and new analysis of diffuse interstellar bands

We report a deep survey of diffuse interstellar bands (DIBs) between 3906 Å and 6812 Åunder consistent observing conditions toward three very reddened and five unreddened stars. BD+63° 1964's line-of-sight was shown to present exceptional DIB enhancement in number as well as in strength. The early spectral type of the star and the use of spectra of an unreddened comparison star...

Search and discovery tools for astronomical on-line resources and services

A growing number of astronomical resources and data or information services are made available through the Internet. However valuable information is frequently hidden in a deluge of non-pertinent or non up-to-date documents. At a first level, compilations of astronomical resources provide help for selecting relevant sites. Combining yellow-page services and meta-databases of...

The NASA Astrophysics Data System: The search engine and its user interface

The ADS Abstract and Article Services provide access to the astronomical literature through the World Wide Web (WWW). The forms based user interface provides access to sophisticated searching capabilities that allow our users to find references in the fields of Astronomy, Physics/Geophysics, and astronomical Instrumentation and Engineering. The returned information includes links...

Optical surface photometry of radio galaxies - II. Observations and data analysis

Optical imaging observations for 50 radio galaxies are presented. For each object isophotal contours, photometric profiles, structural parameters (position angle, ellipticity, Fourier coefficients), and total magnitudes are given. These observations, obtained in the Cousins R band, complement the data presented in a previous paper and are part of a larger project aimed at...

Polarization for pair annihilation in strong magnetic fields

We derive the cross-section for one-quantum annihilation of polarized electrons and positrons. The electron and positron can occupy arbitrary Landau levels and have non-zero momentum parallel to the field, and the cross-section is calculated for any polarization of the radiation. When we take zero parallel momentum for the electron and sum over photon polarization we obtain...

Modeling the imaging process in optical stellar interferometers

Optical interferometers on the ground, like ESO's Very Large Telescope Interferometer (VLTI) and the Keck Interferometer, and in space, like the InfraRed Space Interferometer (IRSI/Darwin) and the Space Interferometry Mission (SIM), will bring a major breakthrough in optical and near-infrared high angular resolution astronomy at the beginning of the next millennium. These...

CCD photometric study of the contact binary FG Hydrae

A new light curve of the contact binary FG Hya is presented in this paper. The new light curve and those obtained by other authors from 1955 to 1985 show the change in the shape of the light curves of the system. The difference in the depths between the primary and secondary eclipses increased yearly from 1955 to 1985, but the present light curve seems to exhibit the same shape...

The UMIST database for astrochemistry 1999

We report a new version of the UMIST database for astrochemistry. The previous (1995) version has been updated and its format has been revised. The database contains the rate coefficients, temperature ranges and – where available – the temperature dependence of 4113 gas-phase reactions important in astrophysical environments. The data involve 396 species and 12  elements. We have...

Multiwavelength optical observations of chromospherically active binary systems - III. High resolution echelle spectra from Ca ii H & K to Ca ii IRT

This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the Ca ii H & K to Ca ii IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines...

The ATESP radio survey - II. The source catalogue

This paper is part of a series reporting the results of the Australia Telescope ESO Slice Project (ATESP) radio survey obtained at 1400 MHz with the Australia Telescope Compact Array (ATCA) over the region covered by the ESO Slice Project (ESP) galaxy redshift survey. The survey consists of 16 radio mosaics with resolution and uniform sensitivity ( noise level ~79 μJy) over the...

Star-spots activity on BH Virginis

BH Virginis is a short-period RS CVn system. From our observations and archival sources we have gained an ephemeris by means of the times of minima. The light curves and the photoelectric observations in B and V obtained by Koch (1967) have been analyzed by using the Wilson-Devinney program. The principal results are as follows: (1) The mass ratio obtained from the photoelectric...