Astronomy and Astrophysics Supplement Series

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List of Papers (Total 2,129)

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...

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...

Quasar variability: Correlations with amplitude

The relation between quasar variability and parameters such as luminosity and redshift has been a matter of hot debate over the last few years with many papers on the subject. Any correlations which can be established will have a profound effect on models of quasar structure and evolution. The sample of quasars with redshifts in ESO/SERC field 287 contains over 600 quasars in the...

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...

Absolute proper motions of open clusters - I. Observational data

Mean proper motions and parallaxes of 205 open clusters were determined from their member stars found in the Hipparcos Catalogue. 360 clusters were searched for possible members, excluding nearby clusters with distances pc. Members were selected using ground based information (photometry, radial velocity, proper motion, distance from the cluster centre) and information provided...

Blind source separation and analysis of multispectral astronomical images

Celestial sources are studied by means of multispectral analysis, for which a pixel value can be considered as a mixture of different sources. We show that the application of blind source separation methods can display interesting features, which can help astronomers to improve their description of celestial sources. Experiments were carried out on Hubble Space Telescope images...

CCD photometric search for peculiar stars in open clusters - I. NGC 2169, Melotte 105 and NGC 6250

The search for chemically peculiar (CP) stars in open clusters using photoelectric photometry sampling the presence of the characteristic flux depression feature at 5200 Å via the -system (Maitzen 1976) has so far delivered data for objects usually no more distant than 1000 pc from the Sun. A series of fourteen papers (first: Maitzen & Hensberge 1981; for the time being last...

First images on the sky from a hyper telescope

We show star images obtained with a miniature “densified pupil imaging interferometer” also called a hyper-telescope. The formation of such images violates a “golden rule of imaging interferometers” which appeared to forbid the use of interferometric arrangements differing from a Fizeau interferometer. These produce useless images when the sub-apertures spacing is much wider than...

Spectra of late type stars from 4800 to 9000 Å

We present optical spectra of 21 stars from 4800 to 8920 Å, covering essentially the late spectral types, G, K, M and the luminosity classes I and III. Half of the stars are super metal rich (SMR) ones. The spectra were obtained at a resolution of 1.25 Å using the Aurelie spectrograph, equipped with a linear array CCD-like detector, attached to the OHP 1.52 m telescope. Also...

The dust distribution inside the Large Magellanic Cloud

The distribution of the interstellar dust inside the LMC has been investigated on the basis of UBV photometry and spectral classifications of 1507 luminous O-A type stars. The mean internal reddening has been found to be rather high with . The frequency distribution of the reddenings is strongly asymmetric, so that it is useless to give an error of the mean. Reddenings up to 08...

Determination of effective temperatures for an extended sample of dwarfs and subdwarfs (F0-K5)

We have applied the InfraRed Flux Method (IRFM) to a sample of 475 dwarfs and subdwarfs in order to derive their effective temperatures with a mean accuracy of about 1.5%. We have used the new homogeneous grid of theoretical model atmosphere flux distributions developed by Kurucz (1991, 1993) for the application of the IRFM. The atmospheric parameters of the stars cover, roughly...

Analytic representations of rovibrational dipole matrix elements for the CO molecule and its isotopomers

We report new calculations of transition matrix elements for more than thirty thousand infrared lines of the CO molecule and its isotopomers inside the X ground electronic state. These lines belong to the =1, 2, 3 bands involving very high excited states such as 41 and 133. The transition matrix elements have been calculated from an accurate solution of the Schrödinger equation...

Einstein A-coefficients for vib-rotational transitions in CO

Einstein A-coefficients for vib-rotational transitions in CO isotopomers, for vibrational quantum number v up to 20, rotational quantum number J up to 140, and up to 4, are calculated. The change in J is governed by the selection rules . These coefficients play an important role in astronomy, as CO is the most abundant molecule after , and has been observed in almost all the...

CCD spectrophotometry of CVs. III. 3270-9000 Å atlas for 38 faint systems

A 7 Å resolution, 3270-9000 Å spectrophotometric atlas is presented for 38 objects from the Downes & Shara (1993) catalogue of Cataclysmic Variables (CVs). The stars were selected among those listed as lacking published spectra. As for previous papers in this series, the aim is to check the CV status of the objects spectroscopically and to provide high quality absolute...