Contents
Images
Upload your image
DSS Images Other Images
Related articles
On-line database of photometric observations of magnetic chemically peculiar stars
We present our extensive project of the On-line database ofphotometric observations of magnetic chemically peculiar stars tocollect published data of photometric observations of magneticchemically peculiar (mCP) stars in the optical and near IR regions. Nowthe nascent database contains more than 107 000 photometric measurementsof 102 mCP stars and will be continually supplemented with published ornew photometric data on these and about 150 additional mCP stars. Thisreport describes the structure and organization of the database.Moreover, for the all included data we estimated the error ofmeasurements and the effective amplitudes of the light curves.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| A catalog of stellar magnetic rotational phase curves
Magnetized stars usually exhibit periodic variations of the effective(longitudinal) magnetic field Be caused by their rotation. Wepresent a catalog of magnetic rotational phase curves, Be vs.the rotational phase φ, and tables of their parameters for 136stars on the main sequence and above it. Phase curves were obtained bythe least squares fitting of sine wave or double wave functions to theavailable Be measurements, which were compiled from theexisting literature. Most of the catalogued objects are chemicallypeculiar A and B type stars (127 stars). For some stars we also improvedor determined periods of their rotation. We discuss the distribution ofparameters describing magnetic rotational phase curves in our sample.All tables and Appendix A are only available in electronic form athttp://www.edpsciences.org
| Spectral Classification of Stars in A Supplement to the Bright Star Catalogue
MK spectral types are given for about 584 stars in A Supplement to theBright Star Catalogue. These are compared with Hipparcos parallaxes tocheck the reliability of those classifications. The estimated errors are+/-1.2 subtypes, and 10% of the luminosity classes may be wrong.
| Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars
This paper presents the catalogue and the method of determination ofaveraged quadratic effective magnetic fields < B_e > for 596 mainsequence and giant stars. The catalogue is based on measurements of thestellar effective (or mean longitudinal) magnetic field strengths B_e,which were compiled from the existing literature.We analysed the properties of 352 chemically peculiar A and B stars inthe catalogue, including Am, ApSi, He-weak, He-rich, HgMn, ApSrCrEu, andall ApSr type stars. We have found that the number distribution of allchemically peculiar (CP) stars vs. averaged magnetic field strength isdescribed by a decreasing exponential function. Relations of this typehold also for stars of all the analysed subclasses of chemicalpeculiarity. The exponential form of the above distribution function canbreak down below about 100 G, the latter value representingapproximately the resolution of our analysis for A type stars.Table A.1 and its references are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/631 and Tables 3 to 9are only available in electronic form at http://www.edpsciences.org
| Core-polarization effects in doubly ionized cerium (Ce III) for transitions of astrophysical interest
The importance of core-polarization effects on oscillator strengthdetermination in Ce III is emphasized. The inclusion of these effects inrelativistic Hartree-Fock (HFR) calculations leads to theoreticallifetime values for some 4f6p levels of this ion in close agreement withrecent time-resolved laser-induced fluorescence measurements. These newatomic data, the most accurate to date, have allowed the refinement ofthe stellar abundance determination of cerium in the chemically peculiarstar HD 192913, but have not altered in a drastic way the conclusionsderived in recent analyses regarding the overabundance of this element.
| Multiplicity among chemically peculiar stars. II. Cool magnetic Ap stars
We present new orbits for sixteen Ap spectroscopic binaries, four ofwhich might in fact be Am stars, and give their orbital elements. Fourof them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. Thetwelve other stars are: HD 9996, HD 12288, HD 40711, HD 54908, HD 65339,HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD216533. Rough estimates of the individual masses of the components of HD65339 (53 Cam) are given, combining our radial velocities with theresults of speckle interferometry and with Hipparcos parallaxes.Considering the mass functions of 74 spectroscopic binaries from thiswork and from the literature, we conclude that the distribution of themass ratio is the same for cool Ap stars and for normal G dwarfs.Therefore, the only differences between binaries with normal stars andthose hosting an Ap star lie in the period distribution: except for thecase of HD 200405, all orbital periods are longer than (or equal to) 3days. A consequence of this peculiar distribution is a deficit of nulleccentricities. There is no indication that the secondary has a specialnature, like e.g. a white dwarf. Based on observations collected at theObservatoire de Haute-Provence (CNRS), France.Tables 1 to 3 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/394/151Appendix B is only available in electronic form athttp://www.edpsciences.org
| Experimental and theoretical studies of DyIII: radiative lifetimes and oscillator strengths of astrophysical interest
The lifetimes of three short-lived levels belonging to the4f96p configuration and of two long-lived levels of the4f95d configuration of DyIII have been measured for the firsttime using time-resolved laser-induced fluorescence techniques. They arein good agreement with theoretical values calculated within theframework of a pseudo-relativistic configuration interactionapproximation. Using the experimental lifetimes and the theoreticalbranching fractions, a first set of transition probabilities ofastrophysical interest has been obtained for DyIII.
| Measurement of lifetimes by laser-induced fluorescence and determination of transition probabilities of astrophysical interest in Nd III
Selective lifetime measurements by time-resolved laser-inducedfluorescence spectroscopy for 5 levels belonging to the 4f35dconfiguration of doubly ionized neodymium provide a first and usefulexperimental test of the relativistic Hartree-Fock calculations in thision of astrophysical interest. As a consequence, the accuracy of thetransition probabilities deduced in the present work is well assessed.These new data are expected to help astrophysicists in the future torefine the analysis of the composition of chemically peculiar starswhich frequently show large overabundances of lanthanides when comparedto the solar system standards.
| Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
The Hipparcos satellite made measurements of over 9734 known doublestars, 3406 new double stars, and 11,687 unresolved but possible doublestars. The high angular resolution afforded by speckle interferometrymakes it an efficient means to confirm these systems from the ground,which were first discovered from space. Because of its coverage of adifferent region of angular separation-magnitude difference(ρ-Δm) space, speckle interferometry also holds promise toascertain the duplicity of the unresolved Hipparcos ``problem'' stars.Presented are observations of 116 new Hipparcos double stars and 469Hipparcos ``problem stars,'' as well as 238 measures of other doublestars and 246 other high-quality nondetections. Included in these areobservations of double stars listed in the Tycho-2 Catalogue andpossible grid stars for the Space Interferometry Mission.
| Multiperiodicities from the Hipparcos epoch photometry and possible pulsation in early A-type stars
A selection criterion based on the relative strength of the largestpeaks in the amplitude spectra, and an information criterion are used incombination to search for multiperiodicities in Hipparcos epochphotometry. The method is applied to all stars which have beenclassified as variable in the Hipparcos catalogue: periodic, unsolvedand microvariables. Results are assessed critically: although there aremany problems arising from aliasing, there are also a number ofinteresting frequency combinations which deserve further investigation.One such result is the possible occurrence of multiple periods of theorder of a day in a few early A-type stars. The Hipparcos catalogue alsocontains a number of these stars with single periodicities: such starswith no obvious variability classifications are listed, and informationabout their properties (e.g., radial velocity variations) discussed.These stars may constitute a new class of pulsators.
| Theoretical Oscillator Strengths inPr III and Application to Some CP Stars
A set of transition probabilities is obtained for the first time formany transitions of Pr III of astrophysical interest. A relativisticHartree-Fock method, combined with a least-squares fitting of theavailable experimental levels, including a large number of newlydetermined values, has been used for the calculations in whichconfiguration interaction and core-polarization effects have beenintroduced. The interest of the new data set is illustrated byconsidering the chemical composition of the chemically peculiar (CP)stars HD 101065 (Przybylski's star) and HD 141556 (χ Lupi).
| Ab initio calculations of oscillator strengths and Landé factors for Nd Iii
Theoretical calculations of oscillator strengths and Landég-factors made with the Cowan code are presented for the rare-earth ionNd Iii. The emphasis is on transitions in the optical region of thespectrum. Comparisons of previous ab initio calculations of this typefor other lanthanides (e.g., La Ii, Ce Iii, and Lu Ii) with publishedexperimental and theoretical data suggest that the accuracy of thelog(gf) values for individual transitions should be about +/-0.15 dex inthe absence of significant core polarization effects; the g-factorsshould be good to better than 5%, except in a few cases where termmixing is important. Applications of the data are made in thecalculation of neodymium abundances in the atmospheres of the chemicallypeculiar stars HD 101065 (``Przybylski's star") andHD 122970.
| Observing roAp Stars with WET: A Primer
We give an extensive primer on roAp stars -- introducing them, puttingthem in context and explaining terminology and jargon, and giving athorough discussion of what is known and not known about them. Thisprovides a good understanding of the kind of science WET could extractfrom these stars. We also discuss the many potential pitfalls andproblems in high-precision photometry. Finally, we suggest a WETcampaign for the roAp star HR 1217.
| On the HIPPARCOS photometry of chemically peculiar B, A, and F stars
The Hipparcos photometry of the Chemically Peculiar main sequence B, A,and F stars is examined for variability. Some non-magnetic CP stars,Mercury-Manganese and metallic-line stars, which according to canonicalwisdom should not be variable, may be variable and are identified forfurther study. Some potentially important magnetic CP stars are noted.Tables 1, 2, and 3 are available only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The observed periods of AP and BP stars
A catalogue of all the periods up to now proposed for the variations ofCP2, CP3, and CP4 stars is presented. The main identifiers (HD and HR),the proper name, the variable-star name, and the spectral type andpeculiarity are given for each star as far as the coordinates at 2000.0and the visual magnitude. The nature of the observed variations (light,spectrum, magnetic field, etc.) is presented in a codified way. Thecatalogue is arranged in three tables: the bulk of the data, i.e. thosereferring to CP2, CP3, and CP4 stars, are given in Table 1, while thedata concerning He-strong stars are given in Table 2 and those foreclipsing or ellipsoidal variables are collected in Table 3. Notes arealso provided at the end of each table, mainly about duplicities. Thecatalogue contains data on 364 CP stars and is updated to 1996, October31. This research has made use of the SIMBAD database, operated at CDS,Strasbourg, France.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Observations of Pulsating AP Stars in South Africa
Not Available
| On the effective temperatures, surface gravities, and optical region fluxes of the magnetic CP stars.
We determined effective temperatures and surface gravities for five MCPstars using ATLAS9 metal-rich model atmospheres, optical regionspectrophotometry, and Hγ profiles. The predictions of thesemodels fit the continua significantly better than do those of previousgeneration ATLAS models. They can even match the 5200A broad, continuumfeatures in three stars where this feature is of moderate strength. Asynthesized spectrum of one of these stars, HD 43819, suggests that thisfeature is at least due partially to differential line blanketing.However, problems remain in fitting the optical region energydistributions of stars with stronger 5200A features. The 4200A and the6300A features are not reproduced in the models. The relationshipbetween the strength of the 5200A feature and metallicity was alsoexplored using spectrophotometric and photometric indices.
| Wavelength identifications in the magnetic CP star HR 465 (HD 9996).
Not Available
| Catalogue of CP stars with references to short time scale variability
A catalogue was compiled which contains all references in the literaturesince 1962 related to variations of CP stars on time scales shorter thanthe rotation period. The role of this catalogue lies in the unbiasedlisting of all available references, and not in a critical evaluation.
| A new list of effective temperatures of chemically peculiar stars. II.
Not Available
| Some problems of non-reversive CP stars. I. Spatial distribution.
Not Available
| Spectrophotometry of Peculiar B-Stars and A-Stars - Part Nineteen - Variability of the Magnetic Cp-Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..101..393A&db_key=AST
| Spectroscopic study of the chemically peculiar star HD 5797
Based on 19 spectrograms with a dispersion of 17.5 A/mm, line spectrumvariations in the CP2 star HD 5797 are studied. Equivalent width andcentral depth measurements show that intensities of 34 unblended linesvary with an amplitude of about 2 times for Fe, Ti and Sr lines, and 2.5times for Cr lines. A search for improved period of the star has beencarried out. The obtained new value is: P equals 68.255 +/- 0.004 days.An attempt to give a qualitative explanation of the photometric behavioris made.
| A seven-year northern sky survey of AP stars for rapid variability
A high-speed photometric survey of 120 Ap stars in the northern sky, hasbeen conducted, between 1985 and 1991, in order to search for rapidvariability. Stars of spectral types, namely from B8 to F4, have beenselected for the survey. The selected pulsational variable stars occupythe hotter regions of the instability strip of the Hertzsprung-Russeldiagram. Noted is the absence of pulsations in the hotter B8-A3 Apstars; this does not, however, preclude the existence of pulsations,since HD 218495 was recently discovered to be a rapidly oscillating Ap(roAp) star. The primary result of this study is that variouscombinations of photometric indices, while pointing towards roAp starshaving the characteristic signatures of cool, SrCrEu stars, still failto isolate the roAp phenomenon from similar nonpulsating Ap stars.Color-magnitude and color-color diagrams are presented in order tocomplete this survey.
| On the origin of the statistical correlation between rotation periods and apparent radii for CP 2 stars
Apparent rotational velocities and rotation periods for CP 2 stars areused to study the 'apparent' radius distribution of R sin i. It impliesa distribution for the radii of CP 2 stars which is almost normal fortheir temperatures when compared to main sequence stars. However, astatistical correlation exists between rotation period P and R sin i. Itis argued that, at least in the case of silicon stars, neitherconservation of angular momentum on the main sequence, nor bias in themeasured v sin i values are able to induce a correlation of the observedstrength. Thus, one has to postulate either additional rotationalbraking depending statistically on R, or a detection bias dependingstatistically on i. It is shown that the correlation might be explainedin both ways and the implications of each possibility are discussed.
| Second supplement to the catalogue of observed periods of AP stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991A&AS...87...59C&db_key=AST
| Average Profiles and Equivalent Widths of Hydrogen Lines of 76 Normal and Peculiar Stars - Masses and Radii of Studied Stars
Not Available
| Variability of Balmer lines in AP stars
A set of beta index measurements were obtained for 22 Ap stars between1984 and 1986. Periodic variability of the beta index with therotational phase is found for 17 of the stars, and the upper limits ofvariations are determined for the remaining five stars. A model ofhorizontal and vertical chemical inhomogeneity caused by the diffusionof elements is shown to qualitatively account for the similarity andobserved phase relations between photometric and Balmer line variations,along with the observed mean amplitudes of the beta variations, for mostof the Ap stars considered.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Cocher |
| Right ascension: | 06h59m20.13s |
| Declination: | +42°18'53.2" |
| Apparent magnitude: | 6.675 |
| Distance: | 188.324 parsecs |
| Proper motion RA: | -1.1 |
| Proper motion Dec: | -6.5 |
| B-T magnitude: | 6.786 |
| V-T magnitude: | 6.685 |
Catalogs and designations:
|
INHABITED SKY
