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Forty Years of Spectroscopic Stellar Astrophysics in Japan
The development of Japanese spectroscopic stellar astrophysics in therecent 40 years is reviewed from an observational point of view. In thisarticle, the research activities are provisionally divided into fourfields: hot stars, hot emission-line (Be) stars, cool stars, and otherstars. Historical developments of the observational facilities atOkayama Astrophysical Observatory (spectrographs and detectors) are alsosummarized in connection with the progress in scientific researchactivities.
| Transition probabilities and lifetimes in singly ionized rhenium
Transition probabilities and radiative lifetimes have been obtained for45 transitions of ReII using a combination of radiative lifetime valuesobtained with the laser-induced fluorescence technique (seven levels)and theoretical branching fractions. This new set of results, concerningultraviolet and visible lines, will be useful in the future forinvestigating the composition of chemically peculiar stars.
| Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).
| Astrophysics in 2003
Five coherent sections appear this year, addressing solar physics,cosmology (with WMAP highlights), gamma-ray bursters (and theirassociation with Type Ia supernovae), extra-solar-system planets, andthe formation and evolution of galaxies (from reionization to assemblageof Local Group galaxies). There are also eight incoherent sections thatdeal with other topics in stellar, galactic, and planetary astronomy andthe people who study them.
| The 5200-Åflux depression of chemically peculiar stars - II. The cool chemically peculiar and λ Bootis stars
After establishing the synthetic Δa photometric system in thefirst paper of this series, we now present model atmospheres computedwith individual abundances for a representative sample of chemicallypeculiar (CP) stars and either confirm or redetermine their inputparameters through comparisons with photometric, spectrophotometric andhigh-resolution spectroscopic data. The final models obtained from thisprocedure were used to compute synthetic Δa indices which werecompared with observations. The observed behaviour of Δa isreproduced for several types of CP stars: models for Am stars shownegligible (or marginally positive) values of a few mmag, while forλ Bootis stars - and for metal deficient A stars in general - weobtain negative values (as low as -12 mmag in one case). For the coolestCP2 stars with effective temperatures below about 8500 K, we obtain mild(~+10 mmag) to moderately large (~+30 mmag) flux depressions inagreement with observations. However, Δa values for slightlyhotter members of the CP2 group (for which still Teff <10000 K) are underestimated from these new models. The effect of themicroturbulence parameter on the Δa index is revisited and itsdifferent role in various types of CP stars for reproducing the fluxdepression at 5200 Åis explained. We also provide reasons whymodels based on enhanced microturbulence and scaled solar abundancecould not explain the observed flux depression for all types of CPstars. We discuss potential improvements of the current models includingthe possibility of still missing line opacities (unidentified andautoionization lines), modifications due to an explicit account of aglobal stellar magnetic field, and the effect of vertical abundancestratification.
| Radiative lifetime, oscillator strength and Landé factor calculations in doubly ionized europium (Eu III)
A set of transition probabilities has been calculated for Eu IIItransitions of astrophysical interest particularly for the study ofchemically peculiar stars. They were obtained taking configurationinteraction and core-polarization effects into account. The accuracy ofthe new scale of oscillator strengths, which differs substantially fromprevious results, has been assessed through comparisons with recenttime-resolved laser-induced fluorescence measurements of radiativelifetimes.
| Cataclysmic Variables in the ``Period Gap''
This article reviews observational data on cataclysmic variables (CVs)whose orbital periods fall within the so-called period gap between 2 and3 hours. The orbital period distribution of cataclysmic variables andthe filling of the period gap by various types of CVs are demonstrated.Roughly half the stars in the period gap are magnetic, of which themajority are polars, while the other half (except a few stars) are SUUMa-type stars characterized by superbursts and superhumps. It is alsointeresting to note that those intermediate polars whose periods fallwithin the gap are among the stars with constant superhumps. The heightabove the galactic plane is estimated for the nonmagnetic stars and itis shown that, contrary to predictions, the stars in the period gap donot belong (except for one) to the spherical component of the galaxy.Light curves, some characteristic times, burst amplitudes, etc. aregiven for a number of Su UMa-type stars observed by the authors. Theevolution of superbursts from the stars NY Ser, V725 Aql, and Var73 Drais described. Observational data are presented on the classical nova VPer, a star whose period lies right in the middle of the period gap butwhose status (magnetic or nonmagnetic) has still unclear.
| Variability of the He I λ5876 Å line in early type chemically peculiar stars. II
To try to understand the behavior of helium variability in ChemicallyPeculiar stars, we continued our on-going observational campaign startedby \cite{catanzaro99}. In this paper we present a new set of timeresolved spectroscopic observations of the He I 5876 Å line for asample of 10 stars in the spectral range B3 - A2 and characterized bydifferent overabundances.This line does not show variability in two stars: HD 77350 and HD175156. It shows instead an equivalent width variation in phase with theHipparcos light curve for two stars: HD 79158 and HD 196502. Antiphasevariations have been found in 4 stars of our sample, namely: HD 35502,HD 124224, HD 129174 and HD 142990. Nothing we can say about HD 115735because of the constancy of Hipparcos photometric data, while no phaserelation has been observed for HD 90044.In the text we discuss the case of HD 175156, according to photometriccalibration and our spectroscopic observations we rule out themembership of this star to the main sequence chemically peculiar stars.We confirm the results obtained in the previous paper for which phaserelations between light, spectral and magnetic variations are notdependent on stellar spectral type or peculiarity subclass.Based on observations collected at stellar station ``M. G. Fracastoro''of the Catania Astrophysical Observatory and on observations collectedat Complejo Astrónomico El Leoncito (Casleo), which is operatedunder agreement between the Consejo Nacional de InvestigationesCientifícas y Técnicas (CONICET) and the NationalUniversities of La Plata, Córdoba and San Juan.
| Curious Variables Experiment (CURVE). Superhump Period Change Pattern in KS UMa and Other Dwarf Novae
We report extensive photometry of the dwarf nova KS UMa throughout its2003 superoutburst till quiescence. During the superoutburst the stardisplayed clear superhumps with a mean period of P_sh=0.070092(23) days.In the middle stage of superoutburst the period was increasing with arate of dot P/P=(21+/-12)*10^-5 and later was decreasing with a rate ofdot P/P=-(21+/-8)*10^-5.At the end of superoutburst and during first dozen days of quiescencethe star was showing late superhumps with a mean period ofP_late=0.06926(2) days. This phenomenon was observed even 30 days afterbeginning of the superoutburst.In quiescence the star shows quasi-periodic modulations with amplitudereaching 0.5 mag. The most common structure observed during this stagewas sinusoidal wave characterized by a period of about 0.1 days.Comparing KS UMa to other SU UMa stars we conclude that this group ofdwarf novae shows decreasing superhump periods at the beginning and theend of superoutburst but increasing period in the middle phase.
| 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
| New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
| 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
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| The laboratory analysis of Bi II and its application to the Bi-rich HgMn star HR 7775
The bismuth spectrum emitted from a hollow cathode discharge has beenrecorded with a Fourier Transform Spectrometer (FTS). Accuratewavelengths have been determined for 104 Bi Ii lines, and several newenergy levels have been found, while the accuracy of previously known BiIi level energies have been improved. The hyperfine structure of allobserved Bi Ii lines has been analyzed, yielding hyperfine constants Aand B for 56 Bi Ii levels. With the aid of the laboratory measurementsthe optical region spectrum of the HgMn star HR 7775 has been studiedfor all observable Bi Ii lines. The wavelengths and hfs constantsestablished from the laboratory work have been combined with theoreticalgf values to identify spectral lines and make an abundance estimation ofbismuth. It has been established that bismuth is present in HR 7775 atan enhancement level of approximately 5 orders of magnitude relative tothe meteoritic abundance, consistent with previous observations in theultraviolet region of this star. Astrophysical gf values are presentedfor a number of Bi Ii lines.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
| The proper motions of fundamental stars. I. 1535 stars from the Basic FK5
A direct combination of the positions given in the HIPPARCOS cataloguewith astrometric ground-based catalogues having epochs later than 1939allows us to obtain new proper motions for the 1535 stars of the BasicFK5. The results are presented as the catalogue Proper Motions ofFundamental Stars (PMFS), Part I. The median precision of the propermotions is 0.5 mas/year for mu alpha cos delta and 0.7mas/year for mu delta . The non-linear motions of thephotocentres of a few hundred astrometric binaries are separated intotheir linear and elliptic motions. Since the PMFS proper motions do notinclude the information given by the proper motions from othercatalogues (HIPPARCOS, FK5, FK6, etc.) this catalogue can be used as anindependent source of the proper motions of the fundamental stars.Catalogue (Table 3) is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strastg.fr/cgi-bin/qcat?J/A+A/365/222
| Period study of the contact system VW Cep
New photoelectric U,B and V observations of the eclipsing contact systemVW Cep were taken in 1998-2000 and 23 new minima times were determined.The (O-C) diagram constructed using photographic and photoelectricminima times can be explained by the light-time effect caused by thepresence of a third and fourth body in the system and the long-termperiod decrease interpreted by the mass transfer from the more to theless massive component or/and the magnetic-braking process. The suddenperiod increase detected in 1999 is probably a consequence of theepisodic mass transfer from the less to the more massive component.Enhanced surface activity causes short-term apparent variations of theorbital period. The differences of times of the subsequent primary andsecondary minima show two significant periodicities P_1 = 2.94 +/- 0.07years and P_2 = 2.36 +/- 0.05 years. The latter periodicity is probablythe beat period of the orbital and rotational period at the latitudes ofmost frequent occurrence of the spots.
| Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars. On the light, spectral and magnetic variability
We have equipped the spectrograph of the Catania AstrophysicalObservatory with a polarimetric module which gives simultaneouscircularly right and left polarised radiation spectra. This facility hasbeen used to perform time-resolved spectropolarimetric (Stokes V)measurements of the mean longitudinal (effective) magnetic field forseven chemically peculiar stars. Since this class of stars ischaracterised by a periodically variable magnetic field, the monitoringof the Stokes V parameter is a fundamental step to recover the magneticfield topology. To better define the variation of the effective magneticfield, we have combined our observations with data from the literature.Variability periods given in the literature have been verified usingHipparcos photometric data and, if necessary, we have re-determinedthem. From Hipparcos absolute magnitudes, we have determined the stellarradii and then, on the hypothesis of a rigid rotator, the inclination ofthe rotational axes with respect to the line of sight. On the hypothesisthat the magnetic field presents a dominant dipolar component (that is,where the Stokes Q and U parameters are not necessary to recover themagnetic configuration) we have determined the angle between therotational and dipole axes and the polar strength of the magnetic field.Chemically peculiar stars show periodic anti-phase light variationsshort-ward and long-ward of a constant wavelength, the null wavelength.We have performed numerical computations of the expected fluxdistribution for metal-enhanced atmospheres with different effectivetemperature and gravity. From the behaviour of the null wavelength, weconfirm the importance of the non-homogeneous distribution of elementson the stellar surface as origin of the light variability. However toexplain the photometric variability of some stars, we suggest that theflux distribution is also influenced by the contribution of the magneticfield to the hydrostatic equilibrium. Based on observations collected atthe Catania Astrophysical Observatory, Italy
| On the effective temperatures, surface gravities, and optical region fluxes of the CP stars
We determined effective temperatures and surface gravities for 17magnetic Chemically Peculiar (mCP) stars by comparing optical regionspectrophotometry and Hγ profiles with the predictions of ATLAS9model atmospheres. Although solar composition models can fit the energydistributions of the normal and many Mercury-Manganese stars, theycannot match the optical energy distributions of the mCP stars,especially the lambda 5200 broad, continuum regions. The role ofmetallicity and microturbulence to provide appropriate energydistributions which fit those observed for the mCP stars isinvestigated. Using metal-rich models with the opacity distributionfunctions for microturbulent velocities of 4 and 8 km s-1,their lambda 5200 broad, continuum features are often fit as part ofthis process. For some stars it is impossible to fit simultaneously boththis feature and the line blanketing in the Hγ region. Thissuggests that this continuum feature is produced by elements other thanthose which contribute most of the general line blanketing. A systematicdifference in the temperatures found by the photometric andspectrophotometric approaches is discovered for the hotter mCP stars. Aninvestigation of 10 Mercury-Manganese stars shows a similar effect. Thismay be due to the photospheric compositions becoming less solar withincreasing temperature.
| Oxygen 6156-8 Angstroms Triplet in Chemically Peculiar Stars of the Upper Main Sequence: Do HgMn Stars Show an Oxygen Anomaly?
An extensive spectrum-fitting analysis in the lambda ~ 6150 Angstromsregion was performed for forty late-B and A chemically peculiar (HgMn,Ap, Am, weak-lined) and normal stars of the upper main sequence, inorder to quantitatively establish the abundance of oxygen from the O I6156-8 triplet and to study its behavior/anomaly for each peculiaritygroup, where special attention was paid to HgMn-type stars. Magnetic Apvariables (Si or SrCrEu type) generally show a remarkably large oxygendepletion (by ~ -1.6 dex to ~ -0.4 dex relative to the solar abundance),and classical Am stars also show a clear underabundance (by ~ -0.6 dexon the average). In contrast, the oxygen abundance in HgMn stars,exhibiting only a mild deficiency relative to the Sun typically by ~0.3-0.4 dex, is not markedly different from the tendency of normalstars, also showing a subsolar abundance ([O/H] =~ -0.2). In view of therecent observational implication that the present solar oxygen abundanceis enriched by ~ 0.2-0.3 dex relative to the interstellar gas (fromwhich young stars are formed), and thus unsuitable for the comparisonstandard, we concluded that the extent of the average O-deficiency inHgMn stars is appreciably reduced down to only ~ 0.1-0.2 dex (i.e., notmuch different from the initial composition), which contrasts with theirwell-known drastically large N-depletion. Yet, as can be seen from thedelicate and tight O vs. Fe anticorrelation, this marginal deficiencyshould be real, and thus some physical process simultaneously producingO-depletion/Fe-enrichment must have actually worked in the atmosphere ofHgMn stars.
| Analysis of the Photospheric Lines of the Magnetic CP Star HR 7575
The photospheric lines in the visual region of the cool magnetic CP starHR 7575 have been analyzed using a high-dispersion spectrogram obtainedat the Dominion Astrophysical Observatory. The fully line-blanketedATLAS9 model atmospheres of 10-times the solar metal content wereemployed to calculate the elemental abundances. The effectivetemperature T_eff, derived from the optical and ultraviolet energydistributions, points to 8500 +/- 300 K, while the ionization balance ofiron is not reproduced at this effective temperature. The abundancesderived from individual Cr I, Cr II, and Fe II lines apparently dependon their effective Lande factors. This implies that the Cr and Fe linesare intensified by the strong magnetic field on HR 7575. Their abundanceenhancement is estimated to be about 0.7 dex based on a computation ofthe Unno--Beckers equation. The overall abundance patterns of HR 7575are comparable to other cool magnetic CP stars. Of the analyzedelements, only Mg and Sc have nearly solar abundances, while Cr, Mn, Sr,and rare earths are overabundant by 1 to 5 dex.
| Lifetime Measurements for Ground Term Transitions in TA II, W II, and RE II
Lifetime measurements have been made for the radiation emitted in theground term transitions of the nominal form5s^25p^65d^x6s-5s^25p^65d^x6p in Ta II (x=3), W II (x=4), and Re II(x=5). Supporting theoretical calculations have also been performed tocharacterize configuration interaction and to estimate the degree ofdecay branching of the upper levels. The lifetime measurements have beencombined with these theoretical considerations and with branchingfractions deduced from the emission measurements of Corliss & Bozmanto specify the oscillator strengths of these transitions. The resultsare discussed in the context of spectroscopic data obtained fromorbiting telescopes and applied to Hubble Space Telescope spectra toestimate the tungsten abundance in Sirius.
| A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 Stars
Ultraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories.
| EU BT III identification and EU abundance in CP stars
We report the first identification of the Eu iii lambda 6666.347 line inoptical spectra of CP stars. This line is clearly present in the spectraof HR 4816, 73 Dra, HR 7575, beta CrB, and alpha (2) CVn, while it ismarginally present or absent in spectra of the roAp stars (rapidlyoscillating Ap stars, cf. Kurtz 1990) alpha Cir, gamma Equ, HD 203932,GZ Lib (33 Lib), and HD 24712. Careful synthetic spectrum calculationsfor the Eu ii lambda 6645.11 line taking into account hyperfine,isotopic, and magnetic splittings allow us to obtain more accurate Euabundances in the atmospheres of 9 CP stars. In most cases the derivedabundances are significantly lower than the previous results reportedfor some of the stars based on coarse analysis of the famous blue Eu iilines. Assuming an ionization balance in the stellar atmospheres we givean estimate of the astrophysical oscillator strength log (gf)=1.18 +/-0.14 for the Eu iii lambda 6666.347 line. This value is obtained withouttaking into account a possible hyperfine-splitting which is unknown forthis Eu iii line. We also provide astrophysical gf-values for Eu iiilambda lambda 7221.838, 7225.151, and 8079.071.
| EU III identification and EU abundance in cool CP stars
We report the first identification of the Eu III lambda 6666.317 line inoptical spectra of CP stars. This line is clearly present in the spectraof HR 4816, 73 Dra, HR 7575, and beta CrB, while it is marginallypresent or absent in spectra of the roAp stars alpha Cir, gamma Equ, BIMic, 33 Lib, and HD 24712.
| 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.
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Atomic Data for the RE II UV 1 Multiplet and the Rhenium Abundance in the HgMn-Type Star chi LUPI
We report new laboratory spectroscopic analyses that have been conductedto acquire wavelength and oscillator strength data for lines of the ReII UV 1 multiplet. Wavelengths were determined to a sub-milliangstromaccuracy for the hyperfine and isotopic structure components fromlaboratory spectra obtained with the Lund VUV Fourier TransformSpectrometer. An absolute atomic transition probability is reported forRe II 2275.253 Angstroms, obtained from its upper level lifetime and anexperimentally determined branching fraction. The radiative lifetime ofthe z 7Po2 level was found to be 4.47+/- 0.22 ns by the method of laser-induced fluorescence. With the newatomic data, synthetic spectra were generated to fit a Hubble SpaceTelescope Goddard High Resolution Spectrograph echelle mode spectrum ofthe chemically peculiar HgMn-type star chi Lupi. The weakness of thelambda 2275.253 Angstroms feature only allowed for the determination ofan upper limit to the rhenium abundance, which was found to beconsistent with the meteoritic value. Thus, in chi Lupi, rhenium appearsto be several orders of magnitude less abundant than the apparentsurficial abundances of the slightly heavier elements Pt, Au, Hg, andTl.
| A catalogue of [Fe/H] determinations: 1996 edition
A fifth Edition of the Catalogue of [Fe/H] determinations is presentedherewith. It contains 5946 determinations for 3247 stars, including 751stars in 84 associations, clusters or galaxies. The literature iscomplete up to December 1995. The 700 bibliographical referencescorrespond to [Fe/H] determinations obtained from high resolutionspectroscopic observations and detailed analyses, most of them carriedout with the help of model-atmospheres. The Catalogue is made up ofthree formatted files: File 1: field stars, File 2: stars in galacticassociations and clusters, and stars in SMC, LMC, M33, File 3: numberedlist of bibliographical references The three files are only available inelectronic form at the Centre de Donnees Stellaires in Strasbourg, viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5), or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Observation and Astrometry data
| Constellation: | Dragon |
| Right ascension: | 20h31m30.40s |
| Declination: | +74°57'17.0" |
| Apparent magnitude: | 5.2 |
| Distance: | 127.877 parsecs |
| Proper motion RA: | 9.1 |
| Proper motion Dec: | -17 |
| B-T magnitude: | 5.301 |
| V-T magnitude: | 5.197 |
Catalogs and designations:
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