The fundamental parameters of the Algol binary AI Draconis revisited
We present the results of an analysis of our infrared light curves ofthe Algol-type binary AI Draconis in the J, H and K bands, and ofpublished light curves in the B, V and Strömgren uvby bands,together with spectra obtained by us. The analysis of the light curveswas carried out using a code based on ATLAS model atmospheres and Rochegeometry.The small contribution of the secondary cool component to the totallight of the system in the visible, producing light curves with veryshallow secondary eclipses, makes the stellar and orbital parametersderived from light-curve analysis in the visible spectral rangeuncertain. The larger contribution of the secondary star to the infraredfluxes makes this range particularly well suited to the derivation ofprecise orbital and stellar parameters in binaries of Algol type. Fromthe simultaneous solution of the infrared JHK light curves, we derivethe following absolute orbital and stellar parameters for the twocomponents: = 10160 +/- 160 K,Req,1= 2.12 +/- 0.04 Rsolar,log()1= 4.23; = 5586 +/-110 K, Req,2= 2.36 +/- 0.04 Rsolar,log()2= 3.76; M1= 2.86 +/- 0.09Msolar, q=M2/M1= 0.44 +/- 0.03; a= 7.62+/- 0.09 Rsolar, i= 76.53°+/- 0.3°, e~= 0.0. Here, and log() indicate average surfacevalues, Req is the equivalent radius of the deformed star anda is the orbital size.In our light-curve solutions, the secondary star of AI Dra fills itsRoche lobe (as also indicated by the spectroscopy), thus discountingclaims, based on UBV light curves, that both components of the binaryare located within their Roche lobes. The visible and infraredphotometry show no evidence of any significant infrared excess in thesystem, and the distance of AI Dra is estimated as d= 169 +/- 17 pc.Based on the spectra of AI Dra and template stars in the ranges8210-9060, 6250-7130 and 4040-4920 Å, we classify the stellarcomponents of AI Dra and find that the most probable spectral types areA0V (or perhaps A1V) for the primary and F9.5V for the secondary(although it could reach as far as G4V), respectively. From ourspectroscopic observations, the spectral evolution of AI Dra withorbital phase is also presented. Furthermore, we obtain the projectedrotational velocity of the secondary, whose value turns out to becompatible with the star filling its Roche lobe.
|
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
|
Apsidal motion and light-time effect in eclipsing binaries HS Herculis and U Ophiuchi
Several new times of minima, based on photoelectric observations, havebeen secured for two bright and well-known eclipsing binaries witheccentric orbits and with very similar orbital periods: HS Her (P =1fd637 , e = 0.02) and U Oph (P = 1fd677 , e = 0.003). For HS Her, anapsidal motion with a period of 78 years is confirmed and a third bodyin an eccentric orbit with a period of 85 years is found. An analysis ofall available eclipse timings of U Oph has confirmed the presence of anapsidal motion with one of the shortest known periods (20.1 yr) and alight-time effect with the improved period of 37.6 yr. The correspondinginternal structure constants log k2 were also derived. It isestimated that the tertiaries of both systems are detectable via speckleinterferometry. Partly based on photoelectric observations secured atthe San Pedro Mártir Observatory, Baja California, Mexico.
|
A spectroscopic survey for lambda Bootis stars. II. The observational data
lambda Bootis stars comprise only a small number of all A-type stars andare characterized as nonmagnetic, Population i, late B to early F-typedwarfs which show significant underabundances of metals whereas thelight elements (C, N, O and S) are almost normal abundant compared tothe Sun. In the second paper on a spectroscopic survey for lambda Bootisstars, we present the spectral classifications of all program starsobserved. These stars were selected on the basis of their Strömgrenuvbybeta colors as lambda Bootis candidates. In total, 708 objects insix open clusters, the Orion OB1 association and the Galactic field wereclassified. In addition, 9 serendipity non-candidates in the vicinity ofour program stars as well as 15 Guide Star Catalogue stars were observedresulting in a total of 732 classified stars. The 15 objects from theGuide Star Catalogue are part of a program for the classification ofapparent variable stars from the Fine Guidance Sensors of the HubbleSpace Telescope. A grid of 105 MK standard as well as ``pathological''stars guarantees a precise classification. A comparison of our spectralclassification with the extensive work of Abt & Morrell(\cite{Abt95}) shows no significant differences. The derived types are0.23 +/- 0.09 (rms error per measurement) subclasses later and 0.30 +/-0.08 luminosity classes more luminous than those of Abt & Morrell(\cite{Abt95}) based on a sample of 160 objects in common. The estimatederrors of the means are +/- 0.1 subclasses. The characteristics of oursample are discussed in respect to the distribution on the sky, apparentvisual magnitudes and Strömgren uvbybeta colors. Based onobservations from the Observatoire de Haute-Provence, OsservatorioAstronomico di Padova-Asiago, Observatório do Pico dosDias-LNA/CNPq/MCT, Chews Ridge Observatory (MIRA) and University ofToronto Southern Observatory (Las Campanas).
|
On the Variability of A0-A2 Luminosity Class III-V Stars
We study the Hipparcos Satellite photometry of A0-A2 luminosity classIII-V stars. Most are not particularly variable. A few stars for whichfurther study is desirable are identified.
|
The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
|
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.
|
Times of Minima of Five Eclipsing Binaries
Not Available
|
The Lambda 6708 Feature in AP Stars
Not Available
|
The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
|
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.
|
Li I 6708 in normal A and F-type stars.
The 6708 A Li region has been observed in a sample of unevolved stars ofspectral type A-early F and the Li abundances have been determined byusing the synthetic spectrum method. As the intensity of the Li I 6708doublet decreases rapidly with increasing T_eff_ in these stars, we haveto pay special attention to the list of lines present in the vicinity ofthe Li feature. Uncertainties in the measured equivalent widths and inthe derived abundances are discussed in the sample of stars chosen fortheir low v sin i.
|
All-sky Stromgren photometry of speckle binary stars
All-sky Stromgren photometric observations were obtained for 303 specklebinaries. Most stars were in the range of V = 5-8. These data, whencombined with ratios of intensities from the CHARA speckle photometryprogram, will allow the determination of photometric indices for theindividual components of binary stars with separations as small as 0.05arcsec. These photometric indices will complement the stellar massesfrom the speckle interferometry observations to provide a much improvedmass-luminosity relationship.
|
ICCD speckle observations of binary stars. X - A further survey for duplicity among the bright stars
Speckle interferometric observations are reported for 1123 starsselected from the Yale Bright Star Catalogue (BSC) in a continuingeffort to detect new binaries among the bright stars. Thirty-twopreviously unresolved binaries have been detected, including companionsto Xi UMa and 15 S Mon. Measures of 107 previously resolved systems,many of which resulted from earlier speckle observations, are alsopresented. No evidence of duplicity within a specific (m, Delta-m, rho)window of detectability was found for 984 bright stars. Many of thesystems discovered earlier have shown significant orbital motions, andwe present preliminary orbital elements for six binaries. This efforthas resulted in the discovery of 75 new, bright binaries. We considersome aspects of the duplicity frequencies among the diverse spectral andluminosity classes represented in this sample. We anticipate that thecompletion of a speckle survey of the BSC would lead to the discovery ofat least 200 additional binary systems with angular separations mostlybelow 0.20 arcsec. Many of these will have periods of the order of onedecade and will be accessible to complementary radial velocity programsof enhanced precision.
|
Search for stars with intrinsic polarization.
Not Available
|
ICCD speckle observations of binary stars. II - Measurements during 1982-1985 from the Kitt Peak 4 M telescope
This paper represents the continuation of a systematic program of binarystar speckle interferometry initiated at the 4 m telescope on Kitt Peakin late 1975. Between 1975 and 1981, the observations were obtained witha photographic speckle camera, the data from which were reduced byoptical analog methods. In mid-1982, a new speckle camera employing anintensified charge-coupled device as the detector continued the programand necessitated the development of new digital procedures for reducingand analyzing speckle data. The camera and the data-processingtechniques are described herein. This paper presents 2780 newmeasurements of 1012 binary and multiple star systems, including thefirst direct resolution of 64 systems, for the interval 1982 through1985.
|
ICCD speckle observations of binary stars. I - A survey for duplicity among the bright stars
A survey of a sample of 672 stars from the Yale Bright Star Catalog(Hoffleit, 1982) has been carried out using speckle interferometry onthe 3.6-cm Canada-France-Hawaii Telescope in order to establish thebinary star frequency within the sample. This effort was motivated bythe need for a more observationally determined basis for predicting thefrequency of failure of the Hubble Space Telescope (HST) fine-guidancesensors to achieve guide-star lock due to duplicity. This survey of 426dwarfs and 246 evolved stars yielded measurements of 52 newly discoveredbinaries and 60 previously known binary systems. It is shown that thefrequency of close visual binaries in the separation range 0.04-0.25arcsec is 11 percent, or nearly 3.5 times that previously known.
|
IUE low-dispersion reference atlas
This atlas, published by ESA and essentially devoted to normal stars,presents 229 graphic spectra together with the corresponding fluxes andan ultraviolet spectral type. The preparation of this publicationconfirmed that MK classifications cannot simply be transferred to theultraviolet range. A set of transparencies illustrates the referencesequences constructed from the ultraviolet data. A magnetic-tape copy ofall the spectra pertaining to this atlas is available from the StellarData Center in Strasbourg.
|
IUE low-dispersion spectra flux catalogue. I - Normal stars (magnetic tape)
A magnetic tape catalog of the fluxes (2A-step) of 229 selectedlow-dispersion stellar spectra prepared by the Centre de Calcul deStrasbourg-Cronenbourg is presented in the form of a set of tables. Thecatalog uses the general MK frame and centers on stars exhibiting normalbehavior in the ultraviolet. All the stars included in the catalog arelisted together with their MK and UV spectral classifications. Thespectra were collected by the International Ultraviolet Explorer (IUE)with the aim of establishing reference spectral sequences in theultraviolet range.
|
Johnson BVR Magnitudes for Selected Comparison Stars
Not Available
|
Prediction of spectral classification from photometric observations - Application of the UVBY beta photometry and the MK spectra classification. II - General case
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....85...93M&db_key=AST
|
Spectrophotometry of massive eclipsing binary stars
Normalized flux distributions have been measured for U Oph, AG Per,Lambda Tau, and V356 Sgr. Light curves at 4700 A for U Oph and AG Perare used to check published eclipsing-binary-system parameters, and theparameters given by Koch and Koegler (1977) and Popper (1974) areemployed for the analysis of U Oph and AG Per, respectively. No evidenceof circumstellar matter is found for U Oph and AG Per. The resultsindicate that the spectra of Lambda Tau from phase 0.77 to 0.90 arecharacteristic of spectral type B4, that the spectra of V356 Sgr matchB3 and A0 spectra except at isolated phases exhibiting UV excess light,and that the excess-light spectrum is characteristic of hydrogenfree-bound emission. Color excesses and component-star temperatures andabsolute visual magnitudes are determined for U Oph and AG Per.
|
A new photometric analysis of U Oph.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJ...214..423K&db_key=AST
|
UVBY beta photometry and MK spectral classification.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24...69O&db_key=AST
|
Photometry of the Eclipsing Binary U Ophiuchi and of Nova Cygni 1975
Not Available
|
Four-colour and H BET photometry of some bright southern stars- II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.160..155S&db_key=AST
|
Four-color and Hβ photometry for the brighter AO type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..109C&db_key=AST
|
Magnitudes and colors for 833 Northern and Southern stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955AJ.....60...65E&db_key=AST
|
Photoelectric Studies of Five Eclipsing Binaries.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...114..297H&db_key=AST
|
INHABITED SKY
