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Observed Orbital Eccentricities
For 391 spectroscopic and visual binaries with known orbital elementsand having B0-F0 IV or V primaries, we collected the derivedeccentricities. As has been found by others, those binaries with periodsof a few days have been circularized. However, those with periods up toabout 1000 or more days show reduced eccentricities that asymptoticallyapproach a mean value of 0.5 for the longest periods. For those binarieswith periods greater than 1000 days their distribution of eccentricitiesis flat from 0 to nearly 1, indicating that in the formation of binariesthere is no preferential eccentricity. The binaries with intermediateperiods (10-100 days) lack highly eccentric orbits.
| Extrasolar planets and brown dwarfs around A-F type stars. I. Performances of radial velocity measurements, first analyses of variations
We present the performances of a radial velocity measurement method thatwe developed for A-F type stars. These perfomances are evaluated throughan extensive set of simulations, together with actual radial velocityobservations of such stars using the ELODIE and HARPS spectrographs. Wereport the case of stars constant in radial velocity, the example of abinary detection on HD 48097 (an A2V star, with v sin{i} equal to 90 kms^-1) and a confirmation of the existence of a 3.9 M_Jup planet orbitingaround HD 120136 (Tau Boo). The instability strip problem is alsodiscussed. We show that with this method, it is in principle possible todetect planets and brown dwarfs around A-F type stars, thus allowingfurther study of the impact of stellar masses on planetary systemformation over a wider range of stellar masses than is currently done.
| Tidal Effects in Binaries of Various Periods
We found in the published literature the rotational velocities for 162B0-B9.5, 152 A0-A5, and 86 A6-F0 stars, all of luminosity classes V orIV, that are in spectroscopic or visual binaries with known orbitalelements. The data show that stars in binaries with periods of less thanabout 4 days have synchronized rotational and orbital motions. Stars inbinaries with periods of more than about 500 days have the samerotational velocities as single stars. However, the primaries inbinaries with periods of between 4 and 500 days have substantiallysmaller rotational velocities than single stars, implying that they havelost one-third to two-thirds of their angular momentum, presumablybecause of tidal interactions. The angular momentum losses increase withdecreasing binary separations or periods and increase with increasingage or decreasing mass.
| 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
| 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
| Detection of moving clusters by a method of cinematic pairs.
Not Available
| Speckle Interferometry of New and Problem HIPPARCOS Binaries
The ESA Hipparcos satellite made measurements of over 12,000 doublestars and discovered 3406 new systems. In addition to these, 4706entries in the Hipparcos Catalogue correspond to double star solutionsthat did not provide the classical parameters of separation and positionangle (rho,theta) but were the so-called problem stars, flagged ``G,''``O,'' ``V,'' or ``X'' (field H59 of the main catalog). An additionalsubset of 6981 entries were treated as single objects but classified byHipparcos as ``suspected nonsingle'' (flag ``S'' in field H61), thusyielding a total of 11,687 ``problem stars.'' Of the many ground-basedtechniques for the study of double stars, probably the one with thegreatest potential for exploration of these new and problem Hipparcosbinaries is speckle interferometry. Results are presented from aninspection of 848 new and problem Hipparcos binaries, using botharchival and new speckle observations obtained with the USNO and CHARAspeckle cameras.
| UVBY photometry of the chemically peculiar stars HD 15980, HR 1094, 33 Gem, and HD 115708
Differential Strömgren uvby photometry obtained with the FourCollege Automated Photoelectric Telescope shows that the hot HgMn star33 Gem is photometrically constant. The Si star HD 15980 is found to bea variable whose period is significantly greater than 2 years. Theunusual magnetic chemically peculiar Co star HR 1094 is discovered to bea low amplitude photometric variable with the magnetic field period ofHill & Blake, 2.9761 days. The ephemeris for the magnetic chemicallypeculiar star HD 115708 of Wade et al. is confirmed with the error inits period of 5.07622 days being greatly reduced. The {u}, {v}, {b}, and{y} light curves for both HR 1094 and HD 115708 exhibit differenceswhich indicate complex elemental photospheric abundance distributions.Tables 3-6 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/Abstract.html
| The ROSAT all-sky survey catalogue of optically bright main-sequence stars and subgiant stars
We present X-ray data for all main-sequence and subgiant stars ofspectral types A, F, G, and K and luminosity classes IV and V listed inthe Bright Star Catalogue that have been detected as X-ray sources inthe ROSAT all-sky survey; several stars without luminosity class arealso included. The catalogue contains 980 entries yielding an averagedetection rate of 32 percent. In addition to count rates, sourcedetection parameters, hardness ratios, and X-ray fluxes we also listX-ray luminosities derived from Hipparcos parallaxes. The catalogue isalso available in electronic form via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| Spectral energy distributions and physical parameters of the atmospheres of main-sequence A stars with infrared excesses: Comparison with normal stars
For eight stars with infrared excesses greater than 0.5m in the IRASbands, we obtained the energy distribution over the range 3200-7600Angstroms and measured their infrared JHKLM magnitudes. Similarobservations were performed for 21 stars of various subclasses of thespectral type A with excesses no greater than 0.3m. Based on the energydistribution derived from the response curves of the photometric UBV andWBVR systems, we computed the synthetic B-V color indices, which are ingood agreement with the photometric observations. A comparison of thenormalized energy distribution in the spectra of A stars with infraredexcesses greater than 0.5m in the IRAS bands and the mean energydistribution for stars of the corresponding subclasses shows that themaximum difference does not exceed 10% both in the ultraviolet(3200-4000 Angstroms) and in the near infrared (up to 7600 Angstroms) Inall of the stars studied, we detected no excesses in the JHKLM bandsthat were greater than the accuracy of our measurements. Using themethod of infrared fluxes and comparing the observed energy distributionwith theoretical models of Kurucz, we determined the effectivetemperatures and angular diameters of the stars. For three stars, weestimated the parameters of their dust shells.
| ICCD Speckle Observations of Binary Stars.XV.An Investigation of Lunar Occultation Systems
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996AJ....112.2260M&db_key=AST
| The photoelectric astrolabe catalogue of Yunnan Observatory (YPAC).
The positions of 53 FK5, 70 FK5 Extension and 486 GC stars are given forthe equator and equinox J2000.0 and for the mean observation epoch ofeach star. They are determined with the photoelectric astrolabe ofYunnan Observatory. The internal mean errors in right ascension anddeclination are +/- 0.046" and +/- 0.059", respectively. The meanobservation epoch is 1989.51.
| 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
| Far-Ultraviolet (912--1900 Angstrom ) Energy Distribution in Early-Type Main-Sequence Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...449..280C&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.
| Photometric calibriation of the international Ultraviolet Explorer (IUE) for high resolution spectra
We present and discuss the high resolution absolute calibration for theSWP, LWP and LWR cameras on board IUE. The calibration was implementedin routine processing on 27 December, 1987 at VILSPA and on 30 August,1990 at GSFC. The calibration is applicable to high resolution spectraprocessed with the 'new' version of the IUE spectral image processingsoftware which was implemented in routine on 10 November, 1981 at GSFCand 11 March, 1982 at VILSPA. The high resolution calibration, for theway it is defined, is primarily determined by the efficiency of theshort or long wavelength spectrographs in the high resolution, relativeto the low resolution observing modes. This interpretation is consistentwith the high resolution calibration being the same for LWP and LWRspectra (which are obtained through the same spectrograph) and beingconstant with time. It is shown that the data extraction becomescritical for the higher orders of the IUE echelle spectrographs, causinghigh resolution calibration to depend on the data extraction algorithmused below about 1350 A in the SWP and below about 2350 A in the LWP andLWR cameras.
| Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available
| Energy Distribution Data in the Spectra of 72 Stars in the Region Lambda 3200A to 7600A
Not Available
| Illinois occultation summary. II - 1979
Lunar occultation records are presented for the third year of acontinuing program. Included are 17 observations of stars brighter thanseventh magnitude, 13 reappearances, four angular diameter measurements,and seven observations of stars that are either binary or may be double.The observations were made with Stromgren y filter, the u or b filter,or the FI filter described in the first paper of this series (Radick andLien, 1980). Five observations, including four of Aldebaran, were madewith two filters centered on or near H-alpha.
| Observed and computed UV spectral distribution of A and F stars
An automatic and fast procedure was implemented to determineTe and log g from the comparison of the UV S 2/68 spectrawith the Kurucz models. The method has been applied to all A and F starswith (B-V)0 greater than or equal to 0 and luminosity classes III, IV,IV-V, and V, included in the Ultraviolet Bright-Star SpectrophotometricCatalogue. From the analysis, it appears that the models match theobserved fluxes fairly well and that the effective temperatures derivedfrom the UV data agree with those derived from Stromgren photometricindices within 200 K.
| Apparent radii and other parameters for 416 B5 V-F5 V stars of the catalogue of the Geneva Observatory
Apparent radius, visual brightness, effective temperature and absoluteradius for 416 B5 v-F5 v stars of the catalogue of the GenevaObservatory (Rufener, 1976) have been determined. Twenty-eight stars,anomalous in log a" versus (m~)o diagrams, have been singled out. A goodcorrelation for seven stars, in common with the list of Hanbury Brown etal. (1974), has been found. Similar parameters determined for 279 B5v-F5 v stars of two preceding papers (Fracassini et al., 1973, 1975)have allowed us to determine the averaged diagrams , and versus (B -V)0 for 695 B5 v-F5 v stars. Moreover, in the present paper a goodcorrelation versus and carefulrelation = -7.40 + 3.31 for B5v-F5 V stars have been determined. Plain correlations between log R/R0and blanketing parameter m2 for some spectral types seem to point outthat there are real differences in the absolute radii of stars of thesame spectral type, in agreement with recent researches on the HRdiagram (Houck and Fesen, 1978). Systematic differences between double(spectroscopic and visual) and single stars are found. In particular,the averaged relation versus shows that A2v-F5 v double stars may have a higher metallicity index m2 and smallerabsolute radii than single stars. Finally, the diagram log v sin iversus log R/R0 confirms some properties of binary systems found byother researchers (Huang, 1966; Plavec, 1970; Levato, 1974; Kitamura andKondo, 1978)
| Illinois occultation summary. I - 1977-1978
Results are presented for the first two years of a program for therecording of lunar occultations primarily of bright stars or objects ofspecial interest. Observations were obtained using a single-channelCassegrain photometer at a 1-m reflector using various filters toprovide spectral definition, with the tracking of guide stars used toachieve telescope pointing. Of the 64 events observed, 30 were of starsbrighter than 7 magnitudes, 40 were reappearances, four were used forangular diameter measurements, eight were binary star observations andsix may indicate multiple stars.
| Spectral classification from the ultraviolet line features of S2/68 spectra. III - Early A-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...33...15C&db_key=AST
| Absolute luminosity calibration of Stroemgren's 'intermediate group'
A relation defining the luminosity index for Stroemgren's (1966)intermediate group (A0 to A3 stars) in terms of absolute magnitude iscalibrated using a method based on the principle of maximum likelihood.This relation is also calibrated for the case when the 'a' index iscorrected for reddening. For both relations, calculations are made ofthe magnitude dispersion, the mean velocity components and correspondingdispersion, and the precision of each parameter. The results are shownto be in fairly good agreement with Stroemgren's (1966) values, and arelation incorporating the corrected 'a' index is proposed formain-sequence stars. The absolute magnitudes obtained with a relation ofthe present type are compared with those derived from trigonometricparallaxes and with those obtained by Eggen (1972).
| 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
| Narrow-band photometry of early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....12....5H&db_key=AST
| A catalogue of proper motions for 437 A stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..189F&db_key=AST
| Photoelectric observations of early A stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..165J&db_key=AST
| Catalogue d'etoiles O et B.
Not Available
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Observation and Astrometry data
| Constellation: | Δίδυμοι |
| Right ascension: | 06h42m24.30s |
| Declination: | +17°38'43.0" |
| Apparent magnitude: | 5.21 |
| Distance: | 42.717 parsecs |
| Proper motion RA: | 8.7 |
| Proper motion Dec: | -84.5 |
| B-T magnitude: | 5.299 |
| V-T magnitude: | 5.225 |
Catalogs and designations:
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