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Eccentricity generation in hierarchical triple systems: the planetary regime
In previous papers, we developed a technique for estimating the innereccentricity in hierarchical triple systems, with the inner orbit beinginitially circular. We considered systems with well-separated componentsand different initial setups (e.g., coplanar and non-coplanar orbits).However, the systems we examined had comparable masses. In the presentpaper, the validity of some of the formulae derived previously is testedby numerically integrating the full equations of motion for systems withsmaller mass ratios (from 10-3 to 103, i.e.systems with Jupiter-sized bodies). There is also discussion aboutHD217107 and its planetary companions.
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| A near-IR stellar spectral library in the H band using the Mt. Abu telescope
We present an H band near-infrared (NIR) spectral library of 135 solartype stars covering spectral types O5-M3 and luminosity classes I-V asper MK classification. The observations were carried out with 1.2 meterGurushikhar Infrared Telescope (GIRT), at Mt. Abu, India using a NICMOS3HgCdTe 256 x 256 NIR array based spectrometer. The spectra have amoderate resolution of 1000 (about A) at the H band and have beencontinuum shape corrected to their respective ective temperatures. Adetailed paper describing all the aspects of this spectral library hasbeen published in Ranade et. al. (2004).
| Analysis of the Dynamic Stability of Selected Multiple Stars with Weak Hierarchy
The stability of multiple systems with known orbital elements and withsubsystems occupying adjacent hierarchy levels is analyzed using sixstability criteria and numerical simulations of their dynamicalevolution. All the stability criteria considered are in qualitativeagreement with the numerical computations. Of the 16 systems studied, 11are confirmed to be stable and five (HD 40887, HD 136176, HD 150680, HD217675, and HD 222326) may be unstable on time scales of 106 yr orless. The small dynamical ages of the unstable systems may indicate thatthey have captured components during encounters between close binariesand field or moving cluster stars. The instability could also resultfrom the perturbation of a stable system when it approaches a massiveobject (star, black hole, or molecular cloud). It is possible that someof the unstable systems are remnants of small clusters or stellargroups.
| 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.
| B Star Rotational Velocities in h and χ Persei: A Probe of Initial Conditions during the Star Formation Epoch?
Projected rotational velocities (vsini) have been measured for 216 B0-B9stars in the rich, dense h and χ Persei double cluster and comparedwith the distribution of rotational velocities for a sample of fieldstars having comparable ages (t~12-15 Myr) and masses (M~4-15Msolar). For stars that are relatively little evolved fromtheir initial locations on the zero-age main sequence (ZAMS) (those withmasses M~4-5 Msolar), the mean vsini measured for the h andχ Per sample is slightly more than 2 times larger than the meandetermined for field stars of comparable mass, and the cluster and fieldvsini distributions differ with a high degree of significance. Forsomewhat more evolved stars with masses in the range 5-9Msolar, the mean vsini in h and χ Per is 1.5 times thatof the field; the vsini distributions differ as well, but with a lowerdegree of statistical significance. For stars that have evolvedsignificantly from the ZAMS and are approaching the hydrogen exhaustionphase (those with masses in the range 9-15 Msolar), thecluster and field star means and distributions are only slightlydifferent. We argue that both the higher rotation rates and the patternof rotation speeds as a function of mass that differentiatemain-sequence B stars in h and χ Per from their field analogs werelikely imprinted during the star formation process rather than a resultof angular momentum evolution over the 12-15 Myr cluster lifetime. Wespeculate that these differences may reflect the effects of the higheraccretion rates that theory suggests are characteristic of regions thatgive birth to dense clusters, namely, (1) higher initial rotationspeeds; (2) higher initial radii along the stellar birth line, resultingin greater spin-up between the birth line and the ZAMS; and (3) a morepronounced maximum in the birth line radius-mass relationship thatresults in differentially greater spin-up for stars that become mid- tolate-B stars on the ZAMS.
| The BAA Observers' Workshops: Observing eclipsing variables: a beginners' guide
The General Catalogue of Variable Stars (GCVS)1 lists many differentclasses of variable star. Some of these are well known and contain manymembers; others are more obscure and contain only a few examples.However, it is also possible to split variable stars into just two basiccategories: the intrinsic variables ? stars like Mira variables, Cepheidvariables, novae and supernovae ? in which the stars themselves arevarying in brightness, and the extrinsic variables, in which theindividual stars themselves do not actually vary, and prominent amongthese are the eclipsing variables.
| An Apparent Descriptive Method for Judging the Synchronization of Rotation of Binary Stars
The problem of the synchronous rotation of binary stars is judged byusing a synchronous parameter Q introduced in an apparent descriptivemethod. The synchronous parameter Q is defined as the ratio of therotational period to the orbital period. The author suggests severalapparent phenomenal descriptive methods for judging the synchronizationof rotation of binary stars. The first method is applicable when theorbital inclination is well-known. The synchronous parameter is definedby using the orbital inclination i and the observable rotationalvelocity (V1,2 sin i)M. The method is mainly suitable for eclipsingbinary stars. Several others are suggested for the cases when theorbital inclination i is unknown. The synchronous parameters are definedby using a1,2 sin i,m1,2 sin3 i, the mass function f (m) andsemi-amplitudes of the velocity curve, K1,2 given in catalogue ofparameters of spectroscopic binary systems and (V1,2 sin i)M. Thesemethods are suitable for spectroscopic binary stars including those thatshow eclipses and visual binary stars concurrently. The synchronousparameters for fifty-five components in thirty binary systems arecalculated by using several methods. The numerical results are listed inTables 1 and 2. The statistical results are listed in Table 3. Inaddition, several apparent descriptive methods are discussed.
| A near-infrared stellar spectral library: I. H-band spectra.
This paper presents the H band near-infrared (NIR) spectral library of135 solar type stars covering spectral types O5-M3 and luminosityclasses I-V as per MK classification. The observations were carried outwith 1.2 meter Gurushikhar Infrared Telescope (GIRT), at Mt. Abu, Indiausing a NICMOS3 HgCdTe 256 x 256 NIR array based spectrometer. Thespectra have a moderate resolution of 1000 (about 16 A) at the H bandand have been continuum shape corrected to their respective effectivetemperatures. This library and the remaining ones in J and K bands oncereleased will serve as an important database for stellar populationsynthesis and other applications in conjunction with the newly formedlarge optical coude feed stellar spectral library of Valdes et al.(2004). The complete H-Band library is available online at: http://vo.iucaa.ernet.in/~voi/NIR_Header.html
| 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.
| Tidal and rotational effects in the perturbations of hierarchical triple stellar systems. I. Numerical model and a test application for Algol
A new numerical integrator has been developed for studying the orbitaland spin evolution of hierarchical triple stellar systems. The codeincludes equilibrium tide approximations with arbitrary direction ofrotational axes. The variation of the orbital elements (e.g. theinclination of the close - eclipsing - binary) and its observationalconsequences according to the distorted models with differentmass-distributions of the stars, as well as with and without dissipationare studied in the case of the well-known eclipsing triple systemAlgol. We found that, in the absence of the tidaldissipation, the presence of the third star may cause suddenfluctuations in the orbital elements and the stellar rotation of thebinary members even in the previously synchronized case, too. Thedissipation can eliminate these fluctuations, nevertheless somevariations which would produce observable effects in the same orderwhich have been measured in several eclipsing binaries are also present.Appendices are only available in electronic form athttp://www.edpsciences.org
| Catalogue of Algol type binary stars
A catalogue of (411) Algol-type (semi-detached) binary stars ispresented in the form of five separate tables of information. Thecatalogue has developed from an earlier version by including more recentinformation and an improved layout. A sixth table lists (1872) candidateAlgols, about which fewer details are known at present. Some issuesrelating to the classification and interpretation of Algol-like binariesare also discussed.Catalogue is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/263
| The eclipsing binary star RZ Cas. I. First spectroscopic detection of rapid pulsations in an Algol system
In a first report on the results of a multi-site campaign in 2001 ofphotometric and spectroscopic observations of the active semi-detachedAlgol-type system RZ Cas, we concentrate on the radial velocity (RV)variations. Using weak absorption lines we obtain an improved orbitalsolution for both components. In the orbital RV curve we observe astrong, asymmetric rotation effect. For the first time we detect rapidspectroscopic multi-mode pulsations in an Algol system. Whereas thephotometrically observed oscillations were dominated by monoperiodicpulsations at frequency 64.19 c d-1 until the year 2000, wefind in 2001 a multiperiodic behaviour with two dominant frequencies off1=56.600 c d-1 and f2=64.189 cd-1.Both modes show amplitude variations over the orbital phase with a aminimum at orbital phases φ= 0.6-0.8 and a maximum just after theprimary minimum (f2) and at φ ≈ 0.25 (f1).The different shape of amplitude modulation of the f1 andf2 modes points to different (l,m) mode structures. Themodulation itself can be explained by assuming a variable extinction dueto gas streams and an inhomogeneous accretion annulus that weakens thelight from different regions of the primary depending on its orbitalposition. This assumption is well supported by the gas densitydistribution obtained in preliminary hydrodynamic simulations.We found strong variations and cycle-to-cycle variable shapes of theorbital RV-curves of Balmer lines that have maximum magnitude in theHα line indicating a strong variability of mass-transfer rates anda non-stationary circumbinary envelope.The research is based on spectroscopic observations made with the 2-mtelescope at the Thüringer Landessternwarte Tautenburg, Germany.Table 3 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/413/293
| Infrared L'band (lambda-cen- ~3.9 mu-m) observations with TIFR near-infrared camera (TIRCAM).
TIRCAM is based on the SBRC InSb Focal Plane Array (58 x 62 pixels)sensitive between 1- 5 μm. TIRCAM system is described in Ojha et al.(2002). TIRCAM had its first light observations during March-April 2001from Gurusikhar 1.2m PRL telescope at Mt. Abu. After having thesuccessful first run in 2001, the TIRCAM was used for the L bandobservations of a few scientific targets in combination with freshtelescope mirrors in Nov. 2002 &Jan. 2003 (the aluminising operationof the primary &secondary mirrors of 1.2m telescope was carried outin mid 2002). Several at 3.9 μm. We could detect the stars upto ~ 7mag in L band from the Gurusikhar site. The TIRCAM L mag of detectedstars in Trapezium cluster were compared with the L band (3.5 μm)data of Muench et al. (2002). These measurements are in good agreementwith each other considering the two different center wavelengths. Weplan to explore TIRCAM's performance in the broad L (3.5 μm) &M(4.5 μm) bands from Hanle site in near future.
| The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
| On the detectability of long period perturbations in close hierarchical triple stellar systems
We study the possibility of the detection of the low amplitude long (P')period perturbative effect of a distant third companion on the motion ofa close binary. We give a new, more accurate analytical formula for thiskind of perturbation affecting the moments of the times of minima ineclipsing binaries. The accuracy of this formula is tested by numericalintegrations carried out for several initial configurations. We alsodescribe a numerical method based on a non-linear Levenberg-Marquardtalgorithm which makes it possible to separate this dynamical effect fromthe pure geometrical light-time effect in the eclipsing O-C diagram. Thecapabilities of this new method are demonstrated by the analysis ofnumerically simulated O-Cs for test systems having physical parametersvery similar to Algol and IU Aur.The results show that the above mentioned effect would be detectable inthese systems nowadays, observing almost each minima events in a 1-2year-long interval.
| Eccentricity generation in hierarchical triple systems with coplanar and initially circular orbits
We develop a technique for estimating the inner eccentricity inhierarchical triple systems with well-separated components. Weinvestigate systems with initially circular and coplanar orbits andcomparable masses. The technique is based on an expansion of the rate ofchange of the Runge-Lenz vector for calculating short period terms byusing first-order perturbation theory. The combination of the shortperiod terms with terms arising from octupole level secular theoryresults in the derivation of a rather simple formula for theeccentricity of the inner binary. The theoretical results are testedagainst numerical integrations of the full equations of motion.Comparison is also made with other results on the subject.
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| Envelope Ejection: An Alternative Evolutionary Process for Some Early Case B Binaries
We discuss the evolution of binaries with moderately high masses (~10-30Msolar) and with periods of ~3-300 days, corresponding mostlyto early case B. These are usually thought to evolve either byreasonably conservative Roche lobe overflow, if the initial mass ratiois fairly mild, or else by highly nonconservative common-envelopeevolution, with spiral-in to short periods (hours, typically), if theinitial mass ratio is rather extreme. We discuss here a handful ofbinaries from part of this period range (~50-250 days), which appear tohave followed a different path: we argue that they must have lost alarge proportion of initial mass (~70%-80%) but without shortening theirperiods at all. We suggest that their behavior may be due to the factthat stars of such masses, when evolved also to rather large radii, arenot far from the Humphreys-Davidson limit, where single stars lose theirenvelopes spontaneously in P Cygni winds, and so have envelopes that areonly lightly bound to the core. These envelopes therefore may berelatively easily dissipated by the perturbing effect of a companion. Inaddition, some or all of the stars considered here may have been closeto the Cepheid instability strip when they filled their Roche lobes. Oneor the other, or both, of high luminosity and Cepheid instability, incombination with an appropriately close binary companion, may beimplicated.
| Rotational Velocities of B Stars
We measured the projected rotational velocities of 1092 northern B starslisted in the Bright Star Catalogue (BSC) and calibrated them againstthe 1975 Slettebak et al. system. We found that the published values ofB dwarfs in the BSC average 27% higher than those standards. Only 0.3%of the stars have rotational velocities in excess of two-thirds of thebreakup velocities, and the mean velocity is only 25% of breakup,implying that impending breakup is not a significant factor in reducingrotational velocities. For the B8-B9.5 III-V stars the bimodaldistribution in V can be explained by a set of slowly rotating Ap starsand a set of rapidly rotating normal stars. For the B0-B5 III-V starsthat include very few peculiar stars, the distributions in V are notbimodal. Are the low rotational velocities of B stars due to theoccurrence of frequent low-mass companions, planets, or disks? Therotational velocities of giants originating from late B dwarfs areconsistent with their conservation of angular momentum in shells.However, we are puzzled by why the giants that originate from the earlyB dwarfs, despite having 3 times greater radii, have nearly the samerotational velocities. We find that all B-type primaries in binarieswith periods less than 2.4 days have synchronized rotational and orbitalmotions; those with periods between 2.4 and 5.0 days are rotating withina factor 2 of synchronization or are ``nearly synchronized.'' Thecorresponding period ranges for A-type stars are 4.9 and 10.5 days, ortwice as large. We found that the rotational velocities of the primariesare synchronized earlier than their orbits are circularized. The maximumorbital period for circularized B binaries is 1.5 days and for Abinaries is 2.5 days. For stars of various ages from 107.5 to1010.2 yr the maximum circularized periods are a smoothexponential function of age.
| Magnetic survey of bright northern main sequence stars
The first results of a systematic search for magnetic fields in thebrightest upper main sequence (MS) stars are presented. The main goal isto survey the stars with about the same detection limit and to improveexisting statistics of their magnetism. The target list contains 57upper MS stars and represents well B0.5-F9 stars. High-resolution Zeemanspectra were obtained for 30 stars of the list. The accuracy of themagnetic field measurements ranges from 20 to 300 G depending mainly onspectral class. In the majority of studied stars we did not detectmagnetic fields. In some stars we suspect the presence of a weakmagnetic field. These are the best candidates for more extensivestudies. A particular case is the star chi Dra where we probablydetected the global magnetic field. The longitudinal field strength isB_l= -54+/-12 G. Further observations of this star are needed to confirmthe detection and to ascertain if the magnetic field is variable withthe period of rotation. Based on observations collected at the 1 mtelescope of the Special Astrophysical Observatory (Nizhnij Arkhyz,Russia).
| Complex Period Variations in the Binary System IM Aurigae
Results of a new light-curve analysis and period variation study of theeclipsing binary IM Aur are presented. Four solutions are givenaccording to the different spectral types of the primary, available inthe literature. Multicolour photometry and the period analysis bothindicate a close (~ 0farcs1 ) third physical member. If it is consideredas a main-sequence star, then its spectral type is A2V-A8V, with a massof m3~1.7-2.5 Msun. The light-time effect ismodelled by the authors' simultaneous secular and periodic terms fittingcode. Clear evidence of a secular period change is also revealed. Thedetailed effects of the perturbations by a third member of a closebinary system are extensively studied, using one of the authors' latestnumerical integrator code. Although the amplitudes of the expected O-Cchanges are too small and also the data set is far undersampled forclear confirmation of the theoretical expectation of the thirdbody-perturbed eclipsing binary O-C curve, some typical patterns areshown for their possible identification amongst the O-C curves of othercloser systems (like Algol, lambdaTau) in the near future.
| Evidence of a Third Star Orbiting the Eclipsing Binary δ Librae
Radial velocity observations obtained at the Kitt Peak NationalObservatory in 1981, 1983, 1984, and 1991 confirm the suggestion made byMcLaughlin six decades ago that the bright Algol-type binary δLibrae has a long-period companion. An analysis of this eclipsingsystem's barycentric velocity for these four epochs and four earlierones where published observations were available yield thesespectroscopic elements for its center of mass: P=2.762+/-0.001 yr,K=5.46+/-0.15 km s-1, e=0.28+/-0.05,ω=198deg+/-7deg, and T=1983.24+/-0.04. Fromthese results, it can be inferred that the third star's mass andspectral type are 0.95+/-0.04 Msolar and G9 and that theentire δ Lib system is even more similar to the archetypaleclipsing binary β Persei (Algol) than was previously recognized.The spectroscopic orbital elements for the B9.5 V primary star in theeclipsing system are also updated.
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| Effects of Perturbing Forces on the Orbital Stability of Planetary Systems
We consider dynamical effects of additional perturbative forces due tothe non-point-mass nature of stars and planets: effects such asquadrupolar distortion and tidal friction in the systems of exoplanets.It is shown that one should not neglect these forces while modeling thedynamics of planetary systems, especially taking into account theundefined real masses of the planets due to unknown orbital inclinationsand the unsatisfactory application of Keplerian fits to the radialvelocity data in multiple planetary systems.
| A Complete Survey of Case A Binary Evolution with Comparison to Observed Algol-type Systems
We undertake a comparison of observed Algol-type binaries with a libraryof computed Case A binary evolution tracks. The library consists of 5500binary tracks with various values of initial primary massM10, mass ratio q0, and period P0,designed to sample the phase-space of Case A binaries in the range-0.10<=logM10<=1.7. Each binary is evolved using astandard code with the assumption that both total mass and orbitalangular momentum are conserved. This code follows the evolution of bothstars to the point where contact or reverse mass transfer occurs. Theresulting binary tracks show a rich variety of behavior that we sortinto several subclasses of case A and case B. We present the results ofthis classification, the final mass ratio, and the fraction of timespent in Roche Lobe overflow for each binary system. The conservativeassumption under which we created this library is expected to hold for abroad range of binaries, where both components have spectra in the rangeG0 to B1 and luminosity classes III to V. We gather a list of relativelywell-determined, observed hot Algol-type binaries meeting thiscriterion, as well as a list of cooler Algol-type binaries, for which weexpect significant dynamo-driven mass loss and angular momentum loss. Wefit each observed binary to our library of tracks using aχ2-minimizing procedure. We find that the hot Algolsdisplay overall acceptable χ2, confirming theconservative assumption, while the cool Algols show much less acceptableχ2, suggesting the need for more free parameters, such asmass and angular momentum loss.
| Far-Ultraviolet Spectra of B Stars near the Ecliptic
Spectra of B stars in the wavelength range of 911-1100 Å have beenobtained with the Espectrógrafo Ultravioleta de RadiaciónDifusa (EURD) spectrograph on board the Spanish satellite MINISAT-01with ~5 Å spectral resolution. International Ultraviolet Explorer(IUE) spectra of the same stars have been used to normalize Kuruczmodels to the distance, reddening, and spectral type of thecorresponding star. The comparison of eight main-sequence stars studiedin detail (α Vir, ɛ Tau, λ Tau, τ Tau, αLeo, ζ Lib, θ Oph, and σ Sgr) shows agreement withKurucz models, but observed fluxes are 10%-40% higher than the models inmost cases. The difference in flux between observations and models ishigher in the wavelength range between Lyα and Lyβ. Wesuggest that Kurucz models underestimate the far-ultraviolet (FUV) fluxof main-sequence B stars between these two Lyman lines. Computation offlux distributions of line-blanketed model atmospheres including non-LTEeffects suggests that this flux underestimate could be due to departuresfrom LTE, although other causes cannot be ruled out. We found that thecommon assumption of solar metallicity for young disk stars should bemade with care, since small deviations can have a significant impact onFUV model fluxes. Two peculiar stars (ρ Leo and ɛ Aqr) and twoemission-line stars (ɛ Cap and π Aqr) were also studied. Ofthese, only ɛ Aqr has a flux in agreement with the models. The resthave strong variability in the IUE range and/or uncertain reddening,which makes the comparison with models difficult. Based on thedevelopment and utilization of the Espectrógrafo Ultravioleta deRadiación Difusa, a collaboration of the Spanish InstitutoNacional de Técnica Aeroespacial and the Center for EUVAstrophysics, University of California, Berkeley.
| Survey of Hα Mass Transfer Structures in Classical Algol-Type Binaries
Five years of Hα survey data for 37 ``classical'' Algol-typebinaries are presented. All these systems have primaries with a spectraltype of A or B, have a period of less than 5 days, and are visible inthe Northern Hemisphere. Data were collected with the 1.02 m reflectorat the US Naval Observatory, Flagstaff Station. The survey consists ofover 460 system spectra. Each system was observed at least once duringthe 5 years, with many systems observed several times over severalepochs. Difference profiles are calculated for most spectra by modelingand subtracting the spectrum of the photospheres of the stellarcomponents. We examined each spectrum for the presence of mass transfer,stream-star and stream-disk interaction, a disk or circumstellar bulge,and chromospheric emission. We present information on the prevalence ofmass transfer activity, disk presence, and system states associated withparticular mass transfer structures. We show that no currently publishedstudy, including this one, has enough data for a rigorous statisticalidentification of system states.
| 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
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Observation and Astrometry data
| Constellation: | Ταύρος |
| Right ascension: | 04h00m40.80s |
| Declination: | +12°29'25.0" |
| Apparent magnitude: | 3.47 |
| Distance: | 113.507 parsecs |
| Proper motion RA: | -8.3 |
| Proper motion Dec: | -11.9 |
| B-T magnitude: | 3.265 |
| V-T magnitude: | 3.388 |
Catalogs and designations:
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INHABITED SKY
