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Fourier-Doppler imaging of non-radial pulsations in gamma Doradus stars .
This paper deals with a class of non-radial pulsators along the mainsequence, namely the gamma Doradus stars for which much effort iscurrently made in order to constrain their pulsation characteristics.However, because of their relatively low amplitude (few tens of mmag inphotometry) and due to the long time scales of the variation (between0.3 and 3 days), the detection and identification of their pulsations israther difficult, using the photometric data only. Consequently, thespectroscopic studies of the stars having well-known photometricproperties are very valuable and we study in detail the line profilevariability (LPV) in gamma Doradus candidates observed at Observatoirede Haute-Provence during a two-year high-resolution spectroscopycampaign. The non-radial behavior of selected stars is revealed with theadvent of Doppler Mapping and two-dimensional Fourier-Doppler Imagingmethods for line-profile analysis, which allowed us to detect andidentify the pulsation modes described below.
| Non-radial pulsations in the γ Doradus star HD 195068
We present high resolution spectroscopic observations of the γDoradus star HD 195068. About 230 spectra werecollected over 2 years. Time series analysis performed on radialvelocity data shows a main peak at 1.61 d-1 , a frequency notyet detected in photometry. The Hipparcos photometric 1.25d-1 frequency is easily recovered as is 1.30 d-1while the third photometric frequency, 0.97 d-1 , is onlymarginally present. The good quality of our data, which includes 196spectra collected over seven consecutive nights, shows that both the1.61 d-1 and intermediate 1.27 d-1 (mixture of1.25 and 1.30 d-1 ) frequencies are present in the lineprofile variations. Using the Fourier-Doppler Imaging (FDI) method, thevariability associated with 1.61 d-1 can be successfullymodeled by a non-radial pulsation mode ℓ=5± 1, |m|=4±1. For the intermediate frequency 1.27 d-1 we deduceℓ=4± 1, |m|=3± 1. Evidence that the star is notpulsating in the radial mode (ℓ=0) rules out a previousclassification as an RR Lyrae type star. We investigate the timevariability of FDI power spectra concluding that the observed temporalvariability of modes can be explained by a beating phenomenon betweenclosely spaced frequencies of two non-radial modes. The distribution ofthe oscillation power within the line profile indicates that there is asignificant tangential velocity component of oscillations characteristicof high radial order gravity modes which are predicted to be observed inγ Doradus type stars.
| The frequency ratio method and the new multiperiodic γ Doradus star HD 218427
Oscillations of γ Dor-type were discovered in the star HD 218427through simultaneous uvby photometric observations carried out in theyear 2003. A few Hβ-Crawford measurements were also collected forcalibration purposes and they locate this star well inside the γDor instability region. We find HD 218427 to be deficient in metals,similar to other well-defined γ Dor stars, and discuss thepossibility that it has a λ Boo nature. We carried out frequencyanalysis for different filters, including the combined "vby" filter, andfive frequencies were found as significant with periods ranging between0.3 and 0.8 days. The recently-developed frequency ratio method is usedin order to identify the excited modes. The results are consistent withan l=2 identification for all the modes and with high radial quantumnumbers (n40) for the three main observed periodicities. Thepossibility of multiplet structures is also discussed. However, noconsistency is found when using the time-dependent convection treatmentto discriminate modes. This disagreement can be due to the largerotation velocity taking place in HD 218427 and, consequently, thesignificant coupling between the modes.
| A spectroscopic study of southern (candidate) γ Doradus stars. I. Time series analysis
We present the results of a spectroscopic study of 37 southern(candidate) γ Doradus stars based on échelle spectra. Theobserved spectra were cross-correlated with the standard templatespectrum of an F0-type star for easier detection of binary and intrinsicvariations. We identified 15 objects as spectroscopic binaries,including 7 new ones, while another 3 objects are binary suspects. Atleast 12 objects show composite spectra. We could determine the orbitalparameters for 9 binaries, of which 4 turned out to be ellipsoidalvariables. For 6 binaries, we estimated the expected time-base of theorbital variations. Clear profile variations were observed for 17objects, pointing towards stellar pulsation. For 8 of them, we haveevidence that the main spectroscopic and photometric periods coincide.Our results, in combination with prior knowledge from the literature,lead to the classification of 10 objects as new bona fide γDoradus stars, 1 object as a new bona fide δ Scuti star, and 8objects as constant stars. Finally, we determined the projectedrotational velocity by two independent methods. The resulting v sin ivalues range from 3 to 135 {km s-1}. For the bona fideγ Doradus stars, the majority has v sin i below 60 {kms-1}.
| Prospects for population synthesis in the H band: NeMo grids of stellar atmospheres compared to observations
Context: .For applications in population synthesis, libraries oftheoretical stellar spectra are often considered an alternative totemplate libraries of observed spectra, because they allow a completesampling of stellar parameters. Most of the attention in publishedtheoretical spectral libraries has been devoted to the visual wavelengthrange.Aims.The goal of the present work is to explore the near-infraredrange where few observed fully calibrated spectra and no theoreticallibraries are available.Methods.We make a detailed comparison oftheoretical spectra in the range 1.57-1.67 μm for spectral types fromA to early M and for giant and dwarf stars, with observed stellarspectra at resolutions around 3000, which would be sufficient todisentangle the different groups of late-type stars. We selected theNeMo grids of stellar atmospheres to perform this comparison.Results.Wefirst demonstrate that observed spectral flux distributions can bematched very well with theoretical ones for almost the entire parameterrange covered by the NeMo grids at moderate resolution in the visualrange. In the infrared range, although the overall shape of the observedflux distributions still matches reasonably well, the individualspectral features are reproduced by the theoretical spectra only forstars earlier than mid F type. For later spectral types the differencesincrease, and theoretical spectra of K type stars have systematicallyweaker line features than those found in observations. Thesediscrepancies are traced back to stem primarily from incomplete data onneutral atomic lines, although some of them are also related tomolecules.Conclusions.Libraries of theoretical spectra for A to early Mtype stars can be successfully used in the visual regions for populationsynthesis, but their application in the infrared is restricted to earlyand intermediate type stars. Improving atomic data in the near infraredis a key element in making the construction of reliable libraries ofstellar spectra feasible in the infrared.
| Time-dependent convection seismic study of five γ Doradus stars
We apply for the first time the time-dependent convection (TDC)treatment of Gabriel and Grigahcène et al. to the photometricmode identification in γ Doradus (γ Dor) stars. We considerthe influence of this treatment on the theoretical amplitude ratios andphase differences. Comparison with the observed amplitudes and phases ofthe stars γ Dor, 9 Aurigae, HD 207223 = HR 8330, HD 12901 and48501 is presented and enables us to identify the degree l of thepulsation modes for four of them. We also determine the mode stabilityfor different models of these stars. We show that our TDC models agreebetter with observations than with frozen convection models. Finally, wecompare the results obtained with different values of the mixing-lengthparameter α.
| Frequency ratio method for seismic modelling of γ Doradus stars. II. The role of rotation
The effect of rotation on the Frequency Ratio Method (Moya et al. 2005,A&A, 432, 189) is examined. Its applicability to observedfrequencies of rotating γ Doradus stars is discussed taking intoaccount the following aspects: the use of a perturbative approach tocompute adiabatic oscillation frequencies; the effect of rotation on theobservational Brunt-Väisälä integral determination andfinally, the problem of disentangling multiplet-like structures fromfrequency patterns due to the period spacing expected for high-ordergravity modes in asymptotic regime. This analysis reveals that the FRMproduces reliable results for objects with rotational velocities up to70 {km s-1}, for which the FRM intrinsic error increases oneorder of magnitude with respect to the typical FRM errors given in Moyaet al. (2005, A&A, 432, 189). Our computations suggest that, giventhe spherical degree ℓ identification, the FRM may be discriminatingfor m=0 modes, in the sense that the method avoids any misinterpretationinduced by the presence of rotationally split multiplet-like structures,which reinforces the robustness of the method. However, if ℓ isunknown, such discrimination is not ensured. In order to check the FRMin presence of slow-moderate rotation, we have applied it to the threeobserved frequencies of the slowly rotating ({v sin i}=29 {kms-1}) γ Doradus star HD 48501.
| Multi-site, multi-technique survey of γ Doradus candidates. I. Spectroscopic results for 59 stars
We present the first results of a 2-year high-resolution spectroscopycampaign of 59 candidate γ Doradus stars which were mainlydiscovered from the HIPPARCOS astrometric mission. More than 60% of thestars present line profile variations which can be interpreted as due topulsation related to γ Doradus stars. For all stars we alsoderived the projected rotation velocity (up to more than 200 kms-1). The amplitude ratios 2K/Δ m for the mainHIPPARCOS frequency are in the range 35-96 kms-1,mag-1. About 50% of the candidates arepossible members of binary systems, with 20 stars being confirmedγ Doradus. At least 6 stars present composite spectra, and in allbut one case (for which only one spectrum could be obtained), the narrowcomponent shows line profile variations, pointing towards anuncomfortable situation if this narrow component originates from a shellsurrounding the star. This paper is the first of a series concerningmode identification using both photometric and spectroscopic methods forthe confirmed γ Doradus stars of the present sample.Partially based on observations obtained at the Observatoire deHaute-Provence.
| Long-term multicolour photometry and high-resolution spectroscopy of the two γ Doradus stars HD 12901 and HD 48501
We gathered long-term multicolour GenevaUB1BB2V1VG photometric andhigh-resolution (R=40 000) spectroscopic data of the two γ Doradusstars HD 12901 and HD 48501. The photometry reveals three frequenciesfor each of the two stars: f1=1.21563 c d-1,f2=1.39594 c d-1 and f3=2.18636 cd-1 for HD 12901 and f1=1.09408 c d-1,f2=1.29054 c d-1 and f3=1.19924 cd-1 for HD 48501. The photometric amplitude is each timelargest in the Geneva B1 filter and the variations in all thedifferent filters are perfectly in phase within the measurement errors.Mode identification points out that the six modes are all ℓ=1 modesand that the non-adiabatic temperature variations are extremely small,in contradiction to current theoretical predictions. Our spectra showthat all the observed frequencies are intrinsic to the stars and cannotbe due to binarity. We detect clear line-profile variations at lowamplitude (<1 km s-1) due to the oscillations of bothtargets. The estimated v sin i from the spectra are 53 kms-1 for HD 12901 and 29 km s-1 for HD 48501.It is at present unclear if the triplet-like structure for HD 48501 isthe consequence of rotational splitting or of the large separationexpected for high-order gravity modes in the asymptotic regime.Based on observations gathered with the Swiss 0.7 m telescope equippedwith the photometer P 7 and with the Swiss 1.2 m Euler telescopeequipped with the spectrograph CORALIE, both situated at La Silla,Chile. Reduced data available upon request from the first author.
| The 77th Name-List of Variable Stars
We present the next regular Name-List of variable stars containinginformation on 1152 variable stars recently designated in the system ofthe General Catalogue ofVariable Stars. New designations are alsointroduced for two ``old'' variables whose corrected coordinates bringthem to other constellations.
| A Theoretical γ Doradus Instability Strip
In this paper, we present the first theoretical γ Doradusinstability strip. We find that our model instability strip agrees verywell with the previously established, observationally based, instabilitystrip of Handler & Shobbrook. We stress, as do Guzik et al., thatthe convection zone depth plays the major role in the determination ofour instability strip. Once this depth becomes too deep or too shallow,the convection zone no longer allows for pulsational instability. Ourtheoretical γ Dor instability strip is bounded by ~6850 and 7360 Kat the red and blue edge, respectively, on the zero-age main sequenceand by ~6560 and 7000 K at the red and blue edge, respectively,approximately 2 mag more luminous. This theoretical strip, transformedto the observer's color-magnitude diagram, overlays the region wheremost of the 30 bona fide γ Dor stars are found.
| A Dozen New γ Doradus Stars
We use new high-dispersion spectroscopic and precise photometricobservations to identify 12 new γ Doradus stars. Two of the 12systems are double-lined binaries that show obvious velocityvariability. Five other stars have metallic lines with compositeprofiles characterized by a narrow feature near the center of each broadcomponent. Spectrograms of the Hα line indicate that all fivestars are binaries rather than shell stars. The remaining five stars inour sample are probably single. All 12 stars are photometricallyvariable with amplitudes between 6 and 87 mmag in Johnson B and periodsbetween 0.3 and 1.2 days. Four stars are monoperiodic; the rest havebetween two and five independent periods. The variability at all periodsapproximates a sinusoid. Although many of the stars lie within theδ Scuti instability strip, none exhibit the higher frequencyvariability seen in δ Scuti stars. We have increased the sample ofknown γ Doradus stars by 40% and revised the positions of a numberof variables in the H-R diagram by accounting for duplicity. Our list of42 confirmed γ Doradus variables gives some of their properties.All are dwarfs or subgiants and lie within a well-defined region of theH-R diagram that overlaps the cool edge of the δ Scuti instabilitystrip. We compare the observed location of the γ Doradus variableswith a recently published theoretical γ Doradus instability stripand find good agreement.
| Six New γ Doradus Stars
We present high-resolution spectroscopy and precision photometry of sixnew γ Doradus stars, one of which was independently discovered byanother group. This brings the total number of confirmed γ Doradusvariables to 30. All six of these variables fall in the spectral classrange F0-F2 all but one are subgiants. The six stars have between oneand five photometric periods in the range 0.3-1.2 days. We find noevidence for higher frequency δ Scuti pulsations in any of thesesix stars. Our spectroscopic observations reveal HD 108100 to be thefirst confirmed γ Doradus variable with composite broad and narrowline profiles suggesting the presence of a circumstellar shell or disk.HD 221866 has the most asymmetric absorption lines of the six stars inthis paper and also the largest photometric amplitude. Most of the 30confirmed γ Doradus variables lie in a fairly tight region of theH-R diagram on or just above the main sequence that partially overlapsthe cool edge of the δ Scuti instability strip. However, threestars, including two of the new variables in this paper, are subgiantsthat lie well within the δ Scuti strip. Among the 30 confirmedγ Doradus variables, we find no correlation between thephotometric periods and intrinsic color, absolute magnitude, orluminosity.
| Near IR spectroscopy of active galactic nuclei
Using the VLT together with the near infrared instrument ISAAC, we haveobtained medium spectral and high spatial resolution observations of asample of nearby Seyfert galaxies in the H-band. This band isparticularly suited for stellar population studies since the stellarcomponent dominates over the AGN nucleus. The H-band also includes thepeak contribution from cool stars. The AGN spectra are very rich instrong metallic lines which are sensitive to stellar luminosity class.For 4 out of 5 galaxies the central velocity dispersions are found to besignificantly lower than reported in previous studies. Gradients in thestellar population within the central regions were searched for,together with evidence for dilution of the stellar spectral featureswithin the nucleus. Based on observations collected at the Very LargeTelescope (UT1) of the European Southern Observatory, Paranal, Chile,ESO NO 63.A-0366.
| 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
| CCD photometry and astrometry for visual double and multiple stars of the HIPPARCOS catalogue III. CCD photometry and differential astrometry for 253 southern ``intermediate'' systems
We present new astrometric and photometric data for 253 visual doublestars of the ``intermediate'' class, i.e. with angular separations inthe range 1 to 15 arcsec. The multi-colour observations were obtained in1992-94 as part of the ESO Key Programme ``Visual Double Stars''performed at La Silla Observatory (Chile). Differential magnitudes andcolours have been secured in a systematic way while component magnitudesand colour indices have been determined in the V and I passbands of theCousins standard system in good photometric conditions only. Internaland mean external errors are smaller than respectively 0.01 mag and afew hundreths of a magnitude (typically less than 0.03 mag). Relativepositions are obtained as a by-product with internal errors of the orderof 0.006 arcsec in angular separation (corresponding to pixel width x0.02) and 0.07 degr in position angle. Final accuracies are thoroughlydiscussed: we illustrate the overall excellent quality of the data andestimate the quality degradation for angular separations barely largerthan the width of the seeing disk. Based on observations made at LaSilla (ESO, Chile, Key Programme 7-009-49K).
| A search for new gamma Doradus stars in the Geneva photometric database
We present a study of selected potential gamma Doradus stars observed inthe Geneva photometric system. Eleven stars were monitored at leastduring the last year of functioning of the 70 cm Swiss telescope at LaSilla, leading to about one thousand photometric measurements andpermitting a detailed analysis of these stars. After the analysis, fivestars are thought to be constant stars. We report three new gamma Dorstars. A spectroscopic campaign has been started at La Silla with thenew 1m20 Swiss telescope, equipped with the spectrograph CORALIE, ofwhich we show the results for the selected stars.
| Radial velocities of HIPPARCOS southern B8-F2 type stars
Radial velocities have been determined for a sample of B8-F2 type starsobserved by the Hipparcos satellite. Observations were obtained withinthe framework of an ESO key-program. Radial velocities have beenmeasured using a cross-correlation method, the templates being a grid ofsynthetic spectra. The obtained precision depends on effectivetemperature and projected rotational velocity of the star as well as ona possible asymmetry of the correlation peak generally due to secondarycomponents. New spectroscopic binaries have been detected from theseasymmetries and the variability of the measured radial velocity.Simulations of binary and triple systems have been performed. Forbinaries our results have been compared with Hipparcos binary data.Adding the variable radial velocities, the minimum binary fraction hasbeen found 60% for physical systems. Radial velocities have beendetermined for 581 B8-F2 stars, 159 being new. Taking into accountpublished radial velocities, 39% south A-type stars with V magnitudelower than 7.5 have a radial velocity. Based on observations obtained atthe European Southern Observatory (ESO, La Silla, Chile) and on datafrom the ESA Hipparcos astrometry satellite.}\fnmsep \thanks{Tables 7, 8and 9 are only available in electronic form at the CDS via anonymous ftpto 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
| An extensive Delta a-photometric survey of southern B and A type bright stars
Photoelectric photometry of 803 southern BS objects in the Deltaa-system as detection tool for magnetic chemically peculiar (=CP2) starshas been carried out and compared to published spectral types. Thestatistical yield of such objects detected by both techniques ispractically the same. We show that there are several factors whichcontaminate the search for these stars, but this contamination is onlyof the order of 10% in both techniques. We find a smooth transition fromnormal to peculiar stars. Our sample exhibits the largest fraction ofCP2 stars at their bluest colour interval, i.e. 10% of all stars in thecolour range -0.19 <= B-V < -0.10 or -0.10 <= b-y < -0.05.No peculiar stars based on the Delta a-criterion were found at bluercolours. Towards the red side the fraction of CP2 stars drops to about3% for positive values of B-V or b-y with red limits roughlycorresponding to normal stars of spectral type A5. The photometricbehaviour of other peculiar stars: Am, HgMn, delta Del, lambda Boo, Heabnormal stars, as well as Be/shell stars and supergiants shows someslight, but definite deviations from normal stars. Spectroscopic andvisual binaries are not distinguished from normal stars in their Delta abehaviour. The results of this work justify larger statistical work(e.g. in open clusters) employing more time-saving photometric methods(CCD). \newpage Based on observations obtained at the European SouthernObservatory, La Silla, Chile. This research has made use of the Simbaddatabase, operated at CDS, Strasbourg, France. Table 2 is only availablein electronic form via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| 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
| 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
| A catalogue of Fe/H determinations - 1991 edition
A revised version of the catalog of Fe/H determinations published by G.Cayrel et al. (1985) is presented. The catalog contains 3252 Fe/Hdeterminations for 1676 stars. The literature is complete up to December1990. The catalog includes only Fe/H determinations obtained from highresolution spectroscopic observations based on detailed spectroscopicanalyses, most of them carried out with model atmospheres. The catalogcontains a good number of Fe/H determinations for stars from open andglobular clusters and for some supergiants in the Magellanic Clouds.
| A second list of wide visual binaries
Not Available
| A second list of wide visual binaries
Not Available
| Lithium in F stars of known age
High resolution spectra of 25 F stars in visual binary systems wereobtained with the Canada-France-Hawaii Telescope in a search for acorrelation between Li abundance and the age of F stars. Computerizedscans were made for equivalent widths of the Li 6707 A resonance, the CaI 6717 A line and five neighboring Fe I lines. Stars cooler than 6300 Kexhibited an order of magnitude spread in Li abundance, symptomatic ofage-dependent depletion of Li in late F and early G stars. Li wasdepleted by factors of 6-20 in stars with temperatures from 6300-6700 K,a depletion/temperature pattern also seen in Hyades and mid-F stars, andwhich may be affected by the presence of companion objects.
| A sample of solar-type stars of known age
A sample of field F and G dwarfs of known ages is presented. All thedwarfs are secondaries of visual binaries in which the temperature andgravity of the hotter primary has been estimated from Stromgrenphotometry, and its age derived from reference to isochrones. This ageis taken to apply to the secondary. Even in the case of F-typesecondaries, which themselves have measured Stromgren indices, it ismuch better to estimate ages from the primaries as it is demonstratedthat use of isochrones to determine age of stars not far evolved fromthe main sequence can lead to significant systematic overestimates ofages when the photometric measurements have typical random errors. Anumber of systems in which photometry is available for both componentshave primaries which appear much younger than the secondaries,suggesting a need for further investigation.
| Ages and uvbybeta photometry of wide visual binaries. II
Visual magnitudes and color indices b-y, m1, c1 and beta have beenobtained for the members of 39 double or multiple systems containingstars with magnitudes greater than 4m. Relationships between stellarages, spectral types and photometric indices are given from a sample ofabout 3,500 stars. Data is presented with regard to MK spectral types,the separation, and absolute magnitudes; also tabulated are the meanvalues of photometric unreddened indices with their standard deviationfor intervals of 0.2 in log age. From calculations for each binary ofthe relative difference in the ages of the components and the differencein the effective temperatures, an increase in the relative differencesin ages with the differences in temperatures is noted.
| Photographic measures of double stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..357T&db_key=AST
| Photovisual differences in magnitudes of 331 mainly southern double stars
Not Available
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