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λ Bootis stars with composite spectra
We examine the large sample of λ Boo candidates collected inTable 1 of Gerbaldi et al. (\cite{Gerbaldi2003}) to see how many of themshow composite spectra. Of the 132 λ Boo candidates we identify22 which definitely show composite spectra and 15 more for which thereare good reasons to suspect a composite spectrum. The percentage ofλ Boo candidates with composite spectra is therefore >17% andpossibly considerably higher. For such stars the λ Booclassification should be reconsidered taking into account the fact thattheir spectra are composite. We argue that some of the underabundancesreported in the literature may simply be the result of the failure toconsider the composite nature of the spectra. This leads to thelegitimate suspicion that some, if not all, the λ Boo candidatesare not chemically peculiar at all. A thorough analysis of even a singleone of the λ Boo candidates with composite spectra, in which thecomposite nature of the spectrum is duly considered, which woulddemonstrate that the chemical peculiarities persist, would clear thedoubt we presently have that the stars with composite spectra may not beλ Boo stars at all.Based on observations collected at ESO (Echelec spectrograph) and at TBL(Telescope Bernard Lyot) of the Pic du Midi Observatory (France).
| The heterogeneous class of lambda Bootis stars
We demonstrate that it is arduous to define the lambda Boo stars as aclass of objects exhibiting uniform abundance peculiarities which wouldbe generated by a mechanism altering the structure of their atmosphericlayers. We collected the stars classified as lambda Boo up to now anddiscuss their properties, in particular the important percentage ofconfirmed binaries producing composite spectra (including our adaptiveoptics observations) and of misclassified objects. The unexplained RVvariables (and thus suspected binaries), the known SB for which we lackinformation on the companion, the stars with an UV flux inconsistentwith their classification, and the fast rotating stars for which noaccurate abundance analysis can be performed, are also reviewed.Partly based on observations collected at the CFH Telescope (Hawaii) andat TBL of the Pic du Midi Observatory (France).Table \ref{tab5} is only available in electronic form athttp://www.edpsciences.org
| On the Period-Luminosity-Colour-Metallicity relation and the pulsational characteristics of lambda Bootis type stars
Generally, chemical peculiarity found for stars on the upper mainsequence excludes delta Scuti type pulsation (e.g. Ap and Am stars), butfor the group of lambda Bootis stars it is just the opposite. This makesthem very interesting for asteroseismological investigations. The groupof lambda Bootis type stars comprises late B- to early F-type,Population I objects which are basically metal weak, in particular theFe group elements, but with the clear exception of C, N, O and S. Thepresent work is a continuation of the studies by Paunzen et al.(\cite{Pau97}, \cite{Pau98}), who presented first results on thepulsational characteristics of the lambda Bootis stars. Since then, wehave observed 22 additional objects; we found eight new pulsators andconfirmed another one. Furthermore, new spectroscopic data (Paunzen\cite{Pau01}) allowed us to sort out misidentified candidates and to addtrue members to the group. From 67 members of this group, only two arenot photometrically investigated yet which makes our analysis highlyrepresentative. We have compared our results on the pulsationalbehaviour of the lambda Bootis stars with those of a sample of deltaScuti type objects. We find that at least 70% of all lambda Bootis typestars inside the classical instability strip pulsate, and they do sowith high overtone modes (Q < 0.020 d). Only a few stars, if any,pulsate in the fundamental mode. Our photometric results are inexcellent agreement with the spectroscopic work on high-degree nonradialpulsations by Bohlender et al. (\cite{Boh99}). Compared to the deltaScuti stars, the cool and hot borders of the instability strip of thelambda Bootis stars are shifted by about 25 mmag, towards smaller(b-y)_0. Using published abundances and the metallicity sensitiveindices of the Geneva 7-colour and Strömgren uvbybeta systems, wehave derived [Z] values which describe the surface abundance of theheavier elements for the group members. We find that thePeriod-Luminosity-Colour relation for the group of lambda Bootis starsis within the errors identical with that of the normal delta Scutistars. No clear evidence for a statistically significant metallicityterm was detected. Based on observations from the Austrian AutomaticPhotoelectric Telescope (Fairborn Observatory), SAAO and Siding SpringObservatory.
| The abundance pattern of lambda Bootis stars
Within a project to investigate the properties of lambda Bootis stars,we report on their abundance pattern. High resolution spectra have beenobtained for a total of twelve candidate lambda Bootis stars, four ofthem being contained in spectroscopic binary systems, and detailedabundance analyses have been performed. All program stars show acharacteristic lambda Bootis abundance pattern (deficient heavy elementsand solar abundant light elements) and an enhanced abundance of Na. Thiswork raises the fraction of lambda Bootis stars with known abundances to50%. The resulting abundances complemented by literature data are usedto construct a ``mean lambda Bootis abundance pattern'', which exhibits,apart from general underabundances of heavy elements (~-1 dex) and solarabundances of C, N, O, Na and S, a star-to-star scatter which is up totwice as large as for a comparable sample of normal stars. Based onobservations obtained at the Osservatorio Astronomico di Padua-Asiago,OPD/LNA, KPNO and DSO.
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Paper I of this series presented precise MK spectral types for 372 lateA-, F-, and early G-type stars with the aim of understanding the natureof luminosity classification on the MK spectral classification systemfor this range of spectral types. In this paper, a multidimensionaldownhill simplex technique is introduced to determine the basicparameters of the program stars from fits of synthetic spectra andfluxes with observed spectra and fluxes from Strömgren uvbyphotometry. This exercise yields useful calibrations of the MK spectralclassification system but, most importantly, gives insight into thephysical nature of luminosity classification on the MK spectralclassification system. In particular, we find that in this range ofspectral types, microturbulence appears to be at least as important asgravity in determining the MK luminosity type.
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars
This is the first in a series of two papers that address the problem ofthe physical nature of luminosity classification in the late A-, F-, andearly G-type stars. In this paper, we present precise spectralclassifications of 372 stars on the MK system. For those stars in theset with Strömgren uvbyβ photometry, we derive reddenings andpresent a calibration of MK temperature types in terms of the intrinsicStrömgren (b-y)0 index. We also examine the relationshipbetween the luminosity class and the Strömgren c1 index,which measures the Balmer jump. The second paper will address thederivation of the physical parameters of these stars, and therelationships between these physical parameters and the luminosityclass. Stars classified in this paper include one new λ Bootisstar and 10 of the F- and G-type dwarfs with recently discoveredplanets.
| Light element non-LTE abundances of lambda Bootis stars. II. Nitrogen and sulphur
One of the main characteristics proclaimed for the group of the lambdaBootis stars is the apparent solar abundance of the light elements C, N,O and S. The typical abundance pattern is completed by the strongunderabundances of the Fe-peak elements. In the first paper of thisseries, we have shown that carbon is less abundant than oxygen but bothelements are still significantly more abundant than Fe-peak elements.The mean abundances, based on a detailed non-LTE investigation, werefound -0.37 dex and -0.07 dex, respectively. As a further step, we nowpresent non-LTE abundances of nitrogen and sulphur for thirteen membersof the lambda Bootis group based on several spectral lines between 8590Å, and 8750 Å. Furthermore, LTE abundances for calcium inthe same spectral range were derived and compared with values from theliterature. Similar to the mean abundances of carbon and oxygen, nearlysolar values were found (-0.30 dex for nitrogen and -0.11 dex forsulphur) for our sample of program stars. Among our sample, onepreviously undetected binary system (HD 64491) was identified. From astatistical point of view, the abundances of the light elements rangefrom slightly overabundant to moderately underabundant compared to theSun. However, the individual objects always exhibit a similiar pattern,with the Fe-peak elements being significantly more underabundant thanthe light elements. No correlation of the derived abundances withastrophysical parameters such as the effective temperature, surfacegravity or projected rotational velocity was found. Furthermore, theabundances of the light elements do not allow us to discriminate betweenany proposed theory. Based on observations obtained at BNAO Rozhen andComplejo Astronómico el Leoncito (CASLEO), operated under theagreement between the Consejo Nacional de InvestigacionesCientíficas y Técnicas de la República Argentinaand the National Universities of La Plata, Córdoba y San Juan.
| 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).
| 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
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Accurate LTE abundances of seven well established lambda Bootis stars
High resolution and high signal-to-noise CCD spectra were analyzed todetermine accurate LTE abundances for seven well established {lambdaBootis} stars (a group of A to F-type stars with strong underabundancesof Fe-peak elements whereas the C, N, O and S appear to be solarabundant): HD 31295, HD 125162, HD 142994, HD 149303, HD 192640, HD204041 and HD 221756. In general, 13 elements were investigated. Theeffective temperatures of our program stars range from 7200 to 9000 K.The main results are the following: C, O, Na and S seem to be nearlysolar abundant for all investigated stars. A wide range ofunderabundances within the individual stars exists for all otherelements. No correlation of the individual abundances with astrophysicalparameters such as T_eff, log g and v sin i was found. These results areconsistent with the accretion/diffusion model which is currently adoptedfor the explanation of the {lambda Bootis} phenomenon. Based onobservations from the Special Astrophysical Observatory of the RussianAcademy of Sciences, Russia, Northern Caucasus and the McDonaldObservatory
| How many lambda Bootis stars are binaries?
In the attempt to shed new light on the lambda Boo phenomenon weanalyzed the astrometric, photometric and spectroscopic characteristicsof stars out of a list of recently selected lambda Boo candidates. Weshow that the class is still ill-defined and discuss the possibilitythat some, if not most stars presently classified as lambda Boo, are infact binary pairs and that peculiar abundances may not correspond toactual values if the average values of the atmospheric parameters{Teff} and log g are assumed and the effect of veiling is nottaken into account. Partly based on data from the ESA Hipparcosastrometry satellite.
| Light element non-LTE abundances of lambda Bootis stars. I. Carbon and oxygen
Abundances for the light elements of {lambda Bootis} stars are a mainkey to understand the astrophysical processes behind the so-called{lambda Bootis} phenomenon. These stars are characterized by a typicalabundance pattern (strong underabundances of the Fe-peak elementswhereas the light elements have apparently solar abundances) which isstill based mainly on LTE-calculations. Therefore we started aninvestigation to derive accurate abundances of the light elements (C, N,O and S). For this purpose a new oxygen model atom was implemented inthe Kiel non-LTE code. High resolution and high signal-to-noise spectrawere used. For each element only a single wavelength region with linesof the specific element was selected and observed in order to avoidcontamination from other elements. In the first paper we presentabundances for carbon and oxygen of a statistically significant numberof well established {lambda Bootis} stars. The second paper will dealwith nitrogen and sulphur. The most important result is that on averagecarbon is less abundant than oxygen but still both elements aresignificant more abundant than the Fe-peak elements. Furthermore theanticorrelation of carbon and oxygen with the silicon abundance isproven, which strongly supports the accretion/diffusion theory. Based onobservations obtained at ESO-La\,Silla and BNAO Rozhen
| 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
| Pulsation in lambda Bootis stars
In this paper we present a further step in applying asteroseismictechniques to the group of lambda Bootis stars which can becharacterized as nonmagnetic A to F-type Population I dwarfs withsignificant (surface) underabundances of Fe-peak elements. Since noconclusive theory explaining the origin of the observed abundanceanomalies exists, an extensive photometric survey for pulsation in thisgroup has been initiated. Knowledge about the pulsational properties(most members are located within the classical instability strip) couldhelp to establish constrains about the overall abundance of these starsas well as on the evolutionary status. New photometric observations werecarried out for eleven stars. Variability was detected in four stars(e.g. lambda Bootis itself) whereas the remaining seven objects areprobably constant. In total, 52 members of this group have beenphotometrically investigated so far. With 22 pulsating and 30``constant'' stars, we derive a ratio of at least 50 % for variable tononvariable members inside the classical instability strip. This resultis based on high quality Hipparcos and new photometric data. Theobserved log /lineρ//lineρ_ȯ and log P values for thepulsating members are compatible with standard (solar abundant) deltaScuti models supporting the hypothesis that the found abundanceanomalies are restricted to the surface only. Otherwise the pulsationalproperties of this group are not outstanding compared to ``normal''delta Scuti stars, indicating that the mechanism driving the pulsationsis very similar. Based on observations obtained at ESO-La\,Silla, CTIO,SAAO, McDonald Observatory, Instituto Astrofisica Andalucia Observatoryand with the Hipparcos satellite
| Identification of lambda Bootis stars using IUE spectra. I. Low resolution data
An analysis of the stars included in the catalogue of lambda Bootisstars by Paunzen et al. (1997) and which also have IUE observations ispresented here. Population I A-F type stars as well as field horizontalbranch stars were also included in the analysis. Using line-ratios ofcarbon to heavier elements (Al and Ni) allows us to establishunambiguous membership criteria for the lambda Bootis group. Tables 1-3are only available in electronic form at CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| A spectroscopic survey for lambda Bootis stars. I. Strategy, techniques and first results
In recent years, the chemically peculiar (CP) stars of the upper mainsequence have become a fruitful field for the testing of astrophysicaltheories. Processes such as diffusion, convection and mass loss havebeen developed theoretically and introduced into models. The group oflambda Bootis stars, however, is remarkable among the chemicallypeculiar stars as they are nonmagnetic, Population I, A to F-type dwarfswhich show significant underabundances of metals (except for C, N, O andS). Unfortunately, the small number of confirmed members of the lambdaBootis class makes a sound statistical analysis of their propertiesimpossible. Thus, it is still difficult to decide between the twotheories - mass loss with diffusion and the accretion theory - whichhave been proposed to explain the origin of these stars. We thereforehave started a spectroscopic survey to find new lambda Bootis stars inthe field as well as in open clusters and associations. The presence oflambda Bootis stars in open clusters and associations would permit adetermination of the ages of these stars, and thus would yield animportant test for distinguishing between the two theories. In thispaper we describe the selection of candidates using photometriccriteria, the basic requirements, spectroscopic follow-up observationsand results from the first three observing runs. Special care was takento avoid misclassification of our programme stars (e.g. lambda Bootisstars are often confused with intermediate Population II, He-weak orhigh v sin i stars), using a refined MK system. The discovery of atleast six new lambda Bootis stars (including three in the Orion OB1association) shows the efficacy of our selection criteria. Based onobservations obtained at the Observatoire de Haute-Provence and the DarkSky Observatory.
| Nonvariability among lambda Bootis stars
With asteroseismic techniques it is possible to investigate the interiorand the evolutionary status of stars via their frequency spectrum. Bothinformation would be very much needed for lambda Bootis stars, a groupof metal-poor Population I, A-type stars, since no conclusive theoryexists explaining the observed abundance anomalies. Geneva and Stromgrenphotometry place these stars inside the classical instability strip orat least very close to it. We therefore have started an extensivephotometric survey for pulsation in lambda Bootis stars and havediscovered so far 13 new variables. In this paper we present results forstars which presumably are constant, because we are able to establishonly an upper level for possible variability. A typical noise level of 3mmag for Stromgren b was achieved in the relevant frequency domain up to100 d^{-1}. Considering the given noise level of our survey, we concludethat at least 50% of all investigated lambda Bootis stars inside theinstability strip are pulsating, making this group remarkable comparedto stars with similar spectral types. This may suggest that a low(surface) metallicity has an influence on the pulsation Based onobservations obtained at ESO-La Silla, CTIO, SAAO, McDonald Observatory,Instituto Astrofisica Andalucia Observatory.
| A consolidated catalogue of lambda Bootis stars
lambda Bootis stars challenge our understanding of diffusion andaccretion processes related to stars and their circumstellarenvironment, and they are interesting components of the classicalinstability strip. Attempts to derive group properties with statisticalmethods are severely limited by the small number of unambiguouslyidentified lambda Bootis stars. In general, the subject appears to beobscured by incorrect memberships and it is therefore essential toprovide a sufficiently large catalogue of definitive group membersbefore modeling the lambda Bootis phenomenon. This paper describes thefirst steps towards this goal, based on our current knowledge of wellinvestigated members, leading to a concise definition of lambda Bootisstars: {Pop I hydrogen burning metal poor (except of C,N,O and S) A-typestars.} The definition does not depend on phenomenological features,like flux depressions, colour excesses, v sin i values, etc. Based on anew homogeneous catalogue with 45 lambda Bootis stars, we discussclassification criteria which can be used for a spectroscopic andphotometric all-sky survey for lambda Bootis stars in the field and inclusters of different ages. Based on observations obtained atESO-La,Silla, CTIO, Observatoire de Haute-Provence, OsservatorioAstronomico di Padua-Asiago, Univ. Toronto Southern Observatory,Observatorio do Pico dos Dias-LNA/CNPq/MCT (Brazil). Table 1 is alsoavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
| On the evolutionary status of λ Bootis stars using HIPPARCOS data.
We have used the Hipparcos data to derive absolute magnitudes and thusthe evolutionary status for the group of λ Bootis stars. Theorigin for this small group of nonmagnetic, chemically peculiar stars,still remains a matter of debate. Using new evolutionary tracks, we areable to provide an age determination to distinguish between the twoproposed theories - the diffusion/mass-loss and the accretion theory.Our results establish the member of this group as objects which are veryclose to the Main Sequence. This is also supported by Pre-Main Sequenceevolutionary tracks as well as by observational results. We thereforecontradict prior conclusions that most of these stars are in the middleof their Main Sequence lifetime. The new results strongly support thepredictions of the accretion theory.
| Nonvariability among lambda Bootis Stars III.: CTIO (1995) and McDonald (1995) Data
Not Available
| 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.
| Accretion from Circumstellar Discs and the Lambda-Bootis Phenomenon
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.269..209K&db_key=AST
| The correction in right ascension of 508 stars determinated with PMO photoelectric transit instrument.
Not Available
| UBV photometry of stars whose positions are accurately known. VI
Results are presented from UBV photometric observations of 1000 stars ofthe Bright Star Catalogue and the faint extension of the FK5.Observations were carried out between July 1987 and December 1990 withthe 40-cm Cassegrain telescope of the Kvistaberg Observatory.
| Catalogue of Lambda Bootis Candidates
Not Available
| Third preliminary catalogue of stars observed with the photoelectric astrolabe of the Beijing Astronomical Observatory.
Not Available
| 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.
| Narrow-band photometry of late-type stars. II
This paper presents extensive narrow-band photometry in the Uppsalasystem supplementing earlier published mesurements so that data now areavailable for all late-type stars brighter than V = 6.05 and a number ofgalactic cluster members. Numerous UBV and BV measurements are alsopublished. The data are used to determine relations for the predictionof UBV intrinsic colors for late-type stars from the narrow-bandmeasurements. The main purpose of the data is to constitute the basisfor the determination of solar-neighborhood space densities of late-typestars, mainly giants of different kinds; these space densities will becombined with narrow-band data for fainter stars in the north Galacticpole region to yield the decrease of space density with distance fromthe galactic plane for many kinds of late-type stars.
| Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
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Membro dei seguenti gruppi:
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Osservazione e dati astrometrici
| Costellazione: | Ercole |
| Ascensione retta: | 16h31m47.30s |
| Declinazione: | +45°35'54.0" |
| Magnitudine apparente: | 5.65 |
| Distanza: | 69.061 parsec |
| Moto proprio RA: | -7.3 |
| Moto proprio Dec: | 35.9 |
| B-T magnitude: | 5.808 |
| V-T magnitude: | 5.686 |
Cataloghi e designazioni:
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