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Beyond the big Galaxy: the structure of the stellar system 1900 - 1952
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| R Scuti nach der Jahrtausendwende.
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| Survey for Transiting Extrasolar Planets in Stellar Systems. IV. Variables in the Field of NGC 1245
The Survey for Transiting Extrasolar Planets in Stellar Systems (STEPSS)project is a search for planetary transits in open clusters. In thispaper we analyze the STEPSS observations of the open cluster NGC 1245 todetermine the variable-star content of the cluster. Out of 6787 starsobserved with V<22, of which ~870 are cluster members, we find 14stars with clear intrinsic variability that are potential clustermembers and 29 clear variables that are not cluster members. None ofthese variables have been previously identified. We present lightcurves, finder charts, and stellar/photometric data on these variableobjects. Several of the interacting binaries have estimated distancesconsistent with the cluster distance determined from isochrone fits tothe color-magnitude diagram. Four stars at the main-sequence turnoff ofthe cluster have light curves consistent with γ Doradusvariability. If these γ Doradus candidates are confirmed, theyrepresent the oldest and coolest members of this class of variablediscovered to date.
| Manganese Abundances in Cluster and Field Stars
We have derived Mn abundances for more than 200 stars in 19 globularclusters. In addition, Mn abundance determinations have been made for acomparable number of halo field and disk stars possessing an overlappingrange of metallicities and stellar parameters. Our primary data set wascomprised of high-resolution spectra previously acquired at theMcDonald, Lick, and Keck Observatories. To enlarge our data pool, weacquired globular and open cluster spectra from several otherinvestigators. Data were analyzed using synthetic spectra of the 6000Å Mn I triplet. Hyperfine structure parameters were included inthe synthetic spectra computations. Our analysis shows that for themetallicity range -0.7>[Fe/H]>-2.7, stars of 19 globular clustershave a mean relative abundance of <[Mn/Fe]>=-0.37+/-0.01(σ=0.10), a value in agreement with that of the field stars,<[Mn/Fe]>=-0.36+/-0.01 (σ=0.08). Despite the 2 orders ofmagnitude span in metallicity, the <[Mn/Fe]> ratio remainsconstant in both stellar populations. Our Mn abundance data indicatethat there is no appreciable variation in the relative nucleosyntheticcontribution from massive stars that undergo core-collapse supernovaeand thus no significant change of the associated initial mass functionin the specified metallicity range.
| Chemical Homogeneity in the Hyades
We present an abundance analysis of the heavy elements Zr, Ba, La, Ce,and Nd for Hyades F-K dwarfs based on high-resolution, highsignal-to-noise ratio spectra from Keck HIRES. The derived abundancesshow the stellar members to be highly uniform, although some elementsshow a small residual trend with temperature. The rms scatter for eachelement for the cluster members is as follows: Zr=0.055, Ba=0.049,Ce=0.025, La=0.025, and Nd=0.032 dex. This is consistent with themeasurement errors and implies that there is little or no intrinsicscatter among the Hyades members. Several stars thought to be nonmembersof the cluster based on their kinematics are found to deviate from thecluster mean abundances by about 2 σ. Establishing chemicalhomogeneity in open clusters is the primary requirement for theviability of chemically tagging Galactic disk stars to common formationsites in order to unravel the dissipative history of early diskformation.
| Washington photometry of open cluster giants: two moderately metal-poor anticentre clusters
New photometric data in the Washington system are presented for redgiant candidates in NGC 1817 and 2251, two open clusters located towardsthe Galactic anticentre direction. In the case of NGC 2251, theWashington data are supplemented with new UBV and David DunlapObservatory (DDO) photoelectric photometry. Published radial velocitiesare used to separate field stars from cluster giants. The photometricdata yield an effective temperature and metal abundance for each clustermember. Five independent Washington abundance indices yield meanmetallicities of [Fe/H]= 0.25 +/- 0.04 for NGC 1817 and 2251,respectively. From combined BV and DDO data, we also derive E(B-V) =0.21 +/- 0.03 and [Fe/H]DDO=-0.14 +/- 0.05 for NGC 2251. Bothobjects are then found to be on the metal-poor side of the distributionof open clusters, their metallicities being compatible with theexistence of a radial abundance gradient in the disc. Using the WEBDAOpen Cluster data base and the available literature, we re-examined theoverall properties of a sample of 30 clusters located towards theGalactic anticentre with the distances, ages and metallicitiesavailable. This cluster sample presents no evidence of an abundancegradient perpendicular to the Galactic plane, nor is an age-metallicityrelation found. However, a radial abundance gradient of -0.093 dexkpc-1 is derived over a Galactocentric distance of 14 kpc, agradient which is in keeping with most recent determinations. This valuepractically does not change when all clusters with basic parametersknown up to this date are considered.
| Caroline Herschel as observer
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| Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11
This work presents the first large-scale photometric variability surveyof the intermediate-age (~200 Myr) open cluster M11. Thirteen nights ofdata over two observing seasons were analyzed (using crowded field andensemble photometry techniques) to obtain high relative precisionphotometry. In this study we focus on the detection of candidate membervariable stars for follow-up studies. A total of 39 variable stars weredetected and can be categorized as follows: one irregular (probablypulsating) variable, six δ Scuti variables, 14 detached eclipsingbinary systems, 17 W UMa variables, and one unidentified/candidatevariable. While previous proper-motion studies allow for clustermembership determination for the brightest stars, we find thatmembership determination is significantly hampered below V=15, R=15.5 bythe large population of field stars overlapping the cluster mainsequence. Of the brightest detected variables that have a highlikelihood of cluster membership, we find five systems in which furtherwork could help constrain theoretical stellar models, including onepotential W UMa member of this young cluster.
| Survey for Transiting Extrasolar Planets in Stellar Systems. II. Spectrophotometry and Metallicities of Open Clusters
We present metallicity estimates for seven open clusters based onspectrophotometric indices from moderate-resolution spectroscopy.Observations of field giants of known metallicity provide a correlationbetween the spectroscopic indices and the metallicity of open clustergiants. We use χ2 analysis to fit the relation ofspectrophotometric indices to metallicity in field giants. The resultingfunction allows an estimate of the target-cluster giants' metallicitieswith an error in the method of +/-0.08 dex. We derive the followingmetallicities for the seven open clusters: NGC 1245, [M/H]=-0.14+/-0.04NGC 2099, [M/H]=+0.05+/-0.05 NGC 2324, [M/H]=-0.06+/-0.04 NGC 2539,[M/H]=-0.04+/-0.03 NGC 2682 (M67), [M/H]=-0.05+/-0.02 NGC 6705,[M/H]=+0.14+/-0.08 NGC 6819, [M/H]=-0.07+/-0.12. These metallicityestimates will be useful in planning future extrasolar planet transitsearches, since planets may form more readily in metal-richenvironments.
| Structure and stellar content analysis of the open cluster M 11 with 2MASS photometry
An overall analysis of the structure and stellar content of M 11 ispresented, thanks to the wide-angle 2MASS spatial coverage. We derivephotometric and structural parameters and discuss the spatial dependanceof the luminosity and mass functions. Photometric parameters basicallyagree with previous ones mostly based on the optical. We obtained a coreradius of 1.23 pc and a tidal radius of 29 pc. In particular, thecluster is populous enough so that the tidal radius could be obtained byfitting the three-parameter King profile to the radial distribution ofstars. We analyzed the spatial distribution of mass functions, findingthat the slope changes from -0.73 in the core to +2.88 in the outerhalo. The spatial distribution of mass function slopes derived from2MASS agrees with that derived from optical CCD data, which furtherconfirms the reliability of 2MASS data for future analyses of this kindat comparable observational limits. We detect mass segregation up todistances from the center of ≈20 arcmin. We emphasize that the massfunction slope in the core is flatter than anywhere else as aconsequence of mass segregation. The derived total cluster mass is≈11 000 M_ȯ.
| Astrophysical parameters of Galactic open clusters
We present a catalogue of astrophysical data for 520 Galactic openclusters. These are the clusters for which at least three most probablemembers (18 on average) could be identified in the ASCC-2.5, a catalogueof stars based on the Tycho-2 observations from the Hipparcos mission.We applied homogeneous methods and algorithms to determine angular sizesof cluster cores and coronae, heliocentric distances, mean propermotions, mean radial velocities, and ages. For the first time we derivedistances for 200 clusters, radial velocities for 94 clusters, and agesof 196 clusters. This homogeneous new parameter set is compared withearlier determinations, where we find, in particular, that the angularsizes were systematically underestimated in the literature.
| Abundance Trends of Alpha and Fe-Peak Elements in Globular Clusters
A fairly large fraction of Galactic globular clusters have beensubjected to some sort of high spectral resolution abundance analysis inthe past two decades. Several clusters have enjoyed the scrutiny oflarge numbers (>20) of their giant stars at very high resolution (R> 40,000) and signal-to-noise (>100), and such investigations haveeven begun to probe the fainter subgiant cluster members. Other clustershave seemed to be of lesser interest, having only studies of a few oftheir brighter members reported in the literature. This brief overviewwill consider the abundance trends of some key element groups, includingthe alpha, Fe-peak, neutron-capture, and proton-capture elements. Somecomparison with field stars will be attempted to illustrate wherestellar population differences between clusters and the field seem tooccur. Suggestions for renewed observational attention will be drawn tospecific clusters whose chemical origin appears to be substantiallydifferent than the general Galactic halo.
| Abundance Variations Within Globular Clusters
Abundance variations within globular clusters (GCs), and of GC starswith respect to field stars, are important diagnostics of a variety ofphysical phenomena, related to the evolution of individual stars, masstransfer in binary systems, and chemical evolution in high densityenvironments. The broad astrophysical implications of GCs as buildingblocks of our knowledge of the Universe make a full understanding oftheir history and evolution basic in a variety of astrophysical fields.We review the current status of the research in this field, comparingthe abundances in GCs with those obtained for field stars, discussing indepth the evidence for H-burning at high temperatures in GC stars,describing the process of self-enrichment in GCs with particularreference to the case of the most massive Galactic GC ( Cen), anddiscussing various classes of cluster stars with abundance anomalies.Whereas the overall pattern might appear very complex at first sight,exciting new scenarios are opening where the interplay between GCdynamical and chemical properties are closely linked with each other.
| The Initial Mass Function and Stellar Content of NGC 3603
We present UBVRI and Hα photometry of the extremely compact,starburst cluster NGC 3603. Ground-based images, Hubble Space Telescope(HST) archival data, as well as Chandra X-ray data have been used forthis study. We present, for the first time, optical color-magnitudediagrams (CMDs) for the stars in the cluster core down to V=22 mag. Awell-defined main sequence (MS) as well as low-mass pre-main-sequence(PMS) stars can clearly be seen in the CMDs. This result confirms thefinding by Eisenhauer et al. that low-mass stars are forming in thestarburst cluster. We also derive an age (1+/-1 Myr) and distance of thecluster (V0-MV=14.2+/-0.2 mag, i.e., d=6.9+/-0.6kpc). The interstellar reddening shows a minimum value [E(B-V)=1.25 mag]at the core (r<=0.2′) and increases rapidly up to E(B-V)~1.8mag or even higher with increasing distance from the center, whichsuggests the presence of a wind-driven cavity near the cluster center asfound by Frogel et al. and Clayton. We also determine the radius of thecluster (r~2') from the surface-density profile of bright stars andX-ray sources. To investigate the initial mass function (IMF) of thecluster, we performed a completeness test for the core region. Using thetheoretical mass-luminosity relation of MS as well as PMS stars, wederived the IMF of stars imaged with the HST/PC1. The surface density ofstars in the core is enormously high and decreases gradually withincreasing distance from the center. The slope of the IMF also showsradial variation: fairly flat in the core (Γ=-0.5+/-0.1 atr<=0.1′) and gradually steepening (Γ=-0.8+/-0.2 atr=0.1′~0.2′ and Γ=-1.2+/-0.2 at r>0.2′ ofHST/PC1). The stars in the halo region of NGC 3603 (outside of HST/PC1)seem to be slightly older (age~5 Myr) and presumably formed before thestars in the core.
| The Chemical Enrichment History of the Fornax Dwarf Spheroidal Galaxy from the Infrared Calcium Triplet
Near-infrared spectra were obtained for 117 red giants in the Fornaxdwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in orderto study the metallicity distribution of the stars and to lift theage-metallicity degeneracy of the red giant branch (RGB) in thecolor-magnitude diagram (CMD). Metallicities are derived from theequivalent widths of the infrared calcium triplet lines at 8498, 8542,and 8662 Å, calibrated with data from globular clusters, the opencluster M67, and the LMC. For a substantial portion of the sample, thestrength of the calcium triplet is unexpectedly high, clearly indicatingthat the main stellar population of Fornax is significantly moremetal-rich than could be inferred from the position of its RGB in theCMD. We show that the relative narrowness of the RGB in Fornax is causedby the superposition of stars of very different ages and metallicities.The region of parameter space occupied by the most metal-rich red giantsin Fornax-young, metal-rich, and luminous-is not covered by any of thecalibrating clusters, which introduces uncertainty in the high end ofthe metallicity scale. Using published theoretical calculations of Ca IItriplet equivalent widths, we have investigated their sensitivity toluminosity, age, and metallicity. The correlation between absolute Imagnitude and Ca II strength appears to be only slightly affected by agevariations, and we have used it to estimate the metallicities of theFornax stars. The metallicity distribution in Fornax is centered at[Fe/H]=-0.9, with a metal-poor tail extending to [Fe/H]~=-2. While thedistribution to higher metallicities is less well determined by ourobservations, the comparison with LMC data indicates that it extends to[Fe/H]~-0.4. By comparing the metallicities of the stars with theirpositions in the CMD, we have derived the complex age-metallicityrelation of Fornax. In the first few gigayears, the metal abundance roseto [Fe/H]~-1.0 dex. The enrichment accelerated in the past ~1-4 Gyr toreach [Fe/H]~-0.4 dex. More than half the sample is constituted of starsyounger than ~4 Gyr, thus indicating sustained recent star formation inFornax. These results are briefly compared with the theoreticalpredictions on the evolution of dwarf galaxies. They indicate that thecapacity of dwarf spheroidal galaxies to retain the heavy elements thatthey produce is larger than expected.Based on observations collected with the FORS1 instrument on at theEuropean Southern Observatory, Paranal, Chile (ESO 64.N-0421A).
| The Search for Variable Stars in the Open Cluster M11
We present the first large-scale variability survey of the intermediateage (app. 200 Myr) open cluster M11 (NGC 6705, C 1848-063). Nearly 9,000stars were observed for 16 nights (over two observing seasons) using the1 m telescope at the Mount Laguna Observatory. Analysis was peformedusing ensemble techniques resulting in high relative precisionphotometry. In total, 38 previously undetected variable stars werediscovered and can be characterized as follows: 1 irregular (probablypulsating) variable, 6 delta Scuti variables, 13 detached eclipsingbinary systems, 17 W UMa variables, and 1 unidentified variable. Twoadditional objects show evidence of variability and are likely detachedeclipsing binary systems. Previous proper motion studies of M11 allowfor membership determination for the bright stars, while the significantpopulation of field stars significantly hampers membership determinationfor the fainter variable stars. Several variables have been identifiedas important for follow-up studies.
| Ages and metallicities of star clusters: New calibrations and diagnostic diagrams from visible integrated spectra
We present homogeneous scales of ages and metallicities for starclusters from very young objects, through intermediate-age ones up tothe oldest known clusters. All the selected clusters have integratedspectra in the visible range, as well as reliable determinations oftheir ages and metallicities. From these spectra equivalent widths (EWs)of K Ca II, G band (CH) and Mg I metallic, and Hδ, Hγ andHβ Balmer lines have been measured homogeneously. The analysis ofthese EWs shows that the EW sums of the metallic and Balmer H lines,separately, are good indicators of cluster age for objects younger than10 Gyr, and that the former is also sensitive to cluster metallicity forages greater than 10 Gyr. We propose an iterative procedure forestimating cluster ages by employing two new diagnostic diagrams and agecalibrations based on the above EW sums. For clusters older than 10 Gyr,we also provide a calibration to derive their overall metal contents.
| New variable stars in open clusters. I. Methods and results for 20 open clusters
We present high precision CCD photometry of 1791 objects in 20 openclusters with an age of 10 Myr to 1 Gyr. These observations wereperformed within the Δ a photometric system which is primarilyused to detect chemically peculiar stars of the upper main sequence.Time bases range from 30 min up to 60 days with data from severalnights. We describe the time series analysis reaching a detection limitof down to 0.006 mag for apparent variability. In total, we havedetected 35 variable objects of which four are not members of theircorresponding clusters. The variables cover the entireHertzsprung-Russell diagram, hence they are interesting targets forfollow-up observations.Based on observations obtained at Complejo Astronómico elLeoncito (CASLEO), operated under the agreement between the ConsejoNacional de Investigaciones Científicas y Técnicas de laRepública Argentina and the National Universities of La Plata,Córdoba y San Juan; ESO-La Silla and UTSO-Las Campanas.
| Homogeneous Photometry. III. A Star Catalog for the Open Cluster NGC 6791
We present broadband BVI photometry for the open cluster NGC 6791, basedupon analysis of 1764 individual CCD images. We discuss in detail thetransformation of the instrumental magnitudes to the standardphotometric system of Landolt and then discuss methods for selecting asubset of cluster stars whose photometric indices are most likely to beof high reliability. Color-magnitude and color-color diagrams for thecluster are presented and discussed. A detailed comparison of thisphotometry with the results of previous observational studies ispresented. We make preliminary comparisons with theoretical isochronesprovided by D. A. VandenBerg and conclude that an excellent match can beachieved if the metal abundance and age of the cluster are both near theupper end of the range of recent estimates ([Fe/H]~+0.3, age~12 Gyr) andthe reddening and true distance modulus are both near the low end of therange of recent estimates [E(B-V)~0.09 mag and (m-M)0~12.79mag] if the isochrone predictions are reliable. A companion paper willdiscuss candidate variable stars and stars possibly showing planetarytransits. Data tables listing measured magnitudes and standard errors,image-quality indices, a variability index, and equinox J2000.0equatorial coordinates for 14,342 stars to V~24 have been made availableto the public through the services of the Canadian Astronomy DataCentre. Equatorial coordinates only have been provided for a further1916 stars, the photometry for which we were unable to calibrate becauseof lack of color information.Based in part on observations made with the Nordic Optical Telescope,operated on the island of La Palma jointly by Denmark, Finland, Iceland,Norway, and Sweden, in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofísica de Canarias.
| Recent developments on studies of open clusters
Studies on open clusters are of great significance for astronomy andastrophysics, for which distinct developments have been made recently inboth observational and theoretical respects. In this paper, currentresearch of open cluster is reviewed, and membership determination,basic parameters determination, evolution of cluster and clustermembers, structure and dynamics of open cluster are also described indetail.
| Metallicity distribution on the galactic disk
Depending mainly on UBVCCD data, the metallicities of 91 open starclusters nearby the galactic disk have been estimated using Cameron's[A&A 147 (1985b) 39] method. The metallicity radial gradient alongthe galactic plane is found to be -0.09 dex/kpc; which is in a very goodagreement with Panagia and Tosi [A&A 96 (1981) 306] and Carraro etal. [MNRAS 296 (1998) 1045]. Vertically on the galactic disk, withinabout 800 pc, the metallicity gradient is found to be so trivial. Anaverage age-metallicity relation has been examined, which confirms theprevious suggestion that the metallicity of a cluster depending mainlyon its position on the galactic disk more than its age.
| The forgotten star atlas : John Bevis's Uranographia Britannica.
Not Available
| Proper Motions of Open Star Clusters and the Rotation Rate of the Galaxy
The mean proper motions of 167 Galactic open clusters withradial-velocity measurements are computed from the data of the Tycho-2catalog using kinematic and photometric cluster membership criteria. Theresulting catalog is compared to the results of other studies. The newproper motions are used to infer the Galactic rotation rate at the solarcircle, which is found to be ω0=+24.6±0.8 km s-1 kpc-1.Analysis of the dependence of the dispersion of ω0 estimates onheliocentric velocity showed that even the proper motions of clusterswith distances r>3 kpc contain enough useful information to be usedin kinematic studies demonstrating that the determination of propermotions is quite justified even for very distant clusters.
| On the Galactic Disk Metallicity Distribution from Open Clusters. I. New Catalogs and Abundance Gradient
We have compiled two new open cluster catalogs. In the first one, thereare 119 objects with ages, distances, and metallicities available, whilein the second one, 144 objects have both absolute proper motion andradial velocity data, of which 45 clusters also have metallicity dataavailable. Taking advantage of the large number of objects included inour sample, we present an iron radial gradient of about -0.063+/-0.008dex kpc-1 from the first sample, which is quite consistentwith the most recent determination of the oxygen gradient from nebulaeand young stars, about -0.07 dex kpc-1. By dividing clustersinto age groups, we show that the iron gradient was steeper in the past,which is consistent with the recent result from Galactic planetarynebulae data, and also consistent with inside-out galactic diskformation scenarios. Based on the cluster sample, we also discuss themetallicity distribution, cluster kinematics, and space distribution. Adisk age-metallicity relation could be implied by those properties,although we cannot give conclusive result from the age- metallicitydiagram based on the current sample. More observations are needed formetal-poor clusters. From the second catalog, we have calculated thevelocity components in cylindrical coordinates with respect to theGalactic standard of rest for 144 open clusters. The velocitydispersions of the older clusters are larger than those of youngclusters, but they are all much smaller than that of the Galactic thickdisk stars.
| CCD photometric search for peculiar stars in open clusters. V. NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756
We have investigated 1008 objects in the area of five intermediate ageopen clusters (NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756) viathe narrow band Δ a-system. The detection limit for photometricpeculiarity is very low (always less than 0.009 mag) due to the highnumber of individual frames used (193 in total). We have detected sixpeculiar objects in NGC 6705 and NGC 6756 from which one in the latteris almost certainly an unreddened late type foreground star. Theremaining five stars are probably cluster members and bona fidechemically peculiar objects (two are łambda Bootis typecandidates). Furthermore, we have investigated NGC 3114, a cluster forwhich already photoelectric Δ a-measurements exist. A comparisonof the CCD and photoelectric values shows very good agreement. Again,the high capability of our CCD Δ a-photometric system to sort outtrue peculiar objects together with additional measurements from broador intermediate band photometry is demonstrated.Based on observations obtained at Complejo Astronómico elLeoncito (CASLEO), operated under the agreement between the ConsejoNacional de Investigaciones Científicas y Técnicas de laRepública Argentina and the National Universities of La Plata,Córdoba y San Juan; ESO-La Silla, UTSO-Las Campanas and L. FiglObservatory, Mt. Schöpfl (Austria).Figure 1 and Table 2 are only available in electronic form athttp://www.edpsciences.org
| Theoretical isochrones for the Delta a photometric system
We have calculated theoretical isochrones for the photometric Delta asystem to derive astrophysical parameters such as the age, reddening anddistance modulus for open clusters. The Delta a system samples the fluxdepression at 520 nm which is highly efficient to detect chemicallypeculiar (CP) objects of the upper main sequence. The evolutionarystatus of CP stars is still a matter of debate and very important totest, for example, the dynamo and diffusion theories. In fact, thedynamo or fossil origin of the magnetic fields present in this kind ofstar is still not clear. Using the stellar evolutionary models by Claret(\cite{Cla95}), a grid of isochrones with different initial chemicalcompositions for the Delta a system was generated. The published dataof 23 open clusters were used to fit these isochrones with astrophysicalparameters (age, reddening and distance modulus) from the literature. Asan additional test, isochrones with the same parameters for Johnson UBVdata of these open clusters were also considered. The fits show a goodagreement between the observations and the theoretical grid. We findthat the accuracy of fitting isochrones to Delta a data without theknowledge of the cluster parameters is between 5 and 15%.
| Urban Astronomy: Observing the Messier Objects from the City
Not Available
| Morphological analysis of open clusters' propertiesII. Relationships projected onto the galactic plane
A morphological analysis study of open clusters' properties has beenachieved for a sample of 160 UBVCCD open star clusters of approximately128,000 stars near the galactic plane. The data was obtained and reducedfrom using the same reduction procedures, which makes this catalogue thelargest homogeneous source of open clusters' parameters.
| Integrated spectral evolution of Galactic open clusters
We present a library of 47 open-cluster integrated spectra, mostlyobtained at CASLEO (San Juan, Argentina) in the range 3600 < λ< 7400 Å, which are made available at CDS. The data arecombined with previous spectra to obtain 10 high signal-to-noise ratiobasic templates in the young and intermediate-age domains, which arealso provided in the library. These Galactic disc templates representthe increased time resolution spectral evolution of a stellar populationunit around the Solar metallicity level. The improved signal-to-noiseratio of the present templates with respect to previous template lists,together with their increased time resolution, allowed us to improve thefundamental parameters of some open clusters. The present spectrallibrary will be useful for several astrophysical applications,particularly for population syntheses of star-forming giant galaxies.
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