The Dynamics of A2125
We present 371 galaxy velocities in the field of the very rich clusterA2125 (z~0.25). These were determined using optical spectroscopycollected over several years from both the WIYN 3.5 m telescope and NOAOMayall 4 m telescope. Prior studies at a variety of wavelengths (radio,optical, and X-ray) have indicated that A2125 is a likelycluster-cluster merger, a scenario that we are able to test using ourlarge velocity database. We identified 224 cluster galaxies, which weresubjected to a broad range of statistical tests using both positionaland velocity information to evaluate the cluster dynamics andsubstructure. The tests confirmed the presence of substructures withinthe A2125 system at high significance, demonstrating that A2125 is acomplex dynamical system. Comparison of the test results with existingsimulations strengthens the merger hypothesis and provides clues aboutthe merger geometry and stage. The merger model for the system canreconcile A2125's low X-ray temperature and luminosity with itsapparently high richness and might also explain A2125's high fraction ofactive galaxies identified in prior radio and optical studies.
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HD 52452: New BVRI Photometry
In this paper we report the multi-band BVRI photometry of HD 52452. Thecomparison of our data with previous observations reported by Messina etal. (2001) shows that there is a variation in amplitude, but the phasesof the two minima, thus the positions of the spot, are quite stableduring our observations.
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Keck Spectroscopy of Young and Old Star Clusters in NGC 1023
We present Keck/LRIS spectra for 11 old globular clusters in the S0-typegalaxy NGC 1023 and two young blue clusters in the nearby companion NGC1023A. Analysis of the spectra of seven old clusters with sufficientsignal-to-noise ratio shows generally good agreement betweenspectroscopic and previous photometric metallicity estimates, but theintegrated colors of two clusters are too blue for their spectroscopicmetallicities. Although the cluster ages are not well constrained, theyare most likely similar to those of Milky Way globular clusters andcertainly older than ~5 Gyr. The brightest globular cluster in thesample shows enhanced cyanogen, possibly indicating an abundance anomalysimilar to that observed in some M31 globular clusters. For the two blueclusters in NGC 1023A we estimate ages between 125 and 500 Myr on thebasis of their strong Balmer lines. The total masses are about8×104 Msolar and 6×104Msolar for a Miller-Scalo initial mass function and Z=0.004,making these objects similar to the young populous clusters in the LargeMagellanic Cloud. It is suggested that the two young clusters might haveformed during a period of enhanced star formation activity in NGC 1023A,stimulated by a close encounter with NGC 1023. Based on data obtained atthe W. M. Keck Observatory, which is operated as a scientificpartnership among the California Institute of Technology, the Universityof California and the National Aeronautics and Space Administration.
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The EUV Source HD 52452: Discovery of a Likely Triple System
We present the results of a photometric and spectroscopic study of theEUV bright source HD 52452. This star results to be a triple systemcomposed by a SB1 G5:V+G5:V close binary, which rotates with a periodP=0.423 days and by a slower rotating G5:V companion.
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Dynamics of cD Clusters of Galaxies. III. Redshift Data for 11 Abell Clusters
We present the final observational data for a spectroscopic study of asample of cD galaxy clusters. The goal of this program has been to studythe dynamics of the clusters, with emphasis on determining the natureand frequency of peculiar-velocity cD galaxies. In this paper we presentredshifts for 762 galaxies in the fields of the rich Abell clustersA779, A1691, A1749, A1767, A1837, A1927, A2067, A2079, A2089, A2199, andA2666. We also present preliminary dynamical properties for theseclusters using our measured redshifts.
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Observations of High Dispersion Clusters of Galaxies: Constraints on Cold Dark Matter
We have studied the dynamics of several Abell clusters of galaxies,which were previously reported to have large velocity dispersions, andhence very large masses. In particular, we have investigated theassertion of Frenk et al. (1990) that clusters with intrinsic velocitydispersions ~> 1200 km s^-1^ are extremely rare in the universe, andthat large observed dispersions are due to projection effects. We reportredshifts for 303 galaxies in the fields of A1775, A2029, A2142, andA2319, obtained with the Nessie multifiber spectrograph at the Mayall 4m telescope. A1775 appears to be two poor, interacting clusters,separated in velocity space by ~3075 km s^-1^ (in the cluster restframe). A2029 has a velocity dispersion of 1436 km s^-1^, based on 85cluster member redshifts. There is evidence that a group or poor clusterof galaxies of slightly different redshift is projected onto (or ismerging with) the core of A2029. However, the combined kinematic andx-ray data for A2029 argue for an intrinsically large dispersion forthis cluster. Based on redshifts for 103 members of A2142, we find adispersion of 1280 km s^-1^, and evidence for subclustering. With 130redshifts in the A2319 field, we have isolated a subcluster ~10' NW ofthe cD galaxy. After its removal, A2319 has a velocity dispersion of1324 km s^-1^. The data obtained here have been combined with recentoptical and X-ray data for other supposedly high-mass clusters to studythe cluster velocity dispersion distribution in a sample of Abellclusters. We find that clusters with true velocity dispersions ~>1200 km s^-1^ are not extremely rare, but account for ~5% of all Abellclusters with R >= 0. If these clusters are in virial equilibrium,then our results are inconsistent with a high-bias (b~>22),high-density CDM model.
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Dynamics of cD clusters of galaxies. I - Redshift data for seven clusters
We present the initial results of a spectroscopic study of a sample ofcD galaxy clusters. The goal of this program is to study the dynamics ofthe clusters, with emphasis on determining the nature and frequency ofpeculiar velocity cD galaxies. In this paper we present redshifts for611 galaxies in the fields of the rich Abell clusters A193, A399, A401,A1795, A1809, A2063, and A2124. We discuss our data reductiontechniques, and compare our derived velocities with previously publishedvalues. We find a frequency of emission line galaxies of about 6 percentin clusters, a factor of 2-3 less than the field.
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Structure, rotation, and the peculiar velocity cD galaxy in Abell 2107
The radial velocities of 75 galaxies in the field of Abell 2107 weremeasured within the framework of a program to study the kinematics of cDclusters of galaxies. Sixty-eight of these galaxies are cluster members.The mean observed velocity of A2107 is 12335 +/- 86 km/s, and thevelocity dispersion is 672 +67/-52 km/s. The cD galaxy has a peculiarvelocity of 270 km/s with respect to the cluster mean. The distributionof velocities is well fitted by a Gaussian, but the velocities arespatially correlated. Simple two-body subcluster models for A2107 areinvestigated; they are found to be consistent with the observed data andto account for the peculiar velocity of the cD galaxy. Alternatively,the spatial distribution of the velocities is also consistent withrotation of the single cluster at the 98-percent confidence level.
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A critical appraisal of published values of (Fe/H) for K II-IV stars
'Primary' (Fe/H) averages are presented for 373 evolved K stars ofluminosity classes II-IV and (Fe/H) values beween -0.9 and +0.21 dex.The data define a 'consensus' zero point with a precision of + or -0.018 dex and have rms errors per datum which are typically 0.08-0.16dex. The primary data base makes recalibration possible for the large(Fe/H) catalogs of Hansen and Kjaergaard (1971) and Brown et al. (1989).A set of (Fe/H) standard stars and a new DDO calibration are given whichhave rms of 0.07 dex or less for the standard star data. For normal Kgiants, CN-based values of (Fe/H) turn out to be more precise than manyhigh-dispersion results. Some zero-point errors in the latter are alsofound and new examples of continuum-placement problems appear. Thushigh-dispersion results are not invariably superior to photometricmetallicities. A review of high-dispersion and related work onsupermetallicity in K III-IV star is also given.
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A spectroscopic survey of high-latitude fields and comparison to Galaxy models
The results of a spectroscopic survey of the stellar populations ofhigh-Galactic latitude fields in SA 94 and Serpens are presented andanalyzed. A set of six spectrophotometric indices is used to provideinformation on both the number and metallicity of evolved stars, whilemeasurement of another 11 spectrophotometric indices provides anestimate of (Fe/H) good to 0.25 dex for the evolved stars identified ineach field. A detailed comparison of the data with predictions of thestandard Bahcall-Soneira Galaxy model reveals serious discrepancies. Theproperties of giants with roughly solar metallicity are described wellby the disk giants predicted by the standard model. The sample isdominated by intermediate-metallicity giants whose properties are welldescribed by a thick-disk component with scale height of approximately700 pc that makes up about 5 percent of the solar neighborhood stellardensity.
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E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
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The kinematic properties of faint elliptical galaxies
Rotation curves and velocity dispersion profiles are obtained for 11faint elliptical galaxies, together with central velocity dispersionsfor an additional six faint ellipticals. It is noted that faintellipticals rotate more rapidly than bright ellipticals, and almost asrapidly as predicted by models with oblate figures and isotropicdistributions of residual velocities. No significant difference is foundbetween disk galaxy bulge rotational properties and ellipticals withsimilar absolute magnitudes, when ellipticity differences are taken intoaccount. Attention is given to the relation between central velocitydispersion and luminosity, and indication is found that it may besteeper at low luminosities. It may be possible to satisfy the empiricalcorrelation between rotation and luminosity, if the ellipticals formedin a clustering hierarchy, although the slow rotation of brightellipticals is difficult to reconcile with their high densities
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A survey of galaxy redshifts. I - Data reduction techniques
A magnitude-limited redshift survey of galaxies having B magnitudes nofainter than 14.5, galactic latitudes no less than 40 deg, andnonnegative declinations is currently being undertaken. This paperpresents in some detail the methods of data reduction, which are basedon cross correlation against filtered templates. Expressions arepresented for the uncertainty of a measured redshift, for the internalbroadening of the object, and for the uncertainty of this broadening.Comparison of the optical data with previously published 21-cm datashows no systematic errors and yields excellent agreement with theinternal error analysis. The method of analyzing velocity dispersions isquite promising for further application. A series of spectra arepresented as examples to show the power and limitations of thecorrelation techniques.
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Observations of occultations of stars by the moon
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..395H&db_key=AST
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Determination of atmospheric parameters for G and K giants by means of photoelectric indices.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....15..123H&db_key=AST
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UBV photometry of 550 F, G and K type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966MNRAS.133..475A&db_key=AST
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Photometry of the orange-red Ca I triplet in late-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964MNRAS.128..475P&db_key=AST
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Hα Photometry of late-type stars I. F, G and K-type stars north of the equator
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964MNRAS.128..435P&db_key=AST
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The magnesium b lines in late-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.121...52D&db_key=AST
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Stellar groups, V. Luminosities, motions and masses of the late-type sub-giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.120..430E&db_key=AST
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Photoelectric measurements of the λ4200 A CN band and the G band in G8-K5 spectra
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.120..287G&db_key=AST
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A Catalogue of High-Velocity Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2..195R&db_key=AST
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