New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
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Kinematics, ages and metallicities of star clusters in NGC 1316: a 3-Gyr-old merger remnant
We report on multi-object spectroscopy in the red spectral region of 37candidate star clusters in an ~8×8arcmin2 field centredon the giant early-type radio galaxy NGC 1316 (Fornax A), the brightestgalaxy in the Fornax cluster. Out of this sample, 24 targets are foundto be genuine star clusters associated with NGC 1316, and 13 targets areGalactic foreground stars. For the star cluster sample, we measure amean heliocentric velocity vhel=1698+/-46kms-1 anda velocity dispersion σ=227+/-33kms-1 within agalactocentric radius of 24kpc. Partly responsible for the velocitydispersion is a significant rotation in the star cluster system, with amean velocity of ~175+/-70kms-1 along a position angle of~6°+/-18°. Using the projected mass estimator and assumingisotropic orbits, the estimated total mass is(6.6+/-1.7)×1011Msolar within a radius of24kpc. The mass is uncertain by about a factor of 2, depending on theorbital assumptions. The implied M/LB ratio is in the range3-6. Four star clusters in our sample are exceptionally luminous(MV<-12.3). This means that (1) at least this manyclusters in NGC 1316 are up to an order of magnitude more luminous thanthe most luminous star cluster in our Galaxy or M31, and that (2) theS/N ratio of their spectra allows us to measure line strengths with goodaccuracy. By comparing the measured colours and equivalent widths ofHα and the Caii triplet (λλ 8498, 8542, 8662Å)absorption lines for those bright star clusters in our sample with thoseof single-burst population models (the Bruzual & Charlot models), wefind that they are coeval with an age of 3.0+/-0.5Gyr. Theirmetallicities are found to be solar to within +/-0.15dex. We discuss theproperties of the main body of NGC 1316, and conclude that they areconsistent with having hosted a major merger 3Gyr ago as well. Thepresence of intermediate-age globular clusters in NGC 1316 shows onceagain that globular clusters with near-solar metallicity do form duringgalactic mergers, and, moreover, that they can survive disruptionprocesses taking place during the merger (e.g., dynamical friction,tidal disruption), as well as evaporation. In this respect, NGC 1316provides a hitherto `missing' evolutionary link between young mergerremnants of age ~0.5Gyr such as NGC 3597, 3921 and 7252 on one side andolder giant ellipticals featuring bimodal colour distributions on theother side.
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The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants
We present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
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Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
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Secondary standards for H-beta photometry in the Southern Hemisphere (second series).
Not Available
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UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
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Large and kinematically unbiased samples of G- and K-type stars. IV - Evolved stars of the old disk population
Modified Stromgren and (R,I) photometry, along with DDO and Genevaphotometry, are presented for a complete sample of evolved old-disk Gand K giants in the Bright Star Catalogue. Stars with ages of between1.5 x 10 to the 9th and 10 to the 10th yr are found to have anear-normal distribution of heavy element abundances, centered on anFe/H abundance ratio of -0.1 dex. The old disk clusters NGC 3680 and IC4651 contain red-straggler young-disk giants that are probablycontemporaries of the blue stragglers in the clusters.
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Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
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Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
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UBV photometry of E region standard stars of intermediate brightness
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
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Up-To UBVRI Values for the E-Region Standard Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...46....7V&db_key=AST
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Photometric standard stars for the UBV and (RI)KC systems.
Not Available
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Fainter Standards for VRI Photometry in the E Regions
Not Available
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VRI standards in the E regions
Not Available
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Standard Stars for VRI Photometry with S25 Response Photocathodes [Errata: 1974MNSSA..33....1C]
Not Available
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Standard magnitudes in the E regions.
Not Available
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