A Photometric Study of ZZ Microscopium
New photometric (uvby?) observations of ZZ Mic are described.Reddening values O-C values, and we confirmed a sign that the period isincreasing.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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Binarity and multiperiodicity in high-amplitude delta Scuti stars .
We present our first results for a sample of southern high-amplitudedelta Scuti stars (HADS), based on a spectrophotometric survey startedin 2003. For CY Aqr and AD CMi, we found very stable light and radialvelocity (RV) curves; we confirmed the double-mode nature of ZZ Mic, BQInd and RY Lep. Finally, we detected gamma -velocity changes in RS Gruand RY Lep.
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A photometric monitoring of bright high-amplitude delta Scuti stars. I. The double-mode pulsation of V567 Ophiuchi
We present the first results of an observational project, whichaddresses the period changing behaviour of a sample of high-amplitudedelta Scuti stars. In this paper we discuss the double-mode nature ofV567 Ophiuchi. It was observed on 15 nights in two consecutive years inorder to resolve the long-standing ambiguity related to its secondaryperiod. A frequency analysis of almost 5000 individual single-filteredCCD V measurements resulted in two independent frequencies(f1=6.6879 d-1 and f2=11.8266d-1) with a ratio of f1/f2=0.565.Earlier data taken from the literature were used to refine the dominantperiod, and the re-analysis supports the existence of the secondaryperiod. Possible asteroseismological implications are briefly discussed.
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δ Scuti stars and their related objects
δ Scuti stars are a group of stars located on or a little abovethe main sequence of H-R diagram with spectral type from A3 to F5. Theyare low amplitude single or multi period pulsators with period shorterthan 0.3 d. Within the same area there are several groups of variablesor special stars correlated with them, e.g., Dwarf Cepheids, γ Dorvariables, Blue Stragglers, Am stars, Ap stars, ROAp variables, λBoo variables and δ Del variables. In this paper a general reviewin this field, including the number of new variables discovered after1995, is presented. The most reliable period variation rates for all thehigh amplitude variables and several low amplitude variables are listed.Statistic shows the higher the rotation rate v sin i is, the lower thelight variation amplitude is. Thus within young open clusters highamplitude variables cannot be found. The amplitudes-periods distributionhave 3 peaks with the highest of 1.0 mag in V at 0.17 d in period. Forδ Scuti variables in stellar systems the shorter the averageperiod is, the lower the metallicity and the older the age of thestellar system are.
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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
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A revised catalogue of delta Sct stars
An extensive and up-dated list of delta Sct stars is presented here.More than 500 papers, published during the last few years, have beenrevised and 341 new variables have been added to our last list, sixyears ago. This catalogue is intended to be a comprehensive review onthe observational characteristics of all the delta Sct stars known untilnow, including stars contained in earlier catalogues together with othernew discovered variables, covering information published until January2000. In summary, 636 variables, 1149 references and 182 individualnotes are presented in this new list. Tables 1 and 2 will be accessibleonly 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
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The light curves of SX Phe stars in NGC 6752
The light curves of the SX Phe stars found in the globular cluster NGC6752 were processed and the properties of their Fourier parameters werediscussed
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Stability in the Light Curves of High-Amplitude delta Scuti Stars: Selected Monoperiodic Stars
We have analyzed all the reliable photometric data sets available in thebibliography for a selected sample of monoperiodic high-amplitude deltaScuti stars in order to study the stability of their light curves. Atotal of 169 data sets and more than 22,000 points have been consideredfor seven stars: ZZ Mic, EH Lib, BE Lyn, YZ Boo, SZ Lyn, AD CMi, and DYHer. The results do not reveal significant long-term changes ofamplitude of the light curves for any of these stars.
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The light curves of the short-period variable stars in omega Centauri
The Fourier decomposition was applied to the light curves of the shortperiod variable stars discovered by the OGLE team (Kaluzny et al. 1996,1997) in omega Cen. The progression of the {f_2} u parameter as afunction of the period is extended toward very short periods as the newvalues connected directly to those of stars located in the Galaxy.However, two groups of stars deviate: the first is located around 0.038d and it shows rather high {f_2} u values; the second is the origin of asmall change in the slope around 0.050 d. The reality of the twofeatures is discussed. The peculiarity of the light curve of OGLEGC 26is also emphasized.
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The light curves of the short-period variable stars in the Carina dwarf Spheroidal galaxy
The light curves of the high-amplitude, short-period variable starsdiscovered by Mateo et al. (1998) in the Carina dwarf Spheroidal Galaxywere re-analyzed to refine their properties and compare them with thoseof galactic stars. In spite of a different pulsation mode established bymeans of different PLM relationships, the Fourier parameters did notreveal a separation between the two groups; however, they are slightlydifferent from those of galactic stars. The possibility that some ofthese stars are double-mode pulsators is suggested.
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Photometric Abundance Calibration of delta Scuti Stars Using HK Photometry
The hk index has been used as a metallicity indicator for RR Lyraevariable stars. It is now being applied to the shorter period deltaScuti variables. Employing spectroscopic abundances of stars withpublished hk values and photometric indices calculated from stellaratmosphere models, a three-dimensional interpolation is used todetermine [Fe/H] from intrinsic b-y, c_1, and hk values. The resulting[Fe/H], log g, and T_eff values for 10 delta Scuti stars are presented.
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The delta Scuti Star GSC 2985-01044
GSC 2985-01044 is a delta Scuti star with a period of 0.0933584 days anda V-magnitude range of 11.85-12.05 its light curve is slightly variable.The location, space motion, and other properties of this star indicatethat it is a higher amplitude delta Scuti star (or ``dwarf Cepheid'')that is a member of the old disk population. The problem of determiningthe local space densities of the various populations of the higheramplitude delta Scuti stars is discussed.
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HIPPARCOS parallaxes and period-luminosity relations of high-amplitude delta Scuti stars
Hipparcos parallaxes of high-amplitude delta Scuti stars are used toderive a period-luminosity relation with a scatter of about +/-0.1 mag,which is independent from photometric calibrations to absoluteluminosities. Comparisons with several P-L relations from the literatureshow satisfactory agreement, and all deviations from the Hipparcos meanrelation can be explained by uncertainties in the data available beforeHipparcos. Hipparcos data for a few stars of relatively small anduncertain parallaxes indicate that they may have systematically very lowluminosity. However, briefly discussing Lutz-Kelker corrections andconsidering the full sample of high-amplitude delta Scuti stars, it isconcluded that this sample is homogeneous and has similar basic physicalproperties as the ``normal'' low-amplitude delta Scuti stars. It isemphasized that the Hipparcos P-L relation defines a new distance scalewhich is independent from those of the classical Cepheids and RR Lyraestars. Therefore, observations of high-amplitude delta Scuti stars canbe used to check fundamental distance determinations to e.g. globularclusters, the Galactic bulge and the Magellanic Clouds.
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Structural Properties of Pulsating Star Light Curves Through Fuzzy Divisive Hierarchical Clustering
Not Available
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Pulsation in high amplitude delta Scuti stars.
It has been pointed out by earlier authors that radial pulsation seemsto be the only type present in high amplitude δ Sct stars, atleast for monoperiodic stars. In order to confirm this or not, we havecollected all the multicolor data available for these stars in theStroemgren and Johnson photometric systems. Then, the type of pulsationhas been analysed on the basis of the phase shifts and amplitude ratiosbetween observed light and colour variations. The results indicate thatall the stars analysed, including both high amplitude δ Sct(Population I) and SX Phe (Population II) stars, are radial pulsators.This is also true for the monoperiodic medium amplitude δ Sctstars analysed.
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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.
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A catalogue of variable stars in the lower instability strip.
Identifications, positions, photometry, spectra, some pulsationalfeatures, other astrophysical parameters and literature for 302pulsating variable stars in the lower instability strip, near the ZAMS,are given. About 185 stars have near homogeneous photometric informationin the Stroemgren's uvby-β photometric system. Thiscatalogue/database covers information published until November 1993.
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δ Scuti stars: a new revised list
An extensive and up to date list of δ Sct stars is presented. Thiscatalogue is intended to be a comprehensive review of observationalcharacteristics of all the δ Sct stars known until now, includingstars contained in earlier catalogues together with other new discoveredvariables, covering information published until November 1993. Globalinformation in the form of histograms and diagrams are also shown.
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A review on Delta Scuti stars and related objects.
Not Available
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Period variations and evolution of Delta Scuti variables
The Short periods of Delta Scuti Stars allow observational detection ofthe period changes expected from the stellar evolution within severaltens years. For about 30 years we have kept this topic as a smallsystematic observational program with our 60 cm telescope. Here wepublish the period variation of 18 stars . The data of 28 And are takenfrom R. Garrido et al. (1983), 211; the period variation rate of 4 CVnis given by M. Breger. Both of them are low amplitude variables.
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Empirical P-L-C relation for Delta Scuti stars - A catalogue
An extensive and up-to-date list of 192 Delta Scuti stars is presented.Empirical period - luminosity - color (P-L-C) relations are obtained forthe four lowest modes corresponding to radial pulsations. Agreement withpredicted values indicates that, in general, both Stroemgren photometriccalibration and pulsation theory work well for these stars.
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The radii and masses of dwarf Cepheids
A radial velocity curve for CY Aqr, and VJK photometry for CY Aqr, YZBoo, and VZ Cnc, are used to derive absolute magnitudes and masses forthese three dwarf Cepheids. If dwarf Cepheids are earlypost-main-sequence stars, a pulsation mass of 1.2 + or - 0.3 solarmasses is found, and the pulsation mass to evolutionary mass ratio isabout 0.75. A mean value of -8.6 x 10 to the -11th days/day for theperiod changes is derived which is an order of magnitude larger thanpredicted by early post-main-sequence evolutionary tracks. Problems inmodeling these stars at a more advanced evolutionary state are noted.Comparison is made between the properties of fundamental and possibleovertone pulsators. The possible relationship between Delta Scutibehavior and the small cycle-to-cycle variations found in dwarf Cepheidlight curves is also considered.
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Quasi-160-minute oscillation period of Delta Scuti stars
The resonance power spectrum (or commensurability spectrum) computed for217 Delta Scuti stars indicates that the dominant (most commensurate)period for the total set of oscillation periods of these stars is 162.2+ or - 2.8 min. Within the error limits, this period coincidesapproximately with the 160-min period of global oscillations of the sun.
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Fourier decomposition of the light curves of high amplitude Delta Scuti and SX Phe stars
The light curves of monoperiodic, high amplitude ? Scuti and SXPhe stars have been Fourier decomposed in order to study theirstructural properties. The computed phase differences show a trend toincrease with the period similar to the trend observed in short periodCepheids and RR Lyrae stars. There is some evidence of a separation ofthe light curves in two groups, which indicates the presence of twotypes of pulsation. The proposed separation is discussed taking alsointo account the amplitude-amplitude diagrams, and some comparisons withRR Lyrae star light curves are made. For the present there are noevident physical differences between the stars in the two groups whichcan explain the separation.
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The rotational velocities of the dwarf Cepheids and related stars
The rotational velocities of the dwarf Cepheids are discussed, and someapparent differences between the dwarf Cepheids and the delta Scutivariables (other than light amplitude) are noted. For dwarf Cepheids,the rotational velocities are very small compared with the typicalrotational velocity of delta Scuti variables. The dwarf Cepheids,moreover, are restricted to a much more confined region in the H-Rdiagram. Unlike many typical delta Scuti variables, no dwarf Cepheidsare found near the ZAMS.
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Revised list of pulsating stars with ultra-short periods
A comprehensive list of 178 known Delta Scuti and RR Lyrae-stars ispresented. Using this revised list a HR diagram for these ultra shortperiod pulsating stars is plotted and the blue and red edges of theresultant instability strip are determined. Selection effects arediscussed, and the PLC relationship of Breger (1979) is tested usingdata from this list. Stars lying outside the defined instability regionare discussed.
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IAU Archives of Unpublished Observations of Variable Stars
Not Available
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Photometry /VBLUW system/ of 26 RR Lyrae variables in the direction of a proposed intergalactic dust cloud in Microscopium
Abstract image available at:http://adsabs.harvard.edu/abs/1980A&AS...39..199V
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The nature of dwarf Cepheids. V - Analysis and conclusions
The various observational arguments that can be or have been used todetermine the nature of dwarf Cepheids are examined. Three evolutionaryhypotheses are outlined and shown to lead to different expected periodchanges. Despite careful analysis, the derived period changes do notprovide definite information on the evolutionary stage of most of thestars examined. Evidence for the Population I nature of most dwarfCepheids (which are normal delta Scuti stars with large amplitudes) ispresented.
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INHABITED SKY
