Probable nonradial g-mode pulsation in early A-type stars
Context: . Aims: .Asteroseismology of early A-type stars could bea new tool to test stellar convection theories. Methods: .A surveyfor line profile variability in early A-type stars has been performed inorder to detect nonradial pulsation signatures. Results: .The starHR 6139, with spectral type A2V and estimated T{eff}=8800 K,shows evident line profile variations that can be explained byoscillations in prograde g-modes. This feature and the known photometricvariability are similar to those observed in the Slowly Pulsating B-typestars. However HR 6139 is much cooler than the cool border of theinstability strip of such variables, and it is hotter than the blue edgeof the δ Scuti instability strip. There are indications of a tinyvariability also in other four objects, whose nature is not yetclear. Conclusions: .
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CHARM2: An updated Catalog of High Angular Resolution Measurements
We present an update of the Catalog of High Angular ResolutionMeasurements (CHARM, Richichi & Percheron \cite{CHARM}, A&A,386, 492), which includes results available until July 2004. CHARM2 is acompilation of direct measurements by high angular resolution methods,as well as indirect estimates of stellar diameters. Its main goal is toprovide a reference list of sources which can be used for calibrationand verification observations with long-baseline optical and near-IRinterferometers. Single and binary stars are included, as are complexobjects from circumstellar shells to extragalactic sources. The presentupdate provides an increase of almost a factor of two over the previousedition. Additionally, it includes several corrections and improvements,as well as a cross-check with the valuable public release observationsof the ESO Very Large Telescope Interferometer (VLTI). A total of 8231entries for 3238 unique sources are now present in CHARM2. Thisrepresents an increase of a factor of 3.4 and 2.0, respectively, overthe contents of the previous version of CHARM.The catalog is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/431/773
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J - K DENIS photometry of a VLTI-selected sample of bright southern stars
We present a photometric survey of bright southern stars carried outusing the DENIS instrument equipped with attenuating filters. Theobservations were carried out not using the survey mode of DENIS, butwith individual target pointings. This project was stimulated by theneed to obtain near-infrared photometry of stars to be used in earlycommissioning observations of the ESO Very Large TelescopeInterferometer, and in particular to establish a network of brightcalibrator sources.We stress that near-infrared photometry is peculiarly lacking for manybright stars. These stars are saturated in 2MASS as well as in regularDENIS observations. The only other observations available for brightinfrared stars are those of the Two Micron Sky Survey dating from overthirty years ago. These were restricted to declinations above≈-30°, and thus cover only about half of the sky accessible fromthe VLTI site.We note that the final 2MASS data release includes photometry of brightstars, obtained by means of point-spread function fitting. However, thismethod only achieves about 30% accuracy, which is not sufficient formost applications.In this work, we present photometry for over 600 stars, each with atleast one and up to eight measurements, in the J and K filters. Typicalaccuracy is at the level of 0\fm05 and 0\fm04 in the J and K_s bands,respectively.Based on observations collected at the European Southern Observatory, LaSilla.Tables 1 and 2 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/413/1037
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Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
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CHARM: A Catalog of High Angular Resolution Measurements
The Catalog of High Angular Resolution Measurements (CHARM) includesmost of the measurements obtained by the techniques of lunaroccultations and long-baseline interferometry at visual and infraredwavelengths, which have appeared in the literature or have otherwisebeen made public until mid-2001. A total of 2432 measurements of 1625sources are included, along with extensive auxiliary information. Inparticular, visual and infrared photometry is included for almost allthe sources. This has been partly extracted from currently availablecatalogs, and partly obtained specifically for CHARM. The main aim is toprovide a compilation of sources which could be used as calibrators orfor science verification purposes by the new generation of largeground-based facilities such as the ESO Very Large Interferometer andthe Keck Interferometer. The Catalog is available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/386/492, and from theauthors on CD-Rom.
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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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Research Note Hipparcos photometry: The least variable stars
The data known as the Hipparcos Photometry obtained with the Hipparcossatellite have been investigated to find those stars which are leastvariable. Such stars are excellent candidates to serve as standards forphotometric systems. Their spectral types suggest in which parts of theHR diagrams stars are most constant. In some cases these values stronglyindicate that previous ground based studies claiming photometricvariability are incorrect or that the level of stellar activity haschanged. Table 2 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/367/297
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Near infrared light variations of chemically peculiar stars. The SrCrEu stars
Twenty magnetic Chemically Peculiar (CP2) stars of the SrCrEu subgroupmostly brighter than the 7.5 visual magnitude have been investigated inthe near infrared at 1.25, 1.6 and 2.2 mu . The stars HD 3980, HD 24712,HD 49976, HD 83368, HD 96616, HD 98088, HD 118022, HD 125248, HD 148898,HD 203006, and HD 220825 have been found to be variable in the infraredwith the same period as the visible light, spectrum, and magnetic fieldvariations. HD 221760 is also variable with a period of 12.45 days,which has to be confirmed. The stars HD 72968, HD 111133, HD 126515, HD153882, and HD 164258 do show some hint of variability, although thedata are too few. Infrared variability has been detected for the firsttime in the stars HD 101065, and HD 206088, which have not yet beenconsidered as variable. No variability has been detected for the star HD137949 within a time scale of the order of ten days. Based onobservations collected at the European Southern Observatory, La SillaChile.
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The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
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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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Observations of lunar occultations at Observatoire de la Cote d'Azur.
The results of 114 photoelectric observations are analysed. They wereobtained at the two stations of O.C.A.: Calern and Nice Observatories.We first give a short description of the two photometers used and thenwe present the interactive reduction method. The astrometric andphotometric parameters are derived from each light-curve. Finally wesummarize the results and discuss about the non point-like occultedstars: we present 38 double star measurements, for 16 objects, and 11determinations of angular diameters, for 4 objects.
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The near-infrared variation of the magnetic star HD 125248
The magnetic chemically peculiar star HD 125248 has been found to bevariable in the near-infrared at 1.25, 1.6, and 2.2 microns. Theinfrared variation occurs within the same period as the visible light,spectrum, and magnetic field variations. The infrared light curves areall in phase with each other and their amplitude, although smaller thanin the visible, is nearly the same in all three filters. Using our uvbyobservations and those available in the literature, we have also foundthe best value of the period to be: P = 9.29571 (+/- 0.00018) d. Fromthe analysis of the phase relations among the near infrared lightcurves, the visible ones and the magnetic field variation of HD 125248,we have found that the magnetic field extrema do coincide in time withinfrared light extrema. This result is discussed in terms of thepossible influence of the magnetic pressure term on the hydrostaticequilibrium of the upper atmosphere.
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A new determination of the Geneva photometric passbands and their absolute calibration
The calibration of the Geneva photometric system's passbands is revised.New response functions are presented in tabular form for an equiphotonicflux. An absolute spectrophotometric adjustment is used to obtain acorresponding spectrophotometric description in SI units for each entryof the Geneva catalog. The definition and means of computing thenecessary quasi-isophotal frequencies or wavelengths are given. Thecoherence of the Geneva catalog with several sets of absolutespectrophotometric data is examined. A correction is proposed for theentire catalog of Gunn and Stryker (1983).
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UBV Photoelectric Photometry Catalogue (1986). III Errors and Problems on DM and HD Stars
Not Available
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A search for low-harmonic pulsation in the AP star CS VIR
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985MNRAS.212..337K&db_key=AST
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Calibration in temperature of photometric parameters
In calibrating photometric parameters in temperature, it is very easy touse a Planck distribution to show that a color index is a temperatureparameter, but it is more difficult to calibrate such a color index interms of temperature because only a few effective temperature values aredetermined. A pioneering work is that of Kuiper (1938), who derived atemperature scale according to spectral type (from A0 to M2 for dwarfsand from G0 to M8 for giants) and a Becker index. The first study givinga relation between effective temperature and a photoelectric color indexis that of Popper (1959) in which Popper derives a relation betweeneffective temperature and B-V for the A and F stars and for G8 to K5(dwarf and giant) stars. Popper has shown the relation betweentemperature parameters of two photometric systems, R-I from thesix-color system of Stebbins and Whitford, and B-V. The intent of thepresent work is to define a set of stars which can be used to determinea calibration of a photometric parameter in terms of effectivetemperature.
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The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
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Spectrophotometry of B, A, and F stars. II
Optical region energy distributions of 35 normal B, A, and F stars arepresented consistent with the Hayes-Latham calibration of Vega. Upperlimits on the photometric accuracy are derived by a comparison ofobserved and synthesized u-b and b-y indices for each observer.Effective temperatures are found using the empirical calibration of Codeet al. (1976) and the fully line blanketed solar composition modelatmospheres of Kurucz (1979).
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Spectrophotometry of peculiar B and A stars. IV - Secondary standards and the AP stars HD 10783 and CU Virginis
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980AJ.....85..836W&db_key=AST
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Observational evidence for the pulsational stability of some AP stars
Sixteen peculiar A type stars (one of them questionable) and two Amstars have been observed photometrically during a continuous observingrun of 2 to 4 hours each, to check them for pulsational stability. AllAp stars proved to be of constant brightness to within about thestandard duration of 0.002 to 0.003 mag, except for an eventuallong-term variability due to rotation. Therefore, no observationalevidence from this side can be brought up against diffusion as apossible mechanism responsible for peculiar atmospheres. Both Am starsalso proved to be of constant brightness. Four new pulsating variablestars have been discovered from observations in the program.
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Photoelectric observations of the AP stars HD 125248, HD 134793 and HD 184905.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...31..205B&db_key=AST
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Photoelectric filter photometry of the flux depression at 5200 A in Ap-stars
A new photometric index was used to characterize the flux depression at5200 A in a photoelectric filter photometric study of a large number ofnormal A-stars, Ap-stars, Am-stars, and Hg-Mn-stars. The new index isdefined as a = g - (h + y)/2, where g and h are the brightnesses at 5240and 5020 A, respectively, measured by interference filters, and y is thebrightness measured with a Stromgren filter. The index reveals a markedcontrast between normal and peculiar stars.
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Rotational Velocities of a0 Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..101D&db_key=AST
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Four-colour and H BET photometry of some bright southern stars- II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.160..155S&db_key=AST
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11-Farben-Photometrie des magnetischen Veranderlichen HD 125248.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&A....16..385M&db_key=AST
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UVBY photometry of AP stars : the nature of the light variations.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..422W&db_key=AST
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Magnetic Observations of White Dwarfs
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...160L.147A&db_key=AST
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UBV Beobachtungen des magnetischen Veranderlichen Sterns HD 125248.
Not Available
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The corrected magnitudes and colours of 278 stars near S.A. 1-139 in the UBV system
Not Available
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U, b, v, and Hβ Photometry for the Bright B8- and B9-TYPE Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963ApJ...137..530C&db_key=AST
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INHABITED SKY
