Optical-Turbulence and Wind Profiles at San Pedro Mártir
Results of monitoring optical-turbulence profiles and velocity of theturbulence layers at San Pedro Mártir, Mexico, are presented. Thedata were collected during 11 nights in April-May 1997 and 16 nights inMay 2000 using the Generalized Scidar of Nice University installed onthe 1.5-m and 2.1-m telescopes. The statistical analysis of the 6414turbulence profiles obtained shows that the seeing produced by theturbulence in the first 1.2 km, not including dome seeing, at the 1.5-mand the 2.1-m telescopes have median values of 0 to z 0. hss'' 63 and0 to z 0. hss'' 44, respectively. The dome seeing at those telescopeshave median values of 0 to z 0. hss'' 64 and 0 to z 0. hss'' 31. Theturbulence above 1.2 km and in the whole atmosphere produces seeing withmedian values of 0 to z 0. hss'' 38 and 0 to z 0. hss'' 71. Thetemporal correlation of the turbulence strength drops to 50% in timelags of 2 and 0.5 hours, approximately, for altitudes below and above 16km above sea level, respectively. The turbulence above 9 kmremained notably calm during 9 consecutive nights, which is encouragingfor adaptive optics observations at the site. The 3016 profiles of theturbulent-layer velocity that are analyzed show that the fastest layersare found between 10 and 17 km, where the tropopause and the jet streamare located, with median speed of 24.4 m s-1. In the first 2.2 km andabove 17 km, the turbulent layers move relatively slowly, with medianspeeds of 2.3 and 9.2 m s-1. The median of the wavefront coherence-timeis 6.5 ms, in the visible. The results obtained here places San PedroMártir among the best suited sites for installing next generationoptical telescopes.
|
Estimation of anisoplanatism in adaptive optics by generalized SCIDAR profiling
We present the results of contemporaneous seeing measurements using amulti-object Shack-Hartmann wavefront sensor, SCIDAR optical turbulenceprofiling, and a DIMM seeing monitor at the William Herschel Telescopein La Palma. The data are used to determine the accuracy with whichangular anisoplanatism can be predicted from generalized SCIDARturbulence profile measurements. Theoretical predictions of the angularcorrelation of the Zernike aberration coefficients, based on the SCIDARprofiles, agree with direct measurements from the wavefront sensor towithin 7 per cent rms. Estimates of the total seeing (integrated opticalturbulence strength) from the methods agree to 10 per cent rms. Weconclude that SCIDAR represents a reliable means for calibration of thespatially and temporally variable point-spread function for imaging withadaptive optics in astronomy.
|
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
|
First evidence of the finite horizontal extent of the optical turbulence layers. Implications for new adaptive optics techniques
It was recently shown (Masciadri et al. \cite{mas00}; Masciadri\cite{mas01a}), using a numerical simulation (Meso-Nh model), thatconsidering horizontally uniform CN2 can havesevere consequences. For example, the integration of theCN2 along lines of sight different from the zenithgives variations that can be larger than 0.50arcsec . In this paper wetry to validate this result following two approaches. (a) numericalapproach: we compare measured and simulated CN2profiles. The first ones were obtained with a Generalized Scidar (GS)and the latter are simulated with the Meso-Nh model at the same azimuthand elevation as those of the observations. Further measurements (DIMM,mast and balloons) are considered in order to support the comparison.(b) experimental approach: we compare CN2 profilesmeasured (almost simultaneously) by a GS along different lines of sight.The results of this study show that (1) the horizontal size of theturbulent layers can be finite, (2) the simulations and the measurementsare well correlated and (3) for the first time, we show that the modelcan reproduce observed seeing values that vary as much as 0.50arcsecduring the same night. This definitely shows that the numericalsimulations are a useful tool in the context of the turbulencecharacterization for astronomical applications. Finally, we discuss theimplications that a finite horizontal size of the turbulent layers couldhave on new adaptive optics techniques, particularly in applications tothe extremely large size telescopes.
|
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
|
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
|
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
|
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.
|
The metallicities and kinematics of RR Lyrae variables, 1: New observations of local stars
In order to study the structure and formation history of the galaxy, wehave obtained low-to-moderate dispersion spectra of 302 nearby RR Lyraevariables of Bailey type 'ab'. We derived abundances, typically accurateto 0.15-0.20 dex and calibrated to the Zinn & West (1984) globularcluster metallicity scale, from the pseudoequivalent widths of the Ca IIK, H delta, H gamma, and H beta lines. Radial velocities accurate tobetween 2 and 30 km/s were obtained from the spectra and from theliterature. Distances accurate to between 5% and 20% were derived frompublished apparent magnitudes and Burstein & Heiles (1982)reddenings. The metallicity distribution of the RR Lyrae stars peaks at(Fe/H)K approximately equals -1.5, and is narrower than thatof the Ryan & Norris (1991) subdwarfs, as expected since the mostmetal-rich and metal-poor progenitors preferentially appear as stablered and blue horizontal branch stars, rather than as RR Lyrae. Themetal-rich tail of the RR Lyrae distribution extends to(Fe/H)K approximately equals 0, and a qualitative analysis ofthe distribution of distances from the galactic plane shows that thestars in this tail (i.e., (Fe/H)K greater than -1.0) are moreconcentrated to the plane than the more metal-poor stars. The abundancedistribution of the local RR Lyrae stars is in excellent agreement withthe changing abundance distributions of distant RR Lyrae stars as afunction of galactocentric distance, as derived by Suntzeff et al.(1991), who ascribed this change to systematic variation in horizontalbranch morphology (probably age variations) with galactocentricdistance. The abundance distribution of the local RR Lyrae stars alsoagrees well with those of the distant RR Lyrae stars as a function ofdistance from the galactic plane. There is no evidence for an abundancegradient in this direction, suggesting that gaseous dissipation did notplay a major role in the formation of the outer halo.
|
Photometry of visual binaries most of which have known orbits
Photometric data of close visual binaries most of which have knownorbits are presented. The measurements were carried out with the areascanning technique. Magnitude and color differences in the standard andinstrumental uvby systems are given in tabular form.
|
Anomalous infrared emitters among A-type stars
Spectroscopic observations of a sample of 26 stars have been analyzed inthe blue and near-IR to find out if anomalous IR emitters (AIEs) have aspectral signature. It is found that many, but not all, such starsexhibit shell characteristics. Analysis of available IRAS photometricobservations of A-type stars shows that the detection of circumstellarfeatures depends strongly on the number of IR bands at which the objectwas observed. Out of the 707 stars observed by IRAS, 41 AIEs, or 5.7percent, are found. Among nonsupergiant AIEs, 23 percent show shellfeatures. The true percentage of AIEs among A-type stars is estimated tobe 1.5 percent in a volume-corrected sample. A list of 24 stars whichwere apparently not previously detected as AIEs is given.
|
Search for wide binaries in the Yale Bright Star Catalogue
A specific scheme for identifying wide binary candidates in the YaleBright Star Catalogue is presented. The choice of criteria for selectingcandidates is discussed, and the final criteria are used to compile apreliminary list of candidates which is presented and discussed. Thestatistics of the candidate list are characterized, and the list is usedto compute upper bounds on the wide binary density using a simpletheoretical model.
|
The early A type stars - Refined MK classification, confrontation with Stroemgren photometry, and the effects of rotation
The MK classification system for the early A-type stars is refined, anda parallel system of standards for the broad-lined stars is introduced.With this improved system, stars may be classified with significantlygreater precision than before. It is shown that spectral types in thissystem are not systematically affected by rotational line broadening. Atotal of 372 early A-type stars are classified, and a confrontation ofthese spectral types with Stroemgren photometry reveals a number ofsystematic photometric effects of rotation. In particular, high v sin istars are systematically redder than low v sin i stars of the samespectral type, and the beta index is weakened by rotation. It isconcluded that precise spectral classification in conjunction withStroemgren and H-beta photometry can potentially provide a valuablecheck and input to the theory of the atmospheres of rotating stars.
|
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.
|
Photographic observations of bright stars in the declination zone from +40 to +90 deg with a normal astrograph and 26-arcsec refractor at Pulkovo
Not Available
|
Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available
|
Photometric and astrometric observations of close visual binaries
The first photoelectric sequence for the magnitude differences of 215close visual binaries in the Johnson UBV and Stromgren uvby systems havebeen established. In addition, the position angle and the separation of140 stars were measured. Finally, for 134 stars, new photoelectricmeasurements of the combined integral brightness of both components inthe UBV and Stromgren systems were made. The measurements were carriedout using the area scanning technique.
|
Erratum - Discordances Between SAO and HD Numbers for Bright Stars
Not Available
|
Masses of red giants. I - Mean initial mass from visual binary data
Existing information on red-giant masses is reviewed, and an independentmethod for determining the frequency distribution of initial masses ofred giants is presented which is based on analysis of visual binarysystems containing a red giant and a main-sequence star (RG-MS systems).A list of RG-MS systems is compiled which yields an apparent frequencydistribution of the spectral types of the secondaries. This apparentdistribution is transformed to a 'true' distribution of secondary massesby accounting for certain selection effects; the true distribution isthen transformed into a distribution of initial primary masses (i.e.,initial masses of red-giant components) by assuming a form for thedistribution of mass ratios. Values in the range from 0.8 to 1.2 solarmasses and an upper limit of 1.4 solar masses are determined for themean initial masses of red giants and shown to be in satisfactoryagreement with the theoretical prediction of about 1 solar mass.
|
Photographic measures of double stars. II
Measures are presented for 302 double stars photographed on 657 plateswith the 36-in. Lick refractor in the period between 1945 and 1962. Thedata provided include the observing epochs, the rectangular coordinatesof the secondary components with reference to the respective primaries,the mean errors of a single measurement, the computed mean errors, thedouble-star separations, and the position angles both for the observingepoch and reduced to the equator of 2000. An additional 561 unmeasuredplates of acceptable quality obtained between 1948 and 1960 are listed.
|
Mass ratios of photographically unresolved visual binaries.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76...73F&db_key=AST
|
Mesures photographiques d'étoiles doubles
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..409F&db_key=AST
|
Short-Period Variability of b, a, and F Stars. III. a Survey of Delta Scuti Variable Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJS...19...79B&db_key=AST
|
Observations of the 21-CM Hydrogen Line Toward High-Latitude Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157.1101G&db_key=AST
|
The masses of stars above the main sequence.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969AJ.....74..689S&db_key=AST
|
UBV and narrow-band UVBY photometry of bright stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73...84B&db_key=AST
|
Observations of the Lithium Content of Stars in Visual Binary Systems
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966ApJ...145..759W&db_key=AST
|
Mouvement relatif linéaire d'étoiles doubles
Not Available
|
Interstellar Gas Near the Sun.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962ApJ...135..711M&db_key=AST
|
Double star measurements with a polarising micrometer.
Not Available
|
