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δ Ser (Tsin)



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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.

Kinematics of Hipparcos Visual Binaries. II. Stars with Ground-Based Orbital Solutions
This paper continues kinematical investigations of the Hipparcos visualbinaries with known orbits. A sample, consisting of 804 binary systemswith orbital elements determined from ground-based observations, isselected. The mean relative error of their parallaxes is about 12% andthe mean relative error of proper motions is about 4%. However, even 41%of the sample stars lack radial velocity measurements. The computedGalactic velocity components and other kinematical parameters are usedto divide the stars with known radial velocities into kinematical agegroups. The majority (92%) of binaries from the sample are thin diskstars, 7.6% have thick disk kinematics and only two binaries have halokinematics. Among them, the long-period variable Mira Ceti has a verydiscordant {Hipparcos} and ground-based parallax values. From the wholesample, 60 stars are ascribed to the thick disk and halo population.There is an urgent need to increase the number of the identified halobinaries with known orbits and substantially improve the situation withradial velocity data for stars with known orbits.

Speckle Observations of Composite Spectrum Stars with PISCO in 1993-1998
We present speckle interferometry observations of 47 composite spectrumstars obtained between 1993 and 1998 at the Pic du Midi Observatory withthe PISCO speckle camera. 76% of over 150 independent 10 minutesequences of observations led to a companion detection. Binary componentangular separations ranged from 0.05" to 1.2". We also obtained a seriesof 23 measurements of an additional nine close binaries. PISCOobservations confirm, for the first time since their discovery, theduplicity of HD 29104 (L4), HD 83808 (WGT 1Aa), HD 183912 Aa' (BON Ap),and HD 156729 (HR 6436). Discovered as double by Hipparcos, theparticularly difficult to resolve HD 156729 was observed despite thelarge magnitude difference, Δm=4.2, between its two components.Based on observations made with the Télescope Bernard Lyot at Picdu Midi Observatory, France.

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 ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897

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 ( or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521

Dating Ptolemy's star catalogue through proper motions : the Hipparchan epoch.
Not Available

Speckle Interferometry at the US Naval Observatory. VI.
The results of 1068 speckle interferometric observations of doublestars, made with the 26 inch (0.66 m) refractor of the US NavalObservatory, are presented. These observations are averaged into 841means of 815 binary stars. The systems range in separation from 0.22" to6.01" with a mean separation of 2.21" and have a limiting secondarymagnitude of V=12.5. This is the sixth in a series of papers presentingmeasures obtained with this system, and it covers the period 1999January 1 through 2000 January 9.

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 ( or viahttp://cdsweb.u-strasbg.fr/Abstract.html

Speckle Interferometry at the US Naval Observatory. IV.
The results of 1314 speckle interferometric observations of 625 binarystars, ranging in separation from 0.2" to 5.2" with a limiting secondarymagnitude of V=11, are tabulated. These observations were obtained usingthe 66 cm refractor at the US Naval Observatory in Washington, DC, withan intensified CCD detector. This is the fourth in a series of paperspresenting measures obtained with this equipment and covers the period1997 January 1 through December 31. Random errors for all measures areestimated to be 18 mas in separation and 0.57d/rho in position angle,where rho is the separation in arcseconds.

CCD and micrometric observations of visual double stars
Relative positions and separations for 65 visual binaries are given. CCDframes were taken at the 1-m coudetelescope and micrometric observationswere carried out at the 65-cm refractor, both at the Venezuelan NationalObservatory. The visual double stars observed were selected from theRamon Maria Aller Observatory program list. In addition, we alsoobserved several long period double stars with poorly determined orbitalelements.

Measurements of double stars 1993.67 - 1998.13
624 Micrometer Measurements of 224 pairs with a 32.5 cm Cassegrain, 719Measurements of 310 double stars with a 360 mm Newtonian are given.Tables 1 to 4 are available in electronic form only at the CDS130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html

Luminosity and related parameters of δ Scuti stars from HIPPARCOS parallaxes. General properties of luminosity.
The absolute magnitudes of δ Scuti stars derived from parallaxesmeasured by the Hipparcos astrometric satellite are discussed andcompared with the previous estimates based on photometric uvbyβindices. There are significant differences which are related tophotometric effects of metallicity and rotational velocity, but thepossible effect of a close companion on the measured apparent magnitudeshould be also taken into account. The possibility of differentgroupings of δ Scuti stars based on the absolute magnitudes isbriefly discussed. Some high amplitude δ Scuti stars withintermediate or normal metallicity and small and uncertain parallax haveapparently a very low luminosity; this could be a systematic effectrelated to the observational errors.

Micrometer observations of double stars from the Fabra Observatory
The 38-cm refractor at the Fabra Observatory in Spain was used to obtain150 micrometer observations of 61 double stars. In tabular form, eachstar is listed by its WDS number, the letters of its components (ifmultiple), its ADS number, the observation epoch, the observed positionsangle, and the angular distance between the components. For the multipleobservations, in no case did the averaged measurements differ by morethan 3 deg for positions or 0.10 arcsec for angular separations.

Orbital binaries with variable components
Published observational data are compiled for 171 binary systems forwhich (1) orbital parameters have been computed and (2) one or bothcomponents are known or suspected to exhibit intrinsic variability. Theselection criteria for the catalog are discussed; the data are presentedin a large table; and brief notes on the unusual characteristics ofspecific binaries are provided.

Photometric study of the delta Scuti star delta Serpentis.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987RMxAA..14..419R&db_key=AST

Pulsation Periods in delta Serpentis
Not Available

Spectral Estimation of Luminosity and Other Characteristics of the delta Scuti Stars AI CVn (= 4 CVn) and delta Ser
Not Available

Micrometer measurements of visual double stars (3rd list)
Not Available

The magnesium method for determining the electron density in stellar atmospheres
A method for determining the electron density in stellar atmospheres byusing the ultraviolet resonance lines of neutral and ionized magnesium,2852-A Mg I and 2795-A Mg II, is briefly described. The mean electrondensities in the atmospheres of 31 type A0-G5 stars as well as the sun,which have been determined by using equivalent widths of the 2852-A and2795-A lines recorded in experiments on the Orion 2, IUE, and otherspacecraft, are presented.

The Measurements of Double Stars with the Polarizing Micrometer - Part Ten
Not Available

Infrared observations of Beta Cephei and Delta Scuti stars
We have made near-infrared photometric observations of nine Beta-Cepheiand eight Delta-Scuti stars in J, H, and K bands. The observed fluxesare in good agreement with those expected according to their spectraltypes. It is concluded that these stars do not have any anomalousemission in these near-infrared bands.

Visual Double Stars for the Amateur
Not Available

Double star observations made with the 28-inch refractor 1963-1970.
Not Available

On the Period-Luminosity Relation of the delta Scuti Stars
Not Available

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Observation and Astrometry data

Right ascension:15h34m48.10s
Apparent magnitude:3.8
Distance:64.35 parsecs

Catalogs and designations:
Proper NamesTsin
Bayerδ Ser
Flamsteed13 Ser
HD 1989HD 138917
USNO-A2.0USNO-A2 0975-07886623
BSC 1991HR 5788

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