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λ Cnc (Kwan Wei)


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Rotational Velocities of B Stars
We measured the projected rotational velocities of 1092 northern B starslisted in the Bright Star Catalogue (BSC) and calibrated them againstthe 1975 Slettebak et al. system. We found that the published values ofB dwarfs in the BSC average 27% higher than those standards. Only 0.3%of the stars have rotational velocities in excess of two-thirds of thebreakup velocities, and the mean velocity is only 25% of breakup,implying that impending breakup is not a significant factor in reducingrotational velocities. For the B8-B9.5 III-V stars the bimodaldistribution in V can be explained by a set of slowly rotating Ap starsand a set of rapidly rotating normal stars. For the B0-B5 III-V starsthat include very few peculiar stars, the distributions in V are notbimodal. Are the low rotational velocities of B stars due to theoccurrence of frequent low-mass companions, planets, or disks? Therotational velocities of giants originating from late B dwarfs areconsistent with their conservation of angular momentum in shells.However, we are puzzled by why the giants that originate from the earlyB dwarfs, despite having 3 times greater radii, have nearly the samerotational velocities. We find that all B-type primaries in binarieswith periods less than 2.4 days have synchronized rotational and orbitalmotions; those with periods between 2.4 and 5.0 days are rotating withina factor 2 of synchronization or are ``nearly synchronized.'' Thecorresponding period ranges for A-type stars are 4.9 and 10.5 days, ortwice as large. We found that the rotational velocities of the primariesare synchronized earlier than their orbits are circularized. The maximumorbital period for circularized B binaries is 1.5 days and for Abinaries is 2.5 days. For stars of various ages from 107.5 to1010.2 yr the maximum circularized periods are a smoothexponential function of age.

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

Intrinsic Energy Distribution in Stellar Spectra in the Wavelength Interval 320--760 NM
The intrinsic energy distributions in the interval 320--760 nm ofspectral types B5--G8 of luminosity V, F0--F5 of luminosity IV andG8--M2 of luminosity III, determined by authors, are intercompared withthe catalogue of the mean energy distribution data published bySviderskiene (1988).

On the normal energy distribution in stellar spectra: Main-sequence B stars
Not Available

The ROSAT all-sky survey catalogue of optically bright OB-type stars.
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.

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.

Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.

UBV photometry of stars whose positions are accurately known. VI
Results are presented from UBV photometric observations of 1000 stars ofthe Bright Star Catalogue and the faint extension of the FK5.Observations were carried out between July 1987 and December 1990 withthe 40-cm Cassegrain telescope of the Kvistaberg Observatory.

Behaviour of OI triplet 7773 A. II - AP stars
The behavior of the O I triplet at 7773 A in a sample of 74 Ap stars isanalyzed and compared with the results derived for a set of 50 normalstars. These abundance determinations are made in the NLTE frame byintroducing a correction to the LTE model atmosphere. Among the Apstars, the oxygen abundance varies greatly from one group to another andshows a clear separation between the different classes of peculiarities.An underabundance of up to a factor 400 is found for the (Sr-Cr-Eu)stars.

Behaviour of O I triplet Lambda-7773
Reticon spectra of the O I triplet at 7772-7775-Lambda are analyzed in67 non-peculiar B to F stars. The dependence of the equivalent width ofthe triplet on luminosity, but also on other atmospheric parameters isexamined; predicted intensities are compared with the observed ones andthe effects of microturbulence and NLTE are discussed.

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.

Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available

The A0 stars
A photometric grid, standardized on MK spectral standards, has been usedto compare spectral types and luminosity classes obtainedphotometrically with those in two extensive spectral surveys coveringthe entire sky. Major discrepancies include the spectroscopicclassification of B9.5, which may indicate an otherwise unrecognizedspectral peculiarity, a different A0/A1 spectral type boundary in thetwo samples involved, the well-known misclassification of weak heliumstars, and an appreciable percentage of stars which are called dwarfsspectroscopically but are of higher photometric luminosity. The spacemotion vectors of these stars for which radial velocities are available,and excluding the minimum of 25 percent that are spectroscopic binarieswithout orbital elements, show structure in their distribution in the(U, V)-plane, with members of the Local Association and the Hyades andSirius superclusters forming obvious concentrations. The members of theLocal Association in the samples are mainly old (more than 200 millionyears) mode A stars, although a few much younger stars are included. Themembers of the Hyades and Sirius superclusters contain many bluestragglers, including several peculiar stars of the Hg, Mn, and Sivarieties.

Spectrophotometry of peculiar B and A stars. XVI - The derivation of indices by fitting the Balmer and Paschen continua of the normal stars and application to the mercury-manganese stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1984A&AS...55..479A&db_key=AST

Picture gallery - A structured presentation of OAO-2 photometric data supported by OAO-2 spectrophotometric data and UBV, ANS and TD1 observations
Graphs are presented for the stellar fluxes of 531 stars in the5500-1330 A wavelength range, which have been divided into 52 categorieson the basis of spectral types. The merging of medium band interferencefilter photometry, UBV photometry, ANS photometry and TD1 fluxes, aswell as the ordering of the objects, should prove helpful in studies ofinterstellar reddening, luminosity effects, bandwidth effects, andcomparisons with model stellar atmospheres. The agreement between thevarious UV photometric systems for early-type stars is generally betterthan 0.10 mag. A list of stars whose photometric properties indicatestellar or interstellar anomalies is also provided.

Field population II blue stragglers
Photometry and high-resolution spectra of metal-poor stars hotter thanthe turn-off of globular clusters are presented and discussed. It isshown that the number of field stars that are Population II stragglersis extremely small, with only two (BD +25 deg 1981 and BD -12 deg 2669)which are brighter than V = 12, not variable, and have metallicitiesless than one-tenth solar. The distribution of their abundances of theCNO elements and Al, Mg, Sr, and Ba, with respect to the iron peak, veryclosely resemble that of the metal-poor field stars of turn-offtemperatures. Radial velocities ruled out a short-period binary in thecase of BD -12 deg 2669, and argue against it in BD +25 deg 1981. Inaddition, no evidence is found for or against wide pairs, mass transfer,recent formation, or prolonged main-sequence lifetimes as the reason forthe stragglers' existence.

Ultraviolet photometry from the Orbiting Astronomical Observatory. XXXIV - Filter photometry of 531 stars of diverse types
Ultraviolet magnitudes for 531 stars observed with the WisconsinExperiment Package on OAO 2 are tabulated. It is noted that these dataconstitute a subset of the OAO 2 data on file at the National SpaceScience Data Center. The tabulation contains previously published dataall reduced to a uniform magnitude system. It is pointed out that theobservations were obtained with the medium band interference filterphotometers. Eleven magnitudes are given designated by their centroidwavelengths.

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

Photometric studies of stars in ORI OB1 /belt/
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84.1846G&db_key=AST

Spectrophotometry of peculiar B and A stars. III - 21 Persei, 56 Arietis, and 49 CANCRI
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979AJ.....84.1726A&db_key=AST

Spectrophotometry of peculiar B and A stars. I - On the detection of the lambda 4200 and lambda 5200 broad, continuum features of peculiar A stars
Photometric indices are used to study the broad continuum features thatare present in the energy distributions of many peculiar A stars andthat may be indicators of the atmospheric structure. Indices derivedfrom representative or averages of spectrophotometric scans areconsidered. Values of Maitzen's (1976) delta-a index - a measure of thelambda 5200 feature - are synthetized from spectrophotometric data. Twoother specific indices are calculated from spectrophotometry to measurethe strength of lambda 4200 feature. The details of the photometricvariability are presented with the data. Possible effects of thevariability on the conclusions made are discussed.

Spectrophotometry of B, A, and F stars
Energy distributions of 33 normal B, A, and F stars for wavelengths3300-7100 are given that are consistent with the Hayes-Lathamcalibration of Vega. The derived upper limit on the photometric accuracyusing a comparison of observed and synthetic u-b and b-y indices is0.010 mag and 0.008 mag, respectively. Effective temperatures foundusing empirical calibrations agree with those derived using fullyline-blanketed model atmospheres. Effective temperatures are found forselected spectral types.

Is star formation bimodal ? II. The nearest early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..187E&db_key=AST

Infrared radiation of planetary nebulae. II. New and revised observations at 1.0-2.5 μ
Not Available

Rotational Velocities of a0 Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..101D&db_key=AST

Observations of occultations of stars by the moon
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..395H&db_key=AST

Ultraviolet photometry from the orbiting astronomical observatory. VIII. The blue AP stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...185..577L&db_key=AST

Four-color and Hβ photometry for the brighter AO type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..109C&db_key=AST

A catalogue of proper motions for 437 A stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..189F&db_key=AST

Photoelectric observations of early A stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..165J&db_key=AST

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Observation and Astrometry data

Constellation:Cancer
Right ascension:08h20m32.10s
Declination:+24°01'20.0"
Apparent magnitude:5.98
Distance:128.535 parsecs
Proper motion RA:-20.6
Proper motion Dec:-18.3
B-T magnitude:5.852
V-T magnitude:5.904

Catalogs and designations:
Proper NamesKwan Wei
  (Edit)
Bayerλ Cnc
Flamsteed19 Cnc
HD 1989HD 70011
TYCHO-2 2000TYC 1928-1817-1
USNO-A2.0USNO-A2 1125-05591171
BSC 1991HR 3268
HIPHIP 40881

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