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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
| Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
| On the HIPPARCOS photometry of chemically peculiar B, A, and F stars
The Hipparcos photometry of the Chemically Peculiar main sequence B, A,and F stars is examined for variability. Some non-magnetic CP stars,Mercury-Manganese and metallic-line stars, which according to canonicalwisdom should not be variable, may be variable and are identified forfurther study. Some potentially important magnetic CP stars are noted.Tables 1, 2, and 3 are available only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| An extensive Delta a-photometric survey of southern B and A type bright stars
Photoelectric photometry of 803 southern BS objects in the Deltaa-system as detection tool for magnetic chemically peculiar (=CP2) starshas been carried out and compared to published spectral types. Thestatistical yield of such objects detected by both techniques ispractically the same. We show that there are several factors whichcontaminate the search for these stars, but this contamination is onlyof the order of 10% in both techniques. We find a smooth transition fromnormal to peculiar stars. Our sample exhibits the largest fraction ofCP2 stars at their bluest colour interval, i.e. 10% of all stars in thecolour range -0.19 <= B-V < -0.10 or -0.10 <= b-y < -0.05.No peculiar stars based on the Delta a-criterion were found at bluercolours. Towards the red side the fraction of CP2 stars drops to about3% for positive values of B-V or b-y with red limits roughlycorresponding to normal stars of spectral type A5. The photometricbehaviour of other peculiar stars: Am, HgMn, delta Del, lambda Boo, Heabnormal stars, as well as Be/shell stars and supergiants shows someslight, but definite deviations from normal stars. Spectroscopic andvisual binaries are not distinguished from normal stars in their Delta abehaviour. The results of this work justify larger statistical work(e.g. in open clusters) employing more time-saving photometric methods(CCD). \newpage Based on observations obtained at the European SouthernObservatory, La Silla, Chile. This research has made use of the Simbaddatabase, operated at CDS, Strasbourg, France. Table 2 is only availablein electronic form via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| Behaviour of calcium abundance in Am-Fm stars with evolution
Calcium abundance in the atmosphere of Am stars is examined as afunction of their evolutionary state within the main sequence. Newspectroscopic abundances as well as abundances obtained photometricallyby Guthrie (1987) are used, since they are mutually quite consistent.The main result of this work is that, contrary to earlier suggestions,calcium abundance does not tend to be larger in evolved Am stars than inunevolved ones, for objects distributed along a given evolutionary trackin the HR diagram. The trend appears to be the reverse, if it is presentat all. For our whole sample of Am stars, there is a significantcorrelation between calcium abundance and effective temperature, in thesense that the cooler objects are the most Ca-deficient, hence have themost pronounced Am peculiarity. This implies an apparent correlationbetween calcium deficiency and age, although the lack of Am starsyounger than log t = 8.6 seems real. Our results are fully consistentwith the low rate of Am stars observed in young clusters and withtheoretical predictions of time-dependent radiative diffusion (Alecian1996). Based on observations collected at Observatoire de Haute Provence(CNRS), France, and on data from the ESA HIPPARCOS astrometry satellite.
| 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 second Quito astrolabe catalogue
The paper contains 515 individual corrections {DELTA}α and 235corrections {DELTA}δ to FK5 and FK5Supp. stars and 50 correctionsto their proper motions computed from observations made with theclassical Danjon astrolabe OPL-13 at Quito Astronomical Observatory ofEcuador National Polytechnical School during a period from 1964 to 1983.These corrections cover the declination zone from -30deg to +30deg. Meanprobable errors of catalogue positions are 0.047" in αcosδand 0.054" in δ. The systematic trends of the catalogue{DELTA}αalpha_cosδ,{DELTA}αdelta_cosδ,{DELTA}δalpha_, {DELTA}δdelta_ arepresented for the observed zone.
| Fifth fundamental catalogue. Part 2: The FK5 extension - new fundamental stars
The mean positions and proper motions for 3117 new fundamental starsessentially in the magnitude range about 4.5 to 9.5 are given in thisFK5 extension. Mean apparent visual magnitude is 7.2 and is on average2.5 magnitudes fainter then the basic FK5 which has a mean magnitude of4.7. (The basic FK5 gives the mean positions and proper motions for theclassical 1535 fundamental stars). The following are discussed: theobservational material, reduction of observations, star selection, andthe system for the FK5 extension. An explanation and description of thecatalog are given. The catalog of 3117 fundamental stars for the equinoxand epoch J2000.0 and B1950.0 is presented. The parallaxes and radialvelocities for 22 extension stars with large forecasting effects aregiven. Catalogs used in the compilation of the FK5 fundamental catalogare listed.
| MK morphology of AM stars
We present the results of an analysis of the spectra obtained for asample of 27 Am stars. We find evidence for the presence of groups amongthese stars and argue that all Am stars exhibit a pseudoluminosityeffect.
| MK morphological study of AM stars at 66 A/mm
The pseudoluminosity effect in the metallic line A-type stars found byAbt and Morgan (1976) is confirmed in a random sample of 27 Am stars.From a morphological study of their spectra in the wavelength interval3850-4400 A at a reciprocal dispersion of 66 A/mm, revised spectraltypes are given on the MK system for their K-line and metallic-linespectra. This shows that: (1) the segregation of weak Am from the Amstars largely agrees with that by Cowley et al. (1969); (2) all thestars in the sample are dwarfs according to their K-line classification;(3) more than 80 percent exhibit the pseudoluminosity effectsignificantly, with their metallic-line spectra resembling a giant oreven a supergiant in the violet (3850-4100 A), and a giant rather than adwarf in the blue region (4260-4400 A); and (4) in two-thirds of thestars under (3), the Sr II 4077 A line is found to have a markedlybrighter luminosity class compared to any region, and in more thanone-third of the sample it is comparable to that in Ap stars. Moreover,at least five stars exhibit characteristics which might suggest aspectrum variability; among these, the most striking example is 41 SexA. The metallic-line spectra of another five stars appear to be similarto A-shell type in different degrees. Less than 20 percent of the samplecomprises stars which do not show any significant differentialluminosity effect; these stars might have been misclassified or perhapsthey are in a quiescent state.
| Abundances of calcium for a sample of 57 classical AM stars
Abundances of calcium, log N(Ca), are derived for a fairly completesample of 57 single-lined classical Am stars. Published photoelectricmeasures of the CaII K-line at 3933 A and K-line spectral types are usedto determine the equivalent widths of the K-line for a differentialcurve-of-growth comparison of the Am stars with the standard stars 15Vul and 28 And. On a scale with log N(H) = 12.0, the values of log N(Ca)for the Am stars range from 5.5 to 6.5, the solar value being 6.36. TheAm stars with low abundances of calcium have a small range of themodified age parameter, and absolute magnitudes within about 1.3 mag ofthe zero-age main sequence, whereas the other Am stars and normal starshave a larger spread in age. These results are probably consistent withthe suggestion that the Am phenomenon is due to subphotosphericseparation of elements by diffusion in slowly rotating A-type stars.
| Rotation velocities of metallic-line stars
The rotation velocities (V sin i) of 81 Am stars were determined usingspectra of dispersion 15 A/mm. The profiles of Fe I 4045 A and Sr II4215 A lines were compared with the computed profiles. The line widthand its ratio to the central depth are found to be most sensitive to therotation velocity. The hydrogen spectral types obtained from the H-gammaequivalent width are also given. It is noted that the extremal Am starHR 4646 has a relatively high rotation velocity of at least 70 km/s.
| Results from the occultation of 14 PISCIUM by (51) NEMAUSA
Observations of the September 11, 1983 occultation of 14 Psc by theasteroid (51) Nemausa were obtained at six sites distributed across thenorthern two-thirds of the track. The observations are well representedby an elliptical limb profile with a semimajor axis of 84.9 + or - 2.0km and oblateness (1-b'/a') 0.20 + or - 0.05. The mean radius of 74 + or- 4 km agrees with the 1979 occultation effective radius of 76.5 + or -4 km and the published radiometric radius of 75.5 km (Morrison andZellner, 1979).
| Occultation of 14 PISCIUM by (51) NEMAUSA on 1983 Sept. 11
IAUC 3834 available at Central Bureau for Astronomical Telegrams.IAUC 3834 available at Central Bureau for Astronomical Telegrams.
| Occultation of 14 Piscium by (51) Nemausa.
Not Available
| Occultation of 14 Piscium by (51) NEMAUSA on 1983 Sept. 11.
Not Available
| Lists of photometric AM candidates
The Geneva photometric m parameter (Nicolet and Cramer, 1982) is used inorder to select Am photometric candidates from the Rufener (1981)catalogue. Two lists are given, the first containing field stars and thesecond cluster stars. According to the photometric criteria thediffusion process probably responsible for the Am phenomenon takes placerather quickly as Am candidates are present in young clusters. It isconfirmed that the phenomenon is enhanced by low rotational velocity andhigh metallicity. The age seems to slightly affect the Am phenomenon.
| An improved position of 14 PISCIUM
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983A&A...124L...7B&db_key=AST
| Properties of Am, Delta Del and Delta SCT stars in the VBLUW system
The spread with respect to the main sequence in the two-color diagramsfor 115 Am, Delta Del and Delta Sct, for which VBLUW photometricobservations have been obtained, is primarily attributed to gravityeffects. Exceptions to this rule can be recognized from a comparison oftheir positions in these diagrams and in the reddening-independentdiagram L-U/B-L, where some Delta Sct stars have experienced relativelyhigh reddenings, while others are presumably metal-poor. It is notedthat gravities and temperatures compare satisfactorily with those ofDavis Philip et al. (1976), which were based on uvby-beta photometry.
| The Hyades main sequence
Intermediate band, H-beta and RI observations of 72 Hyades cluster starsto V = 11 mag are reported and discussed. A modulus of 3.2 mag isderived on the basis of a comparison with field stars of large parallax.Also presented are observations of 98 main-sequence stars of the Hyadesgroup that were previously found to be group members from kinematicalconsiderations. Parallaxes of the group stars, computed on theassumption that they are members of an extended Hyades cluster, yieldmean values of (U, V, W) = (+40.5, -18.4, -4.9) km/s, with dispersionsof (2.3, 2.3, 6.0) km/s, compared with (+41.7, -18.4, -2.0) and (2.6,1.3, 1.9) km/s for the brightest cluster members. It is noted that allthe stars discussed can be considered as members of a supercluster inwhich only a slight relaxation control of the W velocities is presentfor stars far from the nucleus. Evidence is found, including that of thePraesepe cluster at Z = +80 pc, for some interchange between the U, V,and W velocities in stars farthest from the galactic plane, with thetotal cluster velocity being maintained.
| UV photometric data on standard A, F and AM stars observed by S2/68
Data derived from the stellar UV fluxes of the S2/68 experiment andanalyzed and interpreted by Van't Veer et al. (1980) are presented.There are two tables of photometric data. One lists all standard stars,without exception, belonging to the intersection of the following threecatalogs: (1) the Thompson et al. (1978) catalog of S2/68 fluxes; (2)the PMR catalog (Philip et al., 1976), which is an analysis of theHauck-Mermilliod catalog (1975) of homogeneous four color data; and (3)the Crawford and Barnes (1970) list of standard stars for uvbyphotometry. The other table lists all the Am stars, without exception,belonging to the intersection of the following three catalogs: (1)Thompson et al. (1978); (2) PMR (1976); and (3) the Hauck (1973) catalogof the Am stars.
| The absolute magnitude of the AM stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&A....93..155G&db_key=AST
| Catalog of profiles and equivalent widths of the CA II K line in the spectra of metallic-line stars
Profiles of the Ca II K line for 87 bright Am, A, and F stars weremeasured on spectrograms with a dispersion of 15 A/mm. Halfwidths of theprofiles for fixed values of line depth, central depths, and equivalentwidths are presented. In contrast to the case of peculiar stars, theobserved K-line profiles in the metallic-line stars do not show anypeculiar structure.
| Properties of AM stars in the Geneva photometric system
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....92..289H&db_key=AST
| The rotational velocity effect on the main sequence AM stars metallicity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979A&A....74...38B&db_key=AST
| Metallicism and pulsation - The marginal metallic line stars
Evidence is presented that HR 4594 and HR 8210 are pulsating marginal Amstars. It is suggested that (1) classical Am stars do not pulsate, (2)evolved Am stars may pulsate, and (3) marginal Am stars may pulsate. Itis further suggested that, within the Am domain, temperature, age,rotation, and pulsation are sufficient to determine whether a star willbe Am, marginal Am, or spectrally normal.
| UBVRI photometry of 225 AM stars
UBVRI photometry of 225 Am stars taken from Mendoza's (1974) catalog ispresented. The results are compared with those obtained by Feinstein(1974) for 21 of the stars and with the values of Johnson et al. (1966).It is assumed that in the first approximation the (V-I) color index ofan unreddened Am star is equal to that of a normal main-sequence star; astandard main sequence is defined for A and early F stars, and thefive-color photometry is analyzed by means of plots of U-V vs. V-I, B-Vvs. V-I, and V-R vs. V-I. Mean color deficiencies of Am stars areexamined, and it is suggested that an unreddened star located below themain-sequence A0-F2 line in the (V-I, U-V) plane is a photometric Amstar. It is concluded that: (1) photometric Am stars have colordeficiencies (as a function of V-I) which, on the average, are 0.07 magin (U-V) color index and 0.025 mag in (B-V) color index; (2) Am starswith V-R less than 0.25 mag may also have a color deficiency of about0.01 mag; (3) Am stars with V-R greater than 0.3 mag may have a colorexcess of approximately 0.01 mag; and (4) Am stars with V-R between 0.25and 0.3 mag may have normal colors.
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| Takýmyýldýz: | Baliklar |
| Sað Açýklýk: | 23h34m09.00s |
| Yükselim: | -01°14'51.0" |
| Görünürdeki Parlaklýk: | 5.87 |
| Uzaklýk: | 70.572 parsek |
| özdevim Sað Açýklýk: | 107.1 |
| özdevim Yükselim: | -13.2 |
| B-T magnitude: | 6.258 |
| V-T magnitude: | 5.91 |
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