Ýçindekiler
Görüntüler
Resim Yükleyin
DSS Images Other Images
Ýlgili Makaleler
On-line database of photometric observations of magnetic chemically peculiar stars
We present our extensive project of the On-line database ofphotometric observations of magnetic chemically peculiar stars tocollect published data of photometric observations of magneticchemically peculiar (mCP) stars in the optical and near IR regions. Nowthe nascent database contains more than 107 000 photometric measurementsof 102 mCP stars and will be continually supplemented with published ornew photometric data on these and about 150 additional mCP stars. Thisreport describes the structure and organization of the database.Moreover, for the all included data we estimated the error ofmeasurements and the effective amplitudes of the light curves.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| Radial velocities, rotations, and duplicity of a sample of early F-type dwarfs
We present new radial and rotational velocities for 595 nearby early Fdwarfs, based on digital spectra cross-correlated with individuallyoptimised synthetic template spectra. The selection of optimumtemplates, the determination of rotational velocities, and theextraction of velocities from the blended spectra of double-linedspectroscopic binaries are discussed in some detail. We find 170spectroscopic binaries in the sample and determine orbits for 18double-lined and 2 single-lined binaries, including some spectroscopictriples. 73 stars are listed with too rapid rotation to yield usefulradial velocities (i.e. v sin i > 120 km~s^-1). We discuss the binaryfrequency in the sample, and the influence of unrecognised binaries onthe definition of clean metallicity groups of young F dwarfs and thedetermination of their kinematical properties. Tables 1, 5 and 6 areonly available, and Tables 2-4 also available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
| Stroemgren photometry of F- and G-type stars brighter than V = 9.6. I. UVBY photometry
Within the framework of a large photometric observing program, designedto investigate the Galaxy's structure and evolution, Hβ photometryis being made for about 9000 stars. As a by-product, supplementary uvbyphotometry has been made. The results are presented in a cataloguecontaining 6924 uvby observations of 6190 stars, all south ofδ=+38deg. The overall internal rms errors of one observation(transformed to the standard system) of a program star in the interval6.5
| The 69th Name-List of Variable Stars
Not Available
| The determination of the rotational periods of rapidly oscillating AP stars from their mean light variations. I - The rapidly oscillating AP star, HD 6532; the F2 IV/V star, HD 6491; and the He-weak B star, HD 5737 (HR 280, Alpha Scl
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987MNRAS.228..141K&db_key=AST
| A frequency solution to the light variations in the rapidly oscillating AP star HD 6532 - Evidence for an L = 1 oblique dipole oscillation
A frequency analysis of 90 hr of high-speed photometric data of the Apstar HD 6532 obtained in 1985 shows the presence of three principalfrequencies (f1 = 2.396212 + or - 0.000002 mHz, f2 = 2.402164 + or -0.000002 mHz, and f3 = 2.408116 + or - 0.000003 mHz) which are equallyspaced by 5.952 + or - 0.004 microHz. No further evidence of the 1.17mHz peak seen in the amplitude spectra of Kurtz and Kreidl (1985) in1984 is found. The separations of the frequencies of the f123 frequencytriplet are found to be equal to the rotation frequency derived by Kurtzand Marang (1987), and f123 is interpreted as an oblique dipoleoscillation within the oblique pulsator model. Constraints are placed onsome of the parameters of the oblique pulsator model, and the form andephemeris of as-yet unobserved magnetic variations are predicted.
| A survey of trigonometric parallaxes and proper motions with the UK Schmidt telescope. II - Astrometric and photometric data for a complete sample of 6125 stars brighter than B = 17.5, V = 17.0 in the South Galactic CAP
Abstract image available at:http://adsabs.harvard.edu/abs/1986MNRAS.223..629M
| A frequency analysis of a newly discovered rapidly oscillating AP star, HD 6532
The authors have discovered rapid oscillations in the Ap star, HD 6532.A frequency analysis of 44 hr of observations obtained on 10 nights in1984 from both CTIO and SAAO is presented. A frequency triplet is foundwith periods near 6.94 min which does not appear to be equally spaced.Aliasing problems prevent any definitive conclusion, however. Theauthors also claim to have detected a 14.28-min oscillation on twonights, although this needs confirmation. HD 6532 shows mean lightvariations with a period of 0.8929 day. Based on plausibility argumentsabout the rotational velocity of Ap stars, it is suggested that therotational period of HD 6532 is Prot = 1.7858 day so that itshows a double wave mean light curve. This implies that it should show apolarity reversing magnetic field.
|
Yeni bir Makale Öner
Ýlgili Baðlantýlar
Yeni Bir Baðlantý Öner
sonraki gruplarýn üyesi:
|
Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 01h05m34.59s |
| Yükselim: | -26°57'18.5" |
| Görünürdeki Parlaklýk: | 8.136 |
| Uzaklýk: | 152.905 parsek |
| özdevim Sað Açýklýk: | -2.1 |
| özdevim Yükselim: | -48.6 |
| B-T magnitude: | 8.571 |
| V-T magnitude: | 8.172 |
Kataloglar ve belirtme:
|
INHABITED SKY
