Contents
Images
Upload your image
DSS Images Other Images
Related articles
Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| 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
| An improved ephemeris and physical elements of ER Vul
New photoelectric U B{V} and BV RI observations, secured duringAugust-November of 2002 at two observatories distant in local time areanalyzed together with two earlier photometric data sets and allavailable radial velocities to derive the most accurate ephemeris of thebinary and to set limits on its basic physical elements. Theseobservations were obtained as a support for a high-dispersionspectroscopic study, results of which will be published separately. Itwas found that radial velocities and photometric observations spanning53 years can be reconciled with the linear ephemeris T_prim.min.=HJD 2440 182.25628(46) + 0698095113(29)d × E, where the rms errors ofthe last digits are given in brackets. Masses of the stars are 1.02 \fmsand 0.97 \fms and the binary separation is 4.170 Rȯ.There is still a large uncertainty in the stellar radii. We also reportthe discovery of rapid light variations on a time scale of hours seen inthe U band light curve and offer a few thoughts on the futureinvestigation of this binary.This research is based on photoelectric observations from Hvar andUniversity of Victoria Observatories.Table 4 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/415/289
| Photoelectric Observations of the Eclipsing Variable ER Vulpeculae
Not Available
| The Photometric Observations of ER Vulpeculae: Photometric Analysis with the W-D Code
Not Available
| 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 active close binary system ER Vulpeculae
UBV (RI)c photometry of the short period RS CVn binary ERVul, gathered in the years 1990-1992, is analyzed. A set of binarysystem parameters is finally derived with some confidence, after duetests and comparisons with literature values. The well-knownirregularities of ER Vul are interpreted largely in terms of darkmaculae, whose major characteristics (size, surface position) arequantified. The occurrence of at least one bright spot (facula) is alsoevidenced, however. The maculation representation is shown to beconsistent with a 'quasi-poloidal' spot distribution - high latitudespot concentrations tending to be roughly symmetric in both hemispheres.This model requires further observational checking.
| The Light Curve of ER Vulpeculae
Not Available
| 1988 and 1989 BV Photometry of ER Vul
Not Available
| ER Vulpeculae
IAUC 5329 available at Central Bureau for Astronomical Telegrams.
| UBV photometry of ER Vulpeculae
UBV photometry of the RS CVn-type eclipsing binary system ER Vulpeculaehas been presented. The period comes out to be 0.698093d. The averagedepths of primary and secondary minima are, respectively, 0.21 and0.12m. The colors at various phases have been given. A dip is seenaround phase 0.73P as was seen in the observations of Arevalo et al.(1988). Large scatter is present in the observations as noticed earlier,and may be due to activity of the components.
| Time-scale variability of the light curves of ER Vulpeculae
An efficient procedure for analyzing the variability of light curves ofsolar type eclipsing binaries has been implemented. By means of thisprocedure the UBV photoelectric light curves of ER Vul, observed in1985, have been studied and three sinusoidal waves, which could explainboth the short and the long time-scale variability, have been identifiedthrough the distortion of the light curves. A tentative interpretationis given to link these waves to the stellar activity.
| Photometric variability in chromospherically active stars. III - The binary stars
Differential UBV photometry of 49 late-type chromospherically activebinary stars has been obtained. A total of 12,353 differential UBVmagnitudes have been acquired and are used to determine seasonalphotometric periods, amplitudes, mean brightnesses, maximum spotamplitudes, 'unspotted' differential magnitudes, and times of minimumlight. Standard Fourier techniques are used to investigate the cause ofthe light variability. Eight stars are found which exhibit lightvariations due not to spot activity but rather to ellipticity and/orreflection effect. Others show combinations of all three effects. Someof the systems also show substantial differences between theirrotational and orbital period.
| Photometric study of ER VUL
Simultaneous UBVRI and infrared JHKL light curves of the short-period RSCVn system ER Vul are presented, and both the mean level and depths ofeclipses are studied. Some peculiar features, present in the lightcurves over time are pointed out, which are frequently shown by other RSCVn short-period systems at about the same phase values, suggesting acommon origin. It seems difficult, however, to reconcile the usualinterpretation based on the presence of starspots with the observed timevariations at the mean level and depth of the eclipses. The photometriccolors indicate ultraviolet and infrared excesses which seem tooriginate in hot circumstellar matter.
| B, V Photometry of ER Vulpeculae
Not Available
| Light curve variations in ER Vulpeculae
Photoelectric observations of the peculiar eclipsing variable ER Vulwere obtained in blue and yellow light, in the 1981 and 1982 observingseasons. The light curves undergo change in short time intervals. Thewavelike distortion superimposed on the light curves is clearly seen,but sometimes there is no indication of its existence. The migrationperiod has been estimated roughly about eight months. Moreover,small-amplitude light fluctuations in the light curves are noticeable.These variations seem to occur randomly. When the IUE and opticalobservations are taken into consideration together, it is stronglysuggested that both of the components in the system ER Vul are tooactive.
| 1981 UBVR Photometric Observations of ER Vul
Not Available
| The fourth meridian catalog of Besancon Observatory
The catalog presented gives differential meridian positions for 670F-type stars between plus 15 and plus 45 deg declination. The positionsare reduced to the equinox of 1950.0 without proper motions; 333 FK4stars were used as reference stars. A minimum of three and an average offive transits of each program star were observed photoelectrically usinga Gautier transit circle and a Hog grid. The internal accuracy ofindividual measurements is shown to range from 0.013 sec in rightascension and 0.30 arcsec in declination for brighter stars under betterobserving conditions to 0.020 sec in right ascension and 0.38 arcsec indeclination for fainter stars under worse conditions. The standarderrors were applied to compute weighted mean positions, mean epochs, andunweighted means for the program stars. Mean corrections for 283 FK4stars are also provided.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Fuchs |
| Right ascension: | 21h01m41.67s |
| Declination: | +28°06'05.0" |
| Apparent magnitude: | 7.765 |
| Distance: | 83.264 parsecs |
| Proper motion RA: | 9 |
| Proper motion Dec: | -39 |
| B-T magnitude: | 8.297 |
| V-T magnitude: | 7.809 |
Catalogs and designations:
|
