Contenidos
Imágenes
Subir su imagen
DSS Images Other Images
Artículos relacionados
Photometry of symbiotic stars. XI. EG And, Z And, BF Cyg, CH Cyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AR Pav, AG Peg, AX Per, QW Sge, IV Vir and the LMXB V934 Her
We present new photometric observations of EG And, Z And, BF Cyg, CHCyg, CI Cyg, V1329 Cyg, TX CVn, AG Dra, RW Hya, AG Peg, AX Per, IV Virand the peculiar M giant V934 Her, which were made in the standardJohnson UBV(R) system. QW Sge was measured in the Kron-Cousin B, V,RC, IC system and for AR Pav we present its newvisual estimates. The current issue gathers observations of theseobjects to December 2003. The main results can be summarized as follows:EG And: The primary minimum in the U light curve (LC) occurred at theend of 2002. A 0.2 -- 0.3 mag brightening in U was detected in theautumn of 2003. Z And: At around August 2002 we detected for the firsttime a minimum, which is due to eclipse of the active object by the redgiant. Measurements from 2003.3 are close to those of a quiescent phase.BF Cyg: In February 2003 a short-term flare developed in the LC. Adifference in the depth of recent minima was detected. CH Cyg: This starwas in a quiescent phase at a rather bright state. A shallow minimumoccurred at JD 2 452 730, close to the position of the inferiorconjunction of the giant in the inner binary of the triple-star model ofCH Cyg. CI Cyg: Our observations cover the descending branch of a broadminimum. TX CVn: At/around the beginning of 2003 the star entered abright stage containing a minimum at JD 2 452 660. AG Dra: Newobservations revealed two eruptions, which peaked in October 2002 and2003 at 9.3 in U. AR Pav: Our new visual estimates showed atransient disappearance of a wave-like modulation in the star'sbrightness between the minima at epochs E = 66 and E = 68 and itsreappearance. AG Peg: Our measurements from the end of 2001 showedrather complex profile of the LC. RW Hya: Observations follow behaviourof the wave-like variability of quiet symbiotics. AX Per: In May 2003 a0.5 mag flare was detected following a rapid decrease of the light to aminimum. QW Sge: CCD observations in B, V, RC, ICbands cover a period from 1994.5 to 2003.5. An increase in the star'sbrightness by about 1 mag was observed in all passbands in 1997. Lesspronounced brightening was detected in 1999/2000. V934 Her: Ourobservations did not show any larger variation in the optical as areaction to its X-ray activity.
| 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).
| 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 X-Ray Emission of A-Type Stars
From X-ray images in the ROSAT public archives, we determine soft X-rayfluxes, or flux upper limits, for 74 A-type stars, which have beenobserved during deep integrations with the PSPC. Nine supposedly single,late A stars (0.20 < B-V < 0.35) are found to coincide with X-raysources. The X-ray luminosities we infer for these stars range fromlevels comparable to the Active Sun, at log L_x ~27.6, to much brighteremission levels similar to those observed for active late-type binarysystems, near log L_x ~30.1. Another 10 sources are identified withearly A stars (0.0 < B-V < 0.2). Five of these are confirmeddouble stars, the rest are ostensibly single. The maximum luminosity wedetect in the early A stars, log L_x = 30.1, is 3.5 orders of magnitudebrighter than the X-ray upper limits for the nondetected stars.Additional study, including radial velocity monitoring and/or opticalinterferometry, will be needed to determine whether the putativelysingle X-ray emitting stars are in fact single, or whether theiremission is produced entirely or in part by unknown or unresolved binarycompanions. The level of X-ray emission associated with chemicallynormal, single A stars thus far appears to be uncorrelated with anyobvious stellar property, including the rotation rate, which is known togreatly influence the dynamo activity and the X-ray emission levels oflower mass stars. (SECTION: Stars)
| 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.
| Flamsteed stars not contained in the Yale "Catalogue of Bright Stars"
Not Available
| Third preliminary catalogue of stars observed with the photoelectric astrolabe of the Beijing Astronomical Observatory.
Not Available
| Spectral types of 80 early-type stars of variable radial velocity
MK spectral types are given for 80 normal early-type stars of variableradial velocity. These spectral types were determined from spectrogramstaken with the Lick Observatory 0.9-m refractor during the years1957-58.
| UBV photometry of stars whose positions are accurately known. IV
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987A&AS...68..211O&db_key=AST
| HD 154973, a New Short Period Variable Star
Not Available
| Über die Veränderlichkeit der Sterne des Spektraltyps A
Not Available
|
Enviar un nuevo artículo
Enlaces relacionados
- - No se han encontrado enlaces -
En viar un nuevo enlace
Miembro de los siguientes grupos:
|
Datos observacionales y astrométricos
| Constelación: | Hércules |
| Ascensión Recta: | 17h08m33.55s |
| Declinación: | +24°29'11.3" |
| Magnitud Aparente: | 6.842 |
| Distancia: | 112.36 parsecs |
| Movimiento Propio en Ascensión Recta: | 9.8 |
| Movimiento Propio en Declinación: | -49.3 |
| B-T magnitude: | 6.987 |
| V-T magnitude: | 6.854 |
Catálogos y designaciones:
|
