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BVR photometry of a newly identified RS CVn binary star HD 61396
BVR photometry of a recently identified RS CVn binary star HD 61396,carried out during 2001, is presented. The new photometry revealsignificant evolution in the shape and amplitude of light curve whencompared with those reported earlier by Parihar et al. [MNRAS 314 (2000)733]. The traditional two-starspot model has been used to obtain thespot parameters from the observed light curve. Changes in the spot areaand their location on the stellar surface are discernible from theextracted parameters from the new photometry.
| Optical, X-ray and radio observations of HD 61396: a probable new RS CVn-type binary
We have carried out BVR photometric and Hα spectroscopicobservations of the star HD 61396 during 1998 March 20 to 1999 April 3.We have discovered regular optical photometric variability from thisstar, with an inferred period of 31.95+/-0.10d, and an amplitude of~0.18mag. A possible period of 35.34+/-0.12d, as determined withHipparcos, cannot be completely ruled out, however. Modelling of itsphotometric light curve with two circular spots indicates that 5-21 percent of the stellar surface is covered by dark starspots which are ~830Kcooler than the surrounding photosphere, and produce the observedrotational modulation of the optical flux. Optical spectroscopy revealsa variable Hα emission feature, indicating that it is an unusuallyactive star. In addition, we have analysed archival X-ray data of HD61396, obtained from serendipitous observations with the ROSAT X-rayobservatory, and we also discuss the radio properties of this star,based on both published Green Bank and unpublished VLA observations. Thestrong photometric variability and Hα emission, the relativelyhard X-ray spectrum, and the high X-ray and radio luminosities implythat HD 61396 is most likely to be a member of the RS CVn class ofevolved active binary stars. Its X-ray and radio luminosities place itamong the five most luminous active binaries detected so far.
| 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.
| Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
| SAO stars with infrared excess in the IRAS Point Source Catalog
We have undertaken a search for SAO stars with infrared excess in theIRAS Point Source Catalog. In contrast to previous searches, the entireIRAS (12)-(25)-(60) color-color diagram was used. This selection yieldeda sample of 462 stars, of which a significant number are stars withcircumstellar material. The stars selected can be identified aspre-main-sequence stars, Be stars, protoplanetary systems, post-AGBstars, etc. A number of objects are (visual) binary stars.Characteristic temperatures and IR excesses are calculated and theirrelations to spectral type are investigated.
| Hyades and Sirius supercluster members brighter than magnitude (V) 7.1. II - Right ascension six to twelve hours
The present star sample is contained in the Bright Star Catalogue andits Supplement, augmented with a further supplement of 788 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 788 starsdiscussed here, as well as all supercluster members.
| UBV photometry of FK4 and FK4 supplement stars
Traditional UBV filters, together with a photomultiplier, have been usedin 40-m Cassegrain telescope observations of all northern stars of theFK4 catalog and its supplement, which have heretofore lacked V and V-Bmeasurements. The resulting UBV photometry for 320 stars is presented intabular form.
| Photometrie de la comete Arend-Roland.
Not Available
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| קבוצת-כוכבים: | ג'ירף |
| התרוממות ימנית: | 07h32m02.22s |
| סירוב: | +61°45'28.0" |
| גודל גלוי: | 6.7 |
| מרחק: | 150.376 פארסק |
| תנועה נכונה: | -16 |
| תנועה נכונה: | -119.5 |
| B-T magnitude: | 7.926 |
| V-T magnitude: | 6.802 |
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