Contents
Images
Upload your image
DSS Images Other Images
Related articles
Spectroscopy and Photometry of the Double-lined Binary HD 149420
We have used new spectroscopic and photometric observations of HD 149420to obtain an improved orbital element solution and determine some basicproperties of the system. This double-lined binary has an orbital periodof 3.39430 days, a circular orbit, and a mass ratio of 0.52. The primaryis somewhat evolved, with an A9 IV spectral type, while the secondary isestimated to be an F5: dwarf. The secondary may be synchronouslyrotating, but the primary is rotating substantially slower than itssynchronous velocity. Our photometric observations confirm the lightvariability and period found by Hipparcos. We determine a photometricperiod of 1.698 days, essentially half the value of the orbital period,with a peak-to-peak amplitude of 0.028 mag in V. In addition to thisellipsoidal light variation, we also detect more rapid, low-amplitudevariability with a period of 0.076082 days and a peak-to-peak Vamplitude of 0.008 mag, as well as a possible second short 0.059256 dayperiod with a peak-to-peak amplitude of only 0.005 mag. This indicatesthat the A9 IV primary in HD 149420 is a pulsating δ Scutivariable. Our binary model that best fits both the radial velocity andphotometric observations indicates the possibility of extremely shallowgrazing eclipses, a circumstance not unexpected given the large minimummasses from the orbital solution, the evolved nature of the primary, andthe short orbital period.
| The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core
Doppler measurements from Subaru and Keck have revealed radial velocityvariations in the V=8.15, G0 IV star HD 149026 consistent with aSaturn-mass planet in a 2.8766 day orbit. Photometric observations atFairborn Observatory have detected three complete transit events withdepths of 0.003 mag at the predicted times of conjunction. HD 149026 isnow the second-brightest star with a transiting extrasolar planet. Themass of the star, based on interpolation of stellar evolutionary models,is 1.3+/-0.1 Msolar together with the Doppler amplitudeK1=43.3 m s-1, we derive a planet massMsini=0.36MJ and orbital radius 0.042 AU. HD 149026 ischromospherically inactive and metal-rich with spectroscopically derived[Fe/H]=+0.36, Teff=6147 K, logg=4.26, and vsini=6.0 kms-1. Based on Teff and the stellar luminosity of2.72 Lsolar, we derive a stellar radius of 1.45Rsolar. Modeling of the three photometric transits providesan orbital inclination of 85.3d+/-1.0d and (including the uncertainty inthe stellar radius) a planet radius of (0.725+/-0.05)RJ.Models for this planet mass and radius suggest the presence of a ~67M⊕ core composed of elements heavier than hydrogen andhelium. This substantial planet core would be difficult to construct bygravitational instability.Based on data collected at the Subaru Telescope, which is operated bythe National Astronomical Observatory of Japan.Based on observations obtained at the W. M. Keck Observatory, which isoperated by the University of California and the California Institute ofTechnology. Keck time has been granted by NOAO and NASA.
| 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
| RX J1643.7+3402: A new bright cataclysmic variable
We report the discovery of a new bright (V ~ 12.6) cataclysmic variablestar identified with the ROSAT X-ray source RX J1643.7+3402.Spectroscopic and photometric observations show it to be a novalikevariable sharing some of the characteristics of the SW Sex sub-class ofnovalike CVs. The spectroscopic period may be either 2\fh575 or 2\fh885,within the period ``gap''. A photometric modulation with a probableperiod of 2\fh595 and an amplitude of ~ 0.1 mag in V is present on mostnights and could be either a ``positive" or a ``negative" superhumpmodulation (depending on the exact spectroscopic period), indicating thepresence of a precessing accretion disk in this system. Rapid variationsof 0.1 to 0.2 mag amplitude in V repeat with a time scale of ~ 15 min.Partly based on observations obtained with the Byurakan Observatory2.6-m telescope and with the OHP 1.93-m and 1.2-m telescopes.
| 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).
| The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants
We present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| Lightcurve and Period of the System V450 Herculis
Not Available
| V 450 Herculis.
Not Available
| 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.
| Third preliminary catalogue of stars observed with the photoelectric astrolabe of the Beijing Astronomical Observatory.
Not Available
| ICCD speckle observations of binary stars. I - A survey for duplicity among the bright stars
A survey of a sample of 672 stars from the Yale Bright Star Catalog(Hoffleit, 1982) has been carried out using speckle interferometry onthe 3.6-cm Canada-France-Hawaii Telescope in order to establish thebinary star frequency within the sample. This effort was motivated bythe need for a more observationally determined basis for predicting thefrequency of failure of the Hubble Space Telescope (HST) fine-guidancesensors to achieve guide-star lock due to duplicity. This survey of 426dwarfs and 246 evolved stars yielded measurements of 52 newly discoveredbinaries and 60 previously known binary systems. It is shown that thefrequency of close visual binaries in the separation range 0.04-0.25arcsec is 11 percent, or nearly 3.5 times that previously known.
| New Delta-a-photometry of peculiar A-type stars - Evidence for a two-component-structure of the lambda 5200-feature
The paper presents photoelectric photometry of Ap and normal A-typestars in a filter system which resembles the system introduced byMaitzen (1976) in order to measure the strength of the 5200-A feature.It is found that the 5200-A depression cannot be due to a single opacitysource but is composed of two main components with different temperaturebehavior: a broad, shallow feature and a narrow, rather deep one. Thelatter is centered on about 5175 A and shows its greatest strength atthe hottest Ap stars; the former peaks at somewhat longer wavelengthsand at a lower temperature.
| MK spectral types for some F and G stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979PASP...91...83C&db_key=AST
| Photoelectric K-line indices for 165 B, A and F stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...34..441P&db_key=AST
| Absolute luminosity calibration of F stars
Luminosity calibrations are performed for a restricted sample of 706F-type field stars of all luminosity classes and a similarly restrictedsample of 251 main-sequence F stars. The samples are restricted withrespect to values of photometric and metallicity indices, propermotions, radial velocities, and apparent magnitudes. Both linear andsecond-order relations between absolute magnitude and the photometricindices beta, /c1/ or (b-y), /c1/ are considered.These relations are calibrated by the statistical parallax method basedon the principle of maximum likelihood. The possible effect ofinterstellar absorption on the calibration results is investigated alongwith an effect of a photometric correction to the absolute magnitudes.The results obtained are compared with those of Crawford (1975) as wellas with the trigonometric parallaxes. The coefficients of thecalibration relations are derived from the trigonometric parallaxes, andpoor agreement is indicated. It is concluded that the trigonometricparallaxes must be used very carefully and only for nearby stars.
| Spectral classification of the bright F stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88...95C&db_key=AST
| Positions moyennes et mouvements propres de 355 etoiles DU GC de la zone de declinaison +33 +36.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...26..219M&db_key=AST
| MK classifications for F-and G-type stars. 3.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..682H&db_key=AST
| Space distribution and kinematics of local early F stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75...35R&db_key=AST
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Hercules |
| Right ascension: | 16h43m51.70s |
| Declination: | +34°02'20.0" |
| Apparent magnitude: | 5.99 |
| Distance: | 54.975 parsecs |
| Proper motion RA: | -73.3 |
| Proper motion Dec: | 57.6 |
| B-T magnitude: | 6.39 |
| V-T magnitude: | 6.049 |
Catalogs and designations:
|
